Pathoma-Lecture-Notes

4.2 Secondary Hemostasis

1. What does secondary hemostasis do?
• It creates fibrin mesh via coagulation cascade to stabilize platelet plug.
• It creates thrombin (factor IIa). Thrombin converts fibrinogen to fibrin (factor Ia). Fibrin is then
cross linked.

2. What causes disorders of secondary hemostasis?
• They occur due to factor abnormalities.

3. What is clinical presentation of disorders of secondary hemostasis?
• Deep bleeding in muscles and joints (recall that disorders of primary hemostasis has bleeding in
skin and mucosal surface)
• Rebleeding after surgical procedures

4. How do extrinsic and intrinsic pathway of coagulation cascade start? What lab tests measures intrinsic
and extrinsic pathways? What lab test is better is coumadin vs heparin?

• Intrinsic pathway - Starts with factor 12 which is activated by subendothelial collagen (SEC).
Measured by PTT lab test. Heparin results is better measured by PTT (PTT measures Hep - 3 letters
each)

• Extrinsic pathway - starts with factor 7 which is activated by tissue thromboplastin. Measured by
PT lab test. PT measures coumadin results.

Hemophilia A
9. What causes hemophilia A (think hemophilia 8)? What is it's clinical presentation?

• Caused by genetic factor 8 deficiency
• x- linked recessive.
• Can arise from new mutation without any family history
• Deep tissue, joint and post-surgical bleeding.

10. What are lab findings in hemophilia A?
• Elevated PTT, normal PT (factor 8 is a part of intrinsic pathway and PTT measures intrinsic
pathway)
• Low factor 8
• Normal platelet count and bleeding time

11. How do you treat hemophilia A?
• Give recombinant factor 8.

Hemophilia B
12. What causes hemophilia B (aka christmas disease)? What are its clinical features? What are the lab
values?

• Caused by genetic deficiency in factor 9.
• Clinically resembles hemophilia A.
• Lab values - same as hemophilia A except low factor 9 instead of factor 8.

Coagulation factor inhibitor disease
13. What is coagulation factor inhibitor disease? What factor is most commonly inhibited?

• Patient acquires antibody against coagulation factor which impairs factor function. Anti-factor 8
antibody most common.

• Clinical presentation same as hemophilia A.

Hemostasis Page 3.1

• Clinical presentation same as hemophilia A.

14. How do you distinguish hemophilia A from coagulation factor inhibitor disease in lab? (HY)
• You mix patient's plasma with normal plasma (i.e, pt gets some normal factor 8).
• If you measure PTT time after that, hemophilia A pt will have lower PTT time whereas coagulation
factor inhibitor disease patient will have same PTT time (as the antibodies will destroy new factor
8).

Von Willebrand disease
15. What is Von Willebrand disease? What is the most common type of vWF disease?

• Most common inherited coagulation disorder. (HY)
• Genetic deficiency in vWF factor (vWF required for stabilization of factor 8). Defect can be

qualitative or quantitative.
• Most common type is autosomal dominant with decreased vWF levels.

16. What are clinical presentation of vWF disease?
• Mild mucosal and skin bleeding. Even though their PTT is elevated, they don't get secondary
hemostasis disease symptoms.

17. What are lab values?
• Increased bleeding time
• Increased PTT time, normal PT
• Abnormal ristocetin test (HY)

18. Why is PTT elevated in vWF disease even though it's a platelet disease? (HY)
• PTT is elevated because vWF is required to stabilize factor 8. Bad factor8 leads to elevated PTT.

19. What is ristocetin test?
• The antibiotic ristocetin causes von Willebrand factor to bind the platelet receptor glycoprotein Ib
(GpIb), so when ristocetin is added to normal blood, it causes agglutination.

Ristocetin drug + pt blood

vWF disease - No agglutination

Bernard-Soulier (Gly Ib deficiency) - No agglutination

Glanzmann thrombasthenia - Yes agglutination
(Gly IIb/IIIa deficiency)

20. What is treatment for vWF disease? What's the mechanism? (HY)
• Desmopressin - they increase vWF release from Weibel Palade bodies of endothelial cells (primary
site of VWF storage, another substance in Weibel palade bodies = P selectin).

21. What is the function of vit K in coagulation cascade? How does coumadin work?(HY)
• They are necessary for gamma carboxylation of factor 2,7,9,10, factor c, factor s
• Vit K is activated by epoxide reductase in liver (coumadin blocks epoxide reductase and prevents
activation of vit K)

22. What causes vitamin K deficiency?
• Vit K is generated by bacteria in our gut. So deficient pt either take less vit K or have abnormal
bacteria.
○ Newborns (their gut is not well inhabited by bacteria) - newborns are prophylactically given
vit K.
○ Long term antibiotic therapy

Hemostasis Page 3.2

○ Long term antibiotic therapy
○ Malabsorption (if fat absorption is impaired)
23. Why does liver failure lead coagulation disease?
• Liver makes coagulation factors
• Epoxide reductase that activates vitamin K is found in liver
24. How to you observe liver failure patients for their coagulation function?
• By measuring their PT time (why?)
25. What does large volume transfusion lead to secondary coagulation problems?
• Because it dilutes the coagulation factors.

Hemostasis Page 3.3

4.3 Other Disorders of Hemostasis

Heparin induced thrombocytopenia
1. How does heparin induced thrombocytopenia occur? What is a complication of this?
- Heparin can bind to platelet factor 4. IgG antibodies can bind to them creating a complex. This
complex activates platelets and makes little clots in blood vessels. Resulting effect is low platelet
in blood.
- Thrombosis - Fragment of destroyed platelets can attract remaining platelet leading to
thrombosis.

2. What drug is risky to give to patients with heparin induced thrombocytopenia?
- Give other thrombolytic drug but not warfarin (coumadin). It is because cumadin can cause tissue

necrosis. MOA - coumadin also inhibits protein C in addition to inhibiting factor 2,7,9 and 10.
Protein C is an anti-clot forming factor and has shorter half-life. Therefore, coumadin acts as
procoagulant initially which leads to microthrombi in penis, skin etc and lead to necrosos.

Disseminated intravascular coagulation
3. What is disseminated intravascular coagulation disorder (DIC)? What is its clinical presentation?
- It's pathologic activation of coagulation cascade.
- Clinical presentation -
○ ischemia and infraction due to widespread microthrombi.
○ Bleeding seen from IV sites and mucosal surface (hematuria, bleeding from gut, mouth)due
to thrombocytopenia (thrombin is one major activator of platelets and can lead to
thrombocytopenia).

4. What are some causes of disseminated intravascular coagulation disorder (DIC)?
- This disease is always secondary to another disease

○ Obstetric complication - amniotic fluid contains tissue thromboplastin that can activate
factor 7 and hence the coagulation cascade.

○ Sepsis - bacterial toxins can activate coagulation cascade. Also, macrophage can produce IL1
and TNF that can activate coagulation cascade indirectly.

○ Adenocarcinoma - mucin from adenocarcinoma can activate coagulation cascade
○ Acute promyelocytic leukemia - Cells are loaded with primary granules that can coalesce to

make hour rods (classic histologic feature). Primary granules can enter circulation and
activate coagulation cascade.
○ Rattlesnake bite (HY) - venom can activate coagulation cascade

5. What are lab findings in disseminated intravascular coagulation disorder? What is the best lab
test?

- Low platelet count
- Increase PT and increase PTT
- Decrease fibrinogen
- Microangiopathic hemolytic anemia
- Elevated D-dimer (HY) - Best lab test - D dimer is product of breaking cross linked fibrin. If lots of

clots are forming, some are dissolving as well, increasing D-dimer in blood.

6. What is treatment for disseminated intravascular coagulation disorder?
- Treat underlying cause
- Transfuse blood products and cryoprecipitate, as needed

Hyperactive plasmin

Hemostasis Page 4.1

Hyperactive plasmin
7. How is plasmin formed? What are its functions? How is it inactivated?
- Normally, plasminogen is converted to plasmin by tPA (tissue plasminogen activator).
- Plasmin's function -
○ dissolves the cross-linked fibrin,
○ cleaves and destroys fibrinogen
○ destroys coagulation factors,
○ blocks platelet aggregation.
- Plasmin is inactivated by alpha-2-antiplasmin
8. What happens if plasmin is hyperactive? What are some conditions that give rise to hyperactive
plasmin?
- It prevents clot formation due to destruction of coagulation factors and fibrinogen
- Radical prostatectomy - releases urokinase that activates plasmin
- Cirrhosis of liver - it causes reduction if production of alpha 2 antiplasmin
9. What is clinical presentation of hyperactive plasmin?
- Presentation is same as DIC

10. What are lab findings in hyperactive plasmin? Contrast it with DIC lab findings.
- Increased PT and PTT
- Increased bleeding time with normal platelet count (DIC has low platelet count)
- Increased fibrinogen split products without D-dimers (low D-dimer as there's no fibrin to cleave)

11. How do you treat hyperactive plasmin conditions?
- Give aminocaproic acid. It blocks activation of plasminogen.

Hemostasis Page 4.2

4.4 Thrombosis

1. What is thrombosis? What is most common site?
- Pathologic intravascular clot that can form in any artery or vein is called thrombosis.
- Most common site is deep vein (DVT) below the knee.

2. What characterizes a thrombus from postmortem clot?
- Line of zahn
- Attachment to vessel wall

Fig - lines of Zahn (the alternate layer of RBC and fibrosis - marked by R & f) is characteristic
of thrombosis

3. What are 3 main risk factor of thrombosis (virchow's triad)? Give examples of each.
- Disruption of blood flow - stasis or turbulence of flow. Ex - immobilization, cardiac wall

dysfunction, MI, aneurism (there's turbulence in an aneurism)
- Endothelial damage. Ex - artherosclerosis, vasculitis, high level of homocysteine (vit B12 or folate

deficiency or homocystinurea)
- Hypercoagulable state (excess procoagulant or defective anticoagulant)

4. How does intact endothelium prevents thrombosis?
- It blocks exposure of tissue collagen and tissue factors from coagulation factors and platelets
- It makes prostaglandin I2 (prostacyclin) that blocks platelet aggregation. It's function is opposite of

thromboxane A2 made by platelets.
- It secretes heparin like molecules (HLM). HLM activate antithrombin 3.
- It's makes t-PA that activates plasmin.
- It makes thrombomodulin. Thrombomodulin enhances activation of protein C by thrombin.

Protein C is inhibitor of coagulation factors - 5 and 8.

5. Why does vit B12 or folate deficiency causes high level of homocysteine?
- Because vit B12 and folate are needed to convert homocysteine to methionine.
- MOA - Folate becomes tetrahydroflorate in body. It gets activated by giving its methyl group to vit

B12. It then participates in DNA synthesis. Vit B12 gives the methyl group to homocysteine and
homocysteine becomes methionine.
- High level of homocysteine is damaging to the endothelium

Homocystinurea
6. What is homocystinurea (aka cystathione beta synthase (CBS) deficiency)?
- Disease with high level of homocystine caused due to deficiency in Cystathione beta synthase
enzyme. CBS converts homocystine to cystathionine.

Hemostasis Page 5.1

enzyme. CBS converts homocystine to cystathionine.

7. What is clinical presentation of homocystinurea?
- Vessel thrombosis (1/4th of pt die in young age due to thrombosis)
- Mental retardation
- Long slender fingers
- Lens dislocation

8. What is classic presentation of thrombosis for pt with hypercoagulable state?
- Pt has recurrent DVT or DVT at young age
- Common sites are DVT, hepatic and cerebral veins.

Protein C and S deficiency
9. Describe protein C or S deficiency?
- It's a hypercoagulable state. Protein C with cofactor protein S are anticoagulants because they
inactivate factor 5 and 8.
- Pt are at increased risk for warfarin necrosis

10. What is MOA for warfarin necrosis?
- Warfarin blocks production of factors 2,7,9, 10, protein C and protein S by inactivating vit K
epoxide synthase (VKOR).
- VKOR's function is to recycle inactive vit K epoxide to active vit K. Vit K is needed to synthesize
factors 2,7,9,10, protein C and protein S.
- Protein C is anticoagulant which inactivates factor 5 and 8. It has the shortest half-life so it's the
first one to go away when warfarin is used.
- Therefore, when warfarin is use, it's first action is procoagulant due to loss of protein C. It can
make thrombus and cause necrosis.

11. Describe factor V leiden condition.
- Most common inherited hypercoagulable state.
- Patient has mutated factor V that lacks cleavage site for deactivation by protein C and S.

12. What is prothrombin 20210A condition?
- Hypercoagulable state due to inherited point mutation in prothrombin that causes increased gene
expression.

13. What is antithrombin 3 deficiency? What happens if you give them heparin? How are these
patients managed for their hypercoagulable state?

- It's a hypercoagulable state.
- Their PTT won't rise if you give normal dose heparin because heaparin works by increasing

antithrombin 3. PTT will rise a little with high doses.
- Start pt in high dose of heparin and then give warfarin.

14. Why are oral contraceptives associated with hypercoagulable state?
- It is because estrogen increases the production of coagulation factors and oral contraceptives
usually work by increasing estrogen levels.

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usually work by increasing estrogen levels.

Hemostasis Page 5.3

4.5 Embolism

1. What is embolism?
- It's a intravascular mass that travels and occludes downstream vessels.
- Thromboembolism is most common type (>95%) - embolus will have line of Zahn?.
2. What is atherosclerotic embolus?
- It's an atherosclerotic plaque that dislodges. It's characterized by presence of cholesterol

clefts in embolus.

Fig - presence of cholesterol crystal (three white columns) indicates that this embolus is
artherosclerotic and not thrombotic.
3. When does fat embolus occur? What is its clinical presentation?
- Associated with bone fractures - while the fracture is present or shortly after repair
- The embolus mostly travels to lung so classic signs are dyspnea and petechiae on skin
overlying the chest

Fig - fat embolus
4. What causes gas embolus? What is classic presentation?
- When a diver goes deep down in water, high pressure causes nitrogen to dissolve in blood.

When they come back up, the nitrogen makes bubbles causing embolus.
- It can also be caused by air pumped in laproscopic surgery
- Presents with 'bends and choke' - respiratory problem and joint, muscle pain due to embolus

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- Presents with 'bends and choke' - respiratory problem and joint, muscle pain due to embolus
in lungs, muscle and joint.

5. What is Caisson disease (aka diver's disease)?
- Chronic form of gas embolus disease. Presents with multifocal ischemic necrosis of bone.

6. What is amniotic fluid embolus?
- Amniotic fluid enters maternal circulation usually during labor and cause embolus.
- Classic presentation is SOB, neurologic symptoms due to embolus in lung and brain. Pt also

might get DIC (disseminated intravascular coagulation disease- pathologic activation of
coagulation cascade).

7. Why do patient with amniotic fluid embolus at high risk for DIC?
- Because amniotic fluid is filled with tissue thromboplastin which activates factor 7 that leads

to activation of extrinsic coagulation cascade.

8. What is characteristic finding in amniotic fluid embolus?
- Embolus will have squamous cell and keratin debris from baby's skin.

Fig - amniotic fluid embolus in a blood vessel near alveoli. Note presence of keratin debris
(squiggly lines) inside the blood vessel.

9. What is most common cause of pulmonary embolism (PE). What is its most common clinical
presentation?

- Most common due to thromembolus from DVT.
- Most PE are clinically silent as lung has dual supply from pulmonary artery and bronchial

artery. Also, the embolus are usually small and self-resolve.

9. What increases chance of pulmonary infraction from PE? What is the gross feature of
infraction?

- Obstruction of large or medium sized artery
- Pre-existing cardiopulmonary compromise
- Hemorrhagic wedge shaped infraction (hemorrhagic because tissue in lung is loosely

organized and reperfusion occurs from the dual arterial supply).

10. What is clinical features of PE in symptomatic cases?
- SOB, hemoptysis, pleuritic chest pain, and pleural effusion
- VQ mismatch with abnormal perfusion
- Spiral CT shows vascular filling defect in lung
- IMP - pt mostly have DVT and elevated D-dimer

11. What causes immediate death in PE?

Hemostasis Page 6.2

11. What causes immediate death in PE?
- Saddle embolus (embolus that blocks at branching of pulmonary artery - both pulmonary
artery blocked) leads to electromechanical disturbance in heart (too much blood backing up)
causes immediate death.

12. Explain how PE can lead to pulmonary HTN.
- When chronic emboli are reorganized over time, it leads to pulmonary HTN.

13. What is the most common source of systemic embolus? Where do they most commonly
dislodge?

- Most commonly arise from left heart. Most commonly dislodge in lower extremities.

Hemostasis Page 6.3

Chapter 5: Red Blood Cell Disorders

CMAP summary

RBC disorders Page 1.1

5.1 Anemia

1. What is anemia? What’s its presentation?
- Reduction in total circulating RBC mass
- Presentation (hypoxia):

o Pale conjunctiva and skin
o Weakness, fatigue, dyspnea
o Headache and lightheadedness
o Angina, especially with CAD
2. How is anemia measured?
- Hb, Hct and RBC count (total RBC mass difficult to measure)
- All of these measures are concentration dependent so have problems. Ex – in pregnancy, blood volume
increases making Hb and Hct concentration low even though total amount might be same. Immediately
after gunshot wound and blood loss, Hb and Hct concentration might be normal even though pt might
have lost lots of blood.
3. What is practical definition of anemia?
- Hb<13.5 g/dl for males and Hb<12.5 g/dl for females. (lower for females because of menstruation)
4. What are different types of anemia?
- Microcytic (MCV – mean corpuscle volume <80) – small RBC
- Normocytic (MCV = 80-100) – normal size RBC
- Macrocytic (MCV > 100) – big RBC

RBC disorders Page 2.1

5.2 Microcytic Anemia (Part 1) - Fe Deficiency

Tuesday, October 27, 2015 9:23 PM

1. What is pathophysiology of microcytic anemia?
- Main problem in microcytic anemia is decreased production of Hb.
- RBC is produced from subsequent division of erythroblast (EB). During Hb deficiency, EB divides too

much. As a result, RBCs become small and microcytic anemia occurs. If erythroblast doesn’t divide
enough, macrocytic anemia occurs.
- Think that by dividing extra, RBC surface area exposed to blood increases and it can carry more O2 – not
correct idea but works for thinking

Fig: microcytic anemia. Normal RBC size is equal to size of nucleus of lymphocyte. Notice that multiple
RBC are smaller than that. Also notice variability in size of RBC and increased pallor in center of RBC
2. What is hemoglobin made up of?
- Hemoglobin = heme + globin (protein).
- Heme = Iron + protoprophyrin.
3. What are etiologies of microcytic anemia (Hb deficiency)?
- Fe deficiency
- Anemia of chronic state- being unable to use Fe. In chronic inflammation, Fe is stored away in
macrophage and can’t be used.
- Cideroblastic anemia – protoprophyrin deficiency
- Thalessemia – decreased production of globin

RBC disorders Page 3.1

Fe deficiency anemia

4. What is epidemiology Fe deficiency anemia.
- Fe deficiency is the most common nutritional deficiency in the world making this the most common type

of anemia (1/3rd of world is deficient in Fe)

5. Describe digestion and storage of Fe (HY).
- Fe is absorbed in duodenum (HY). Protein called FERROPORTEIN plays a key role in Fe transport from

lumen to enterocyte to blood.
- TRANSFERRIN transports iron in blood and takes it to liver and bone marrow macrophage for storage
- Stored intracellular iron is bound to FERRITIN
- There is no real way to get rid of Iron from body. So absorption by enterocytes is regulated. (some lost

during skin sloughing off and menstruation)
- Iron is always bound to something because free Fe generates free radical by fenten reaction.

6. What are lab measurement for Fe in body?
- Serum Fe – measures Fe in blood (most of it is bound to transferretin)
- TIBC (total iron binding capacity) – tells total transferritin in blood. Normally, 1 in every 3 transferritin in

blood is bound to Fe.
- % saturation – % saturation of transferritin by Fe
- Serum ferritin – indication of how much Fe is in storage sites
- When ferritin↓, TIBC ↑ and vice versa(liver makes more TIBC to search for more Fe)

7. What are some etiologies of Fe deficiency anemia?
- Malabsorption –

o Celiac
o Gastrectomy (HY)– Fe 2+ is absorbed easily (Fe 2 goes INTO the body). Acidic environment

promotes Fe 2 conformation. When stomach is resected, due to lost acidity, more Fe will be in 3+
and Fe won’t be absorbed well.

RBC disorders Page 3.2

and Fe won’t be absorbed well.
- Other etiologies are based on blood loss of dietary lack

• Infants – breast feeding (breast milk has no Fe)
• Children – poor diet
• Adults –

▪ peptic ulcer disease (most common cause in adult males);
▪ Menorrhagia (too much bleeding during periods) or pregnancy (females).
• Elderly –
▪ colon polyps/carcinoma (western world);
▪ hookworm (developing world)
8. What are stages of iron deficiency anemia?
- Depletion of iron storage (low serum ferretin)
- Depletion of serum iron
- Normocytic anemia (HY) – first there will be few but normal sized RBC
- Microcytic, hypochromic anemia (central pallor in RBC is big)
- Know that Normocytic anemia is followed by microcytic in Fe deficiency anemia
9. What are clinical presentation of iron deficiency anemia?
- Anemia
- Koilonychia (spoon shaped nails)
- Pica (psychological drive to eat dirt – perhaps to get Fe)

10. What are lab findings of Fe deficiency anemia?
- Microcytic, hypochromic anemia with ↑RDW (RDW is like standard deviation of size of RBC; larger the
variation in RBC sizes, larger the RDW) – due to transition from normocytic to microcytic anemia
- ↓ferritin, ↑TIBC
- ↓serum iron, ↓%saturation
- ↑FEP (free erythrocyte protoporphyrin)

11. Why is there ↑FEP in Fe deficiency anemia?
- As Fe is low but protoporphyrin is normal, some protoporphyrin will be unbound to Fe hence increasing
the FEP.

12. What is blood smear finding in Fe deficiency anemia?

RBC disorders Page 3.3

- Poikilocytosis (variable shapes), anisocytosis (variable size), cigeratte shaped RBC (classic finding), tear
drop RBC

- Microcytic anemia (note RBC smaller than lymphocyte nucleus)
13. What is treatment of Fe deficiency anemia?

- Iron supplement – Ferrous sulfate
- Rule out any risk factors (ex – if old people, rule out colon carcinoma)
14. What is Plummer-Vinson syndrome?
- Iron deficiency anemia with esophageal web and atrophic glossitis (smooth tongue due to lack of white

papillae- beefy red appearance)

RBC disorders Page 3.4

5.2 Microcytic Anemia (Part 2) - Anemia of Chronic Disease

Anemia of chronic disease

1. What is epidemiology of anemia of chronic disease (ACD)?
- Most common anemia in hospitalized pt.

2. What is pathophysiology of ACD?

- During acute/chronic inflammation, acute phase proteins are produced. One of them is Hepcidin. It has

2 functions that results in anemia
o ↓Erythropoietin production
o Increased sequestering of Fe in macrophage. Less transfer of Fe to erythroid precursors will result

in Fe deficiency, which results in anemia.

- Evolutionary advantage of hepcidin is that bacteria need Fe to grow and flourish.

3. What are lab findings in ACD?
- ↑ferritin, ↓TIBC
- ↓serum iron (bone marrow takes Fe from serum as macrophage isn’t giving it), ↓% saturation
- ↑FEP (free erythrocyte protoporphyrin) (due to low available Fe but normal protoporphyrin, free

protoporphyrin will ↑)

4. What are stages of ACD?
- Normocytic anemia is followed by microcytic anemia (same as Fe deficiency anemia)

5. What is treatment of ACD?
- Treat underlying cause of chronic disease (to reduce hepcidin)
- Exogenous erythropoietin (especially helpful in cancer pt)

6. What are lab difference between Fe deficiency anemia and ACD?

Fe deficiency Anemia of chronic Hemochromato Oral contraceptive pill
anemia disease sis (OCP)

Serum Fe ↓ ↓ ↑

Transferrin/TIB ↑ ↓ ↓↑
C

Ferretin ↓ ↑ ↑

- Transferrin/TIBC change is always opposite of ferretin. Look at ferretin first.
- TIBC (total iron binding capacity) is a measure of Transferrin

Sideroblastic anemia (sidero = related to iron)

7. What is pathophysiology of sideroblastic anemia?
- Low synthesis of protoporphyrin is main cause.
- If protoporphyrin is deficient, Fe is trapped in mitochondria. As mitochondria surround nucleus, Fe

trapping presents as ringed sideroblasts.

RBC disorders Page 4.1

Fig: ringed sideroblasts seen in bone marrow biopsy (purssian blue stain – marks Fe)
8. What are steps of heme synthesis?

- First and last three reactions take place inside mitochondria

9. What are etiologies of sideorblastic anemia? Acquired

Congenital Alcoholism (EtOH is mitochondrial poison that damages
protoporphyrin production)
Mutation of ALAS (most common cause of
congenital sideroblastic anemia) - XR Lead poisioning (denatures ALAD and ferrocheletase)

RBC disorders Page 4.2

Vit B6 deficiency (ALAS requires Vit B6 as cofactor) –
Isoniazid treatment can cause Vit B6 deficiency

10. What are clinical features of lead poisoning leading to sideroblastic anemia?
- Pt at old house with chipped paint at high risk
- Mnemonic LEAD:
o L - Lead lines on gingivae and metaphyses of long bones (aka Burton lines)
o E - Erythrocyte basophilic stippling and encephalopathy (lead inhibits rRNA degradation causing
RBCs to retain aggregates of rRNA seen as basophilic stippling)
o A - sideroblastic Anemia, Abdominal colic
o D - Dimercaprol and EDTA for treatment; Wrist and foot Drop
o Succimer used for chelation in kids - sucks to be kid that eats lead

Fig: From right to left - basophilic stippling; Burton lines on gum; metaphysis
11. What are lab findings in sideroblastic anemia? What's its treatment?

- Lab findings based on Fe overload as they can’t attach to portoprophyrin
- As Fe increase in erythroblast, cells die due to free radical produced by Fenten reaction. Fe leaks out and

is taken by macrophage.
- ↑ferritin, ↓TIBC
- ↑serum Fe, ↑% saturation
- Very similar lab findings as hemochromatosis
- Treatment:

o Pyrodoxine (B6 - cofactor for ALAS)

RBC disorders Page 4.3

5.2 Microcytic Anemia (Part 3)

Thalassemia

1. What are normal globin molecule in hemoglobin?
Hemoglo a- b- Developmental
bin subunit subunit stage

HbF a Υ Fetal, persists for 6
moths after birth

HbA α β Adult

HbA2 α δ Adult (“Other adult”)

2. How does thalassemia lead to microcytic anemia?
- Thalassemia is decreased synthesis of globin chains. It results in reduced hemoglobin which leads to

microcytic anemia. In sickle cell, there's defect in globin chain.

3. What are patients with thalassemia protected against?
- Malaria by plasmodium falciparum.

4. What causes alpha thalassemia? What chromosome is alpha gene located in?
- Alpha thalassemia is caused due to gene deletion of alpha chain of hemoglobin.
- Normally, 4 alpha alleles are present on chromosome 16 (2 allele per chromosome)
- 'a in alpha looks like d (deletion); if you rotate b in beta, you get m (mutation).

5. What are subtypes of alpha thalassemia?

1 alpha 2 alpha allele deleted 3 alpha allele deleted - 4 alpha allele
allele HbH B chain tetramer deleted - Hb Bart
deleted Hydrops fetalis
- Severe anemia
- Asymptom - Mild anemia with slightly increased RBC - Lethal in utero
(hydrops
atic count (remember in microcytic anemia, fetalis)

patient erythroblast divides more)

- Cys deletion (deletion of both allele on - No problem in fetus

same chromome) is worse than trans (one good alpha allele

deletion (deletion of two allele on different takes care)

chromosome) because cys is associated

with increased risk of severe thalassemia in

offspring

- Cis deletion classically seen in Asians - When HbA and HbA2 are - Gamma chain
(higher rate of spontaneous abortion in
formed, B chain tetramers(aka

RBC disorders Page 5.1

(higher rate of spontaneous abortion in formed, B chain tetramers(aka
Asia is partly due to this) tetramers (aka HbH) are Hb Barts) are
- Trans deletion classically seen in Africans formed (4 B combine formed
due to bad A)

- HbH can be seen on - Hb Barts seen
electrophoresis on
electrophoresis

6. What causes beta thalassemia? What chromosome is beta gene located in?
- Beta thalassemia is caused due to mutation of beta chain of hemoglobin. Mutations result in absent (aka

B0) or diminished (aka B+) production of B-globin chain.
- Normally, 2 beta alleles are present on chromosome 11 (1 allele per chromosome)

7. What are subtypes of beta thalassemia? B0/B0
B/B+
- Aka Beta thalassemia minor - Aka Beta thalassemia major
- Pt usually asymptomatic with increased - Pt has severe anemia few months after birth as α4
RBC count tetramer will form (instead of α2β2)
- HbF at birth is temporarily protective (no B in fetal
- Microcytic, hypochromic RBC and target hemoglobin)
cells on blood smear
- Hemoglobin electrophoresis findings: - Microcytic, hypochromic target cells and nucleated RBC

• Increased HbA2 to 5% (normal - Hemoglobin electrophoresis findings:
2.5%)- main finding • No HbA (no B chain)
• Increased HbA2 and HbF
• Increased HbF to 2% (normal 1%)
• Slightly decreased HbA

8. What are target cells?
- Normally, hemoglobin is present mainly on edge of RBC giving it biconcave shape with central pallor. In

target cells, there are some hemoglobin in center giving central darkness (like bull's eye target practice).

- MOA- due to reduced hemoglobin in edge of RBC, the membrane in center gets floppy and some
hemoglobin comes to stay there.

9. What are presentation of beta thalassemia major?
- Bad erythropoiesis with severe anemia
- Extravascular hemolysis as spleen will phagocytose these RBC
- Massive erythroid hyperplasia

○ Expansion of hematopoiesis into skull and facial bone marrow - crew cut X-ray of skull and
chipmunk face
Extramedullary hematopoiesis - hematopoiesis in liver and spleen (hepatosplenomegaly)

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○ Extramedullary hematopoiesis - hematopoiesis in liver and spleen (hepatosplenomegaly)
○ Risk of aplastic crisis with parvovirus B19 (parvovirus affects erythrocyte precursors and shuts

down RBC production. In normal person, shutting down of RBC production for a week or so won't
matter. For pt with beta thalassemia major, they can't afford even a single day of RBC production
loss. They depend on every drop of RBC)

Fig: chipmunk face (left) and crewcut appearance (right) seen in massive erythroid hyperplasia
10. What is treatment of beta thalassemia major? What's it's complication?

- Treatment is chronic blood transfusion; splenectomy for swollen spleen and iron chelation to prevent
secondary hemochromatosis

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5.3 Macrocytic anemia

1. What is macrocytic anemia? What are it's causes?
- Macrocytic anemia is anemia with MCV (mean corpuscle volume) >100. RBC precursor doesn't

divide much and the RBC end up being big.
- Causes:

○ Megaloblastic anemia (anemia with big cells) - disruption in production of DNA precursors
results in quick cytoplasmic development relative to nuclear development:
 Folate deficiency
 Vit B12 deficiency
 Orotic aciduria
 Folate and Vit B12 needed for DNA precursor synthesis

○ Alcoholism
○ Liver disease, drugs (ex- 5-FU)

Megaloblastic anemia
Vit B12 and Folate deficiency

2. Describe relationship between folate and Vit B12.
- Folate comes to body as methylated tetrahydrofolate (M-THF).
- THF is the active form. M-THF donates it's methyl group to Vit B12. Vit B12 then gives methyl

group to homocysteine. Homocysteine now becomes methionine.

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3. What is presentation of macrocytic anemia due to folate or vit B12 deficiency?
- Megaloblastic anemia (impaired division of RBC precursors)
- Hypersegmented neutrophil with >5 lobes (normal is 3-5 lobes) (impaired division of granulocytic

precursors)
- Megaloblastic changes in rapidly dividing cells (ex - intestinal epithelial cells)

Fig: hypersegmented neutrophils with large RBC (aka macroovalocyte) on the left- classic
finding in megaloblastic anemia

4. What is difference between megaloblastic anemia and macrocytic anemia that's not
megaloblastic?

- In macrocytic anemia that's not megaloblastic, hypersegmented neutrophils and megaloblastic
changes (ex - large intestinal epithelial cells) won't be seen. Large RBC will be seen.

5. Compare dietary information of folate and vit B12.

Folate Vit B12

Food Dark green vegetable and food Animal derived proteins

Absorption Jejunum Ileum

Deficiency Develops in months as body Takes years to develop due to large hepatic
stores are minimum storage

Causes of - Poor diet (alcoholics, old) - Pernicious anemia (autoimmune destruction
deficiency - Increased demand (pregnancy, of parietal cells of stomach) - most common
cancer, hemolytic anemia) - Using proton pump inhibitor
- Folate antagonists - Pancreatic insufficiency (Vit B12 won't be free
(methotrexate - inhibits DHFR) from R-binder)
- Damage to terminal ileum (Chron's,
Diphylloborthium latum)
- Vegans (dietary deficiency rare otherwise)

6. Compare clinical and lab findings of folate and Vit B12 deficiency.

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6. Compare clinical and lab findings of folate and Vit B12 deficiency.

Folate deficiency Vit B12 deficiency

- Macrocytic RBC and - Macrocytic RBC and hypersegmented neutrophils
hypersegmented neutrophils

- Glossitis (inflammation of - Glossitis

tongue - due to less turnover of

tongue cells)

- Low serum folate - Low serum vit B12

- Increased serum homocysteine - Increased serum homocysteine (increases risk for
(increases risk for thrombosis) thrombosis)

- Normal methylmalonic acid; no - Increased methylmalonic acid in myelin cells which impairs

neuro symptoms spinal cord myelinization resulting in subacute combined

degeneration of spinal cord

7. What are two important reactions that Vit B12 participate in?
- DNA precursor synthesis (with folate)
- Conversion of methylmalonic acid to succinyl Co. A

8. Why do we see increased serum homocysteine in folate deficiency?
- Normally, dietary folate (M-THF) gives it's methyl group to Vit B12 which in turn gives it to

homocysteine. Homocysteine now becomes methionine.
- The reaction won't happen in folate deficiency and we'll see increased serum homocysteine.

9. Why will methylmalonic acid be increased in Vit B12 deficiency?
- Because Vit B12 is necessary to convert methylmalonic acid to succinyl Coenzyme A.

10. Describe absorbtion of Vit B12 in gut (HY)
- R-binder protein from saliva binds to Vit B12. The complex will travel till small bowel. There's Vit
B12 is set free by pancreatic proteases.
- The free Vit B12 binds to intrinsic factor secreted by parietal cells of stomach.
- This complex will go to ileum and get absorbed there.

11. What are 3 P's of parietal cell?
- Proton pump - they pump proton to stomach to make it acidic
- Pink in histology (chief cells appear blue)
- Pernicious anemia if they get damaged - makes IF

Orotic aciduria

Defn - Inability to convert orotic acid to uridine monophosphate (UMP) that leads to
accumulation of orotic acid (defect in de-novo purine synthesis pathway)
- AR inheritence

Presentati - Megaloblastic anemia in children refractive to folate and vit B12
on - Failure to thrive, developmental delay

- Orotic acid in urine but no hyperammonemia

Treatment - UMP to pass the mutated enzyme

Nonmegaloblastic macrocytic anemia

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Defn - Macrocytic anemia where DNA synthesis is unimpaired
- RBC macrocytosis without hypersegmented neutrophils

Causes - Alcoholism
- Liver disease
- Hypothyroidism
- Reticulocytosis

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5.4 Normocytic anemia

1. What is normocytic anemia? What are two types based on etiology?

 Normocytic anemia is decreased RBC mass with normal-sized RBC (MCV - 80-100 µm3)

 Types:
o Peripheral destruction of RBC (will have reticulocyte >3%)
 Extravascular hemolysis (RBC destroyed by liver, spleen and lymph)
 Intravascular hemolysis (RBC destroyed within blood vessel)
o Underproduction of RBC (no increased reticulocytes)

2. What are reticulocytes?
 They are young RBC released from bone marrow to replace dead RBC
 Seen as large cells with bluish cytoplasm (due to RNA) on blood smear
 Normally, 1-2% of RBC die every day and are replaced by reticulocytes.

3. How can reticulocyte be falsely elevated in anemia? How is reticulocyte count corrected?
 Reticulocytes are measured as percent of total RBC. In anemia, total RBC goes down. It will

elevating the percent of reticulocytes.
 It’s corrected by multiplying reticulocyte percent x hematocrit/45.

Total RBC Total % of HCT Corrected
Reticulocyte reticulocyte reticulocyte

Normal pt 100 2 (given) 2%
(given)

Anemic 50 (given) 2(given) 4% 23 (given) 4 x 23/50 = 2%
pt

In this example, if we only look at % of reticulocyte, it looks as if bone marrow is normal. But from
corrected reticulocyte, we know that anemic pt’s bone marrow is not producing adequate
reticulocytes.

4. How can reticulocyte count differentiate cause of anemia?

If corrected reticulocyte >3% If corrected reticulocyte <3%

Good marrow response (suggest peripheral Poor marrow response (suggest
destruction as cause of anemia) underproduction of RBC as cause of anemia)

Extravascular vs intravascular hemolysis
1. What is extravascular hemolysis? What happens to broken down RBC?
• Hemolysis done by reticuloendothelial system (macrophage in liver, spleen and lymph nodes)
• Globin is broken to AA; Iron is recycled
• Protoporphyrin is converted to unconjugated bilirubin which is carried by albumin to liver (its fat
soluble). It’s conjugated in liver and excreted to bile.

2. What are lab and clinical finding of extravascular hemolysis?
• Anemia with splenomegaly
• Jaundice due to unconjugated bilirubin (too much bilirubin to be conjugated by liver)
• High risk for bilirubin gallstones
• Marrow hyperplasia with corrected reticulocyte >3%

3. What happens in intravascular hemolysis? What's the presentation?

RBC disorders Page 7.1

3. What happens in intravascular hemolysis? What's the presentation?
• RBC is destroyed in blood vessels. Unlike macrophage breaking down hemoglobin to bilirubin,

hemoglobin simply leaks out to blood.
• Hemoglobin is carried by haptoglobin. Haptoglobin is not present a lot. So, pt will quickly have

hemoglobinemia and hemoglobinuria (hemoglobin water soluble)
• Hemosiderinuria after few days (HY) - hemoglobin in urine is picked up by renal tubular cells. Iron

is recycled back and stored as hemosiderin. Renal tubular cells slough off (just like skin cells) and
hemosiderin will be seen in urine.
• Presentation:

Immediate After few days

- Decreased serum haptoglobin - Hemosiderinuria

- Hemoglobinemia

- Hemoglobinuria

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5.5 Normocytic Anemia with Extravascular Hemolysis

Hereditary spherocytosis
1. What is hereditary spherocytosis? What are the mutations?
- In the disease, tethering proteins that attach RBC cytoskeleton to RBC membrane are mutated.
RBC membrane blebs and are lost over time. RBC becomes more spherical.
- Most common mutations are in proteins - ankyrin, spectrin, or band 3.
2. What are clinical and lab findings?
- See spherocytes - RBC becomes round instead of disc shaped (loss of central pallor)
- High RDW (some cells have lost tons of membrane and some only a little bit)
- high mean corpuscular hemoglobin concentration (MCHC) - high concentration of hemoglobin as
cells are getting small
- Extravascular hemolysis findings
○ Anemia - spherocytes can't move through splenic sinusoids well and are eaten by splenic
macrophages (this is main problem) - having spherocytes isn't bad
○ Splenomegaly (overworked spleen)
○ Jaundice with unconjugated bilirubin, high risk for bilirubin gallstones

Fig: spherocytes with high RDW (note variability in RBC sizes and loss of central pallor)
3. What is one feared complication?
- Increased risk of aplastic crisis with parvovirus B19 infection of erythroid precursors
4. How is diagnosis of hereditary spherocytosis made?
- Osmotic fragility test - cells bursts in hypotonic solution very easily because cell doesn't have

much membrane to expand out
5. What's it's treatment?
- Splenectomy (having spherocytes isn't problem, spleen eating them is problem)
- Anemia resolves but spherocytes persist and Howell-Jolly bodies are seen
6. What's Howell-Jolly bodies?
- Some RBC's are impefectly made with little nucleus or nuclear material left. It's job of spleen to

take them out or kill the defective RBC. Howell-Jolly bodies are RBC with nuclear remnant. It
indicates splenic dysfunction

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Fig: Howel Jolly bodies

Sickle cell disease
1. What causes sickle cell anemia?
• It’s caused due to mutation in B chain of hemoglobin that changes glutamic acid (hydrophilic) to
valine (hydrophobic). Think GingiVa - from Glutamic acid to Valine
• Disease is due to homozygous recessive mutation. Haterozygotes are protected against
plasmodium falciparum malaria

Phenotype Hemoglobin composition

Sickle cell disease (homozygous mutation) 90% HbS, 8% HbF, 2%HbA2, no HbA

Trait (one mutated and one normal B chain) 55% HbA, 43% HbS, 2% HbA2
• HbS – sickle cell hemoglobin (in α2β2 protein, both copies of β are mutated)

2. What is pathogenesis of sickle cell anemia?
• HbS polymerizes when deoxygenated (reversible). The polymers accumulate into needle shaped

structures and make RBC sickle cell.
• Sickling and de-sickling damages membrane leading to both intravascular and extravascular

hemolysis (spleen eats damaged RBC); sickled RBC cause vaso-occlusion; massive erythroid
hyperplasia to replace RBC.
• Sickling increases with hypoxemia, dehydration and acidosis.
• HbF protects against sickling. Kids protected for first few months of life.

3. What's treatment of sickle cell disease?
- Hydroxyurea - it increases level of HbF. It protects against sickling

4. What are presentations of sickle cell disease?
• Extravascular hemolysis – RBCs being sickle shaped and non-sickle cell repeatedly damages

membranes. Reticuloendothelial system removes these damaged RBC.
○ Anemia
○ Jaundice with unconjugated hyperbilirubinemia
○ Increased risk for bilirubin gallstones

• Intravascular hemolysis – due to membrane damage
○ Decreased haptoglobin
Hemoglobinemia, hemoglobinuria

RBC disorders Page 8.2

○ Hemoglobinemia, hemoglobinuria
○ Hemosiderinuria after few days
○ Target cells - hemoglobin leaks out due to membrane damage and extra membrane

produces target cells
• Massive erythroid hyperplasia (to compensate hemolysis and anemia):

○ Hematopoiesis in skull and facial bones (crewcut on X-ray and chipmunk face)
○ Extramedullary hematopoiesis (in liver, giving hepatomegaly - pt don't have spleen so don't

get splenomegaly)
○ Risk of aplastic crisis with parvo B19 infection

Fig: chipmunk face (left) and crewcut appearance (right) seen in massive erythroid
hyperplasia
• Extensive sickling leads to vaso-occlusion

5. What are some physical findings in sickle cell disease due to vaso-occlusion?
• All findings based on infraction
• Dactylitis – due to vasoocclusive infaracts in bones – common in infants
• Autosplenectomy – shrunken, fibrotic and calcified spleen

○ Increased risk of encapsulated organism infection (staph aureus, strep pneumo,
haemophilus influenza)

○ Salmonella paratyphi osteomyelitis (encapsulated) - most common cause of osteomyelitis
is staph aureus; in sickle cell, it's salmonella.

○ Howel-Jolly bodies on blood smear - nucleated RBC
• Acute chest syndrome (vaso-occlusion of pulmonary microcirculation)

○ Often precipitated by pneumonia
○ Presents with chest pain, SOB, lung infiltrates
• Pain crisis
• Renal papillary necrosis – presents as gross hematuria and proteinuria

Fig: vaso-occlusive complications of sickle cell disease - from left to right - autosplenectomy - small
calcified spleen; renal papillary necrosis; dactilytis; Howel-Jolly bodies

6. What’s the most common cause of death in sickle cell patients?
Kids Hemophilus influenza infection
Adults Acute chest syndrome

RBC disorders Page 8.3

Adults Acute chest syndrome

7. What is sickle cell trait?
• Haterozygote carriers of sickle cell mutation have sickle cell trait. They have one mutated and one

normal beta chain.
• HbS (both beta chain mutated) makes <50% of total hemoglobin because HbA is slightly more

efficiently made than HbS

8. What are presentations of sickle cell trait?
• Generally asymptomatic as RBC with <50% HbS don’t sickle
• Renal medulla problems:

○ Due to extreme hypoxia and hypertonicity in medulla, sickling occurs.
○ Presents as microscopic hematuria and decreased ability to concentrate urine due to

microinfraction of medulla.

9. What are lab findings in sickle cell disease and trait?

Sickle cell disease Sickle cell trait

Sickle cell and target cells seen in blood Don’t see sickle cell or target cells
smear

Metabisulfite screen +ve (cells with any Metabisulfite screen +ve
amount of HbS are sickled by the
screen)

• Confirm amount and presence of HbS with Hb electrophoresis

Sickle cell disease 90% HbS, 8% HbF, 2% HbA2, no HbA

Trait 55% HbA, 43% HbS, 2% HbA2

Hemoglobin C
1. What is hemoglobin C?
- Hemoglobin C is formed due to mutation in Beta chain of hemoglobin (autosomal recessive).
- Glutamic acid is changed to lysine (lyCne for hemoglobin C) - think Gingiva - Glutamic acid to
lyCine as gingiva is C shaped)
- Less common than sickle cell disease

2. What is presentation of hemoglobin C?
- Mild anemia due to predominant extravascular hemolysis
- HbC crystals on blood smear (HY)

Fig: HbC crystals characteristic of hemoglobin C (the rods)
Pyruvate kinase deficiency

Pathophys - RBC depend on glycolysis to synthesize ATP
- Bad pyruvate kinase means ATP deficiency that affects lots of processes in RBC

RBC disorders Page 8.4

Blood - Echinocytosis (echino means hedgehog or sea urchin) - also see this in
smear hyperlipidemia, uremia, hemolytic anemia, hypomagnesemia, hypophosphatemia
etc

- Contrast Echinocytosis which looks similar to acanthocytosis

Fig: acanthocytosis - see in hyperlipidemia or liver damage due to RBC membrane
damage

RBC disorders Page 8.5

5.6 Normocytic Anemia with Intravascular Hemolysis

Paroxymal nocturnal hemoglobinuria (PNH)
1. How do cells in blood protect themselves from complement system?

- DAF (decay accelerating factor) and MIRL (membrane inhibitor of reactive lysis) are present in
RBC, WBC and platelets. They block complement fixation in RBC. DAF decays C3 convertase.

- Protein called GPI (glycosylphophatidylinositol) anchors MIRL and DAF to cells.

2. What causes paroxysmal nocturnal hemoglobinuria?
- It's acquired (not congenital mutation) defect in myeloid stem cell so that GPI is absent in myeloid

stem cells. Complement fixation lyses RBC, WBC and platelets

3. What is presentation of PNH?
- Symptoms are seen paroxysmally at night because breathing becomes swallow and mild acidosis

activates complement at night.
- Dark urine early morning
- Hemoglobinura, hemoglobinemia
- Hemosiderinura seen few days after hemolysis (after tubular cells slough off)
- Thrombosis - due to release of clotting factors from lysed platelets

4. What is main cause of death in PNH?
- Thrombosis of hepatic, portal or cerebral veins - due to release of clotting factors from lysed

platelets

5. What are complications of PNH?
- Fe deficiency anemia (due to chronic loss of Hb in urine)
- Acute myeloid leukemia (10% of patients)

6. How is diagnosis of PNH made?
- Screening - Sucrose test
- Confirmatory test - acidified serum test or flow cytometry to test lack DAF (aka CD55) on RBC

Glucose-6-Phosphatase dehydrogenase (G6PD) deficiency - aka favism
1. What is G6PD deficiency? What's it's pathophysiology
- X linked recessive disorder (see in men) that results in low half-life of G6PD.
- G6PD is first enzyme in pentose phosphate pathway and is required to make NADPH. NADPH is
important to reduce oxidative stress.
- G6PD deficiency presents as increased oxidative stress including hemolytic anemia.

2. What are two major variants of G6PD deficiency?

African variant Mediterranean variant

- Mildly reduced half-life of G6PD - Markedly reduced half-life of G6PD

- Mild intravascular hemolysis with oxidative - High intravascular hemolysis with oxidative

RBC disorders Page 9.1

- Mild intravascular hemolysis with oxidative - High intravascular hemolysis with oxidative
stress stress

3. What protective role does being carrier of G6PD deficiency have?
- Protection against falciparum malaria

4. What's histology finding of G6PD deficiency anemia?
- Heinz bodies - precipitation of Hb due to oxidative stress
- Bite cells - Caused due to removal of Heinz bodies from RBC by macrophage

5. What are some causes of oxidative stress?
- Sulfa drugs
- Antimalarial drugs
- Fava beans

6. What's presentation of G6PD deficiency anemia?
- Hemoglobinuria and back pain (hemoglobin is nephrotoxic) hours after exposure to oxidative

stress

7. What is diagnosis of G6PD deficiency?
- Screening - Heinz preparation - need to see heinz body
- Confirm - enzymatic studies (don’t do it during acute phase because RBC lacking G6PD are already

dead).

Immune hemolytic anemia (IHA)
1. What causes immune hemolytic anemia?
- IgG or IgM mediated destruction of RBC.

2. Differentiate between IgG vs IgM mediated IHA.

IgG mediated IHA IgM mediated IHA

- Hemolysis is usually extravascular - tagged RBC are eaten - Hemolysis is usually extravascular-
tagged RBC are eaten

- Warm agglutination - IgG binds to RBC in warm temp - Cold agglutination - IgM binds to
(central parts of body). RBC in cold temp (extremities).
- Splenic macrophage phagocytose tagged RBC leading to - RBC can inactivate complement, but
formation of spherocytes (when RBC are eaten only C3b acts as opsonin for splenic
halfway, remaining RBC makes sphere) macrophages - see spherocytes

- Associated with: - Associated with:
- Lupus - pt have anti-blood Ab • Mycoplasma pneumoniae

RBC disorders Page 9.2

- Lupus - pt have anti-blood Ab • Mycoplasma pneumoniae
- CLL (chronic lymphocytic lukemia) - cause hemolytic (cold agglutination test)
anemia
- drugs (classically penicillin and cephalosporins) - drug • infectious mononucleosis (+ve
induces autoantibody production or Ab can bind to drug- haterophile agglutination - Ab
RBC complex made against sheep blood)

- Treatment • CLL
• Stop offending drug
• Steroids
• IVIG (distract spleen)
• Splenectomy - spleen is the one that eats RBC

3. How do you diagnose IHA? Indirect coombs test

Direct coombs test - Confirm presence of anti-RBC Ab in
patient's blood
- Confirms presence of Ab or complement coated
RBC - Anti IgG and test RBC(normal RBC) are
mixed in patient serum (agglutination
- When anti-IgG or anti-complement Ab are added occurs only if serum Ab are present)
to pt RBC, agglutination occurs only if RBC are
already coated with IgG or complement

- Most important test for IHA

Microangiopathic hemolytic anemia
1. What is microangiopathic hemolytic anemia (hemolysis in small blood vessel)?
- It's hemolysis that occurs due to vascular pathology (usually something in blood vessel breaks the
RBC)

2. What are some etiologies?
- Presence of microthrombi

○ TTP- thrombotic thrombocytopenic purpura
○ HU- hemolytic uremic syndrome
○ DIC
○ HELLP - hemolysis elevated liver enzyme and low platelet
- Prosthetic heart valves - crush RBC
- Aortic stenosis - crush RBC

3. What is blood smear finding?
- Schistocytes (broken RBC) - aka helmet cells

Fig - schistocytes (helmet cells) - has mostly two acute angle and loss of about 50% of RBC;
contrast bite cells that have usually >2 acute angles and almost entire volume of RBC is present.

Malaria
1. How does malaria cause anemia?
- Plasmodium infects and replicates in RBC. RBC ruptures as merozoites (a stage in their lifecycle)

RBC disorders Page 9.3

- Plasmodium infects and replicates in RBC. RBC ruptures as merozoites (a stage in their lifecycle)
are released

- Spleen also consumes infected RBC causing some extravascular hemolysis
Erythroblastosis fetalis

Defn - Maternal IgG crossing placenta and attacking fetal RBC (ex - Rh -ve mother carrying
two consecutive Rh +ve babies)

Present - See extramedullary hematopoiesis (ex - in liver) because RBC are damaged

RBC disorders Page 9.4

5.7 Normocytic Anemia due to Underproduction

1. What is anemia due to underproduction?
- It's anemia caused due to low RBC production by bone marrow.
- Characterized by low corrected reticulocyte (<3%)

3. What are some etiologies of anemia due to underproduction?
- Renal failure - decreased erythropoietin production by peritubular interstitial cells
- Anything that causes microcytic and macrocytic anemia
- Damage to bone marrow precursor cells - ex parvovirus B19

4. Describe how parvovirus B19 infection leads to anemia.
- Parvovirus B19 infects progenitor RBC and temporarily halts erythropoiesis.
- It causes significant anemia in setting of preexisting marrow stress (ex - sickle cell)
- Treatment is supportive (infection is self-limited)

Aplastic anemia
1. What is aplastic anemia?
- Aplastic anemia is damage to hematopoietic stem cell resulting in pancytopenia (anemia,
leukopenia, thrombocytopenia)

2. What are etiologies of aplastic anemia?
- Etiologies:

○ Drugs or chemicals, radiation
○ Viral infection - parvo B19, HIV, EBV, HCV
○ Autoimmune damage
○ Fanconi anemia (inherited DNA repair defect that causes bone marrow failure) - high risk of

leukemia later

3. What are biopsy finding in aplastic anemia?
- Empty fatty marrow

Fig: Aplastic anemia (left) vs normal bone marrow on right. Note the depletion of marrow and
replacement by fat globules on left.

4. What's treatment for aplastic anemia?
- Immunosuppression for cases with abnormal T cell activation
- Stop causative drugs
- Blood transfusion and marrow stimulating factors (erythropoietin, GM-CSF, G-CSF)
- May need bone marrow transplant

Myelophthisic process
1. What are melophthisic process?
- Pathologic processes that replace bone marrow (ex - cancer)
- Hematopoiesis is impaired resulting in pancytopenia

RBC disorders Page 10.1

Lymphoid tissue anatomy

1. Spleen
- PALS (periarteriolar lymphatic sheath) - has T cells (drink tea with pals) - in white pulp
- Germinal center - has B cells - in white pulp

RBC disorders Page 11.1

Chapter 6: White Blood Cell Disorders

CMAP summary

WBC disorders Page 1.1

Chromosome with genes

1. Ch 8 - c-myc ( protein in Ras- MAPK pathway)
2. Ch 11 - B globulin of Hb (1 allele per chromosome), Cyclin D1
3. Ch 14 - Ig heavy chain
4. Ch 15 - retinoic acid receptor
5. Ch 16 - alpha globulin of Hb (2 alleles per chromosome)
6. Ch 18 - Bcl2 (anti-apoptotic protein)

WBC disorders Page 2.1

6.1 Leukopenia and Leukocytosis

1. Draw out the development of different blood cell lines.

2. What happens in leukopenia or leukocytosis?
- Leukopenia - low WBC (penia = lack of)
- Leukocytosis - high WBC
- Usually, increase or decrease is in one particular cell line

Leukopenia
1. List the differences between neutropenia and lymphopenia.

Neutropenia Lymphopenia

Decreased circulating neutrophils Decreased circulating lymphocytes

Causes: Causes:
- Drug toxicity- Chemotherapy - Damage - Immunodeficiency - HIV, DiGeorge syndrome
stem cell and decreased production of - High cortisol - Induces apoptosis of lymphocytes
WBC, specially neutrophil - Autoimmune destruction - Lupus
- Severe infection- Neutrophils move to - Whole body radiation - Lymphocytes are highly
tissue sensitive to radiation; lyphopenia is earliest change to
- Lupus emerge after whole body radiation

Treatment: GM-CSF or G-CSF

*Corticosteroids cause neutrophilia but lymphopenia and eosinopenia. They cause sequestering of eosinophils in
lymph nodes, induce apoptosis of lymphocytes, and impair adhesion of neutrophils to vessel wall.
Leukocytosis
1. What are the causes of leukocytosis.
- Leukocytosis is increased WBC count.

Causes

Neutrophilic - Bacterial infection or tissue necrosis (also see left shift which have decreased Fc receptors
leukocytosis (CD16)
- High cortisol state - impairs neutrophil adhesion; marginated pool is released to blood
(marginated pool - leukocytes that are attached to vessel wall and hang there like bats)

Monocytosis - Chronic inflammatory state (autoimmune and infectious)
- Malignancy

Eosinophila - Allergic reaction (type I hypersensitivity)
- Parasitic infections
- Hodgkin lymphoma (increased IL5)

Basophilia - Classically seen in chronic myeloid leukemia (CML) - (HY)

WBC disorders Page 3.1

Basophilia - Classically seen in chronic myeloid leukemia (CML) - (HY)

Lymphocytic - Viral infection
leukocytosis - Bordetella pertussis (whopping cough)- (exception because bacteria usually increase
neutrophil)

Infectious mononucleosis
1. What causes mono?
- EBV (most common), CMV (less common)

2. What's presentation of EBV infection?
- Mono has classic triad of lymphadenopathy, fever and exudative pharyngitis
- Other:

○ T cell hyperplasia
 Lymphadenopathy due to hyperplasia in paracortex (location IMP to know)
 Splenomegaly due to hyperplasia in periarterial lymphatic sheath (PALS)

○ Hepatitis

3. Describe the screening test for mono (monospot test)?
- Test detects haterophile antibodies (haterophile = loves others) - detects IgM Ab that cross-react with horse or

sheep RBC
- Test turns positive after 1 week of infection

4. What are two cases where person has mono but monospot test is negative?
- Mono is caused by CMV (only EBV mono will have positive monospot test)
- Test is done within 1 week of infection

5. What's definitive diagnosis for EBV infection?
- Serologic test for EBV viral capsid Ag.

6. What are complications of EBV infection?
- Splenic rupture (due to splenomegaly) - avoid contact sports for 1 year
- Rash is exposed to ampicillin (pharyngitis of group A strep is treated by penicillin)
- Virus dormant in B cell:

○ Risk for B cell lymphoma, esp in immunodeficiency
○ Recurrence of mono

WBC disorders Page 3.2

6.2 Acute Leukemia

1. What defines acute leukemia? What are its types?
- Acute leukemia is presence of >20% blasts in the bone marrow (normal is 1-2%). Blasts indicate

myeloid or lymphoid stem cell (undifferentiated cells).

- Types:
○ Acute lymphoblastic leukemia (ALL) - presence of >20% lymphoblast stem cell
○ Acute myeloid leukemia (LML) - presence of >20% myeloid stem cell

2. What is presentation and clinical findings in acute leukemia?
- Normal hematopoiesis is disturbed:

○ Anemia (tired)
○ Thrombocytopenia (bleeding)
○ Neutropenia (infection)
- Note that WBC count is high due to presence of lots of blasts in blood
- Blast cell appear as large immature cells with punched out nucleoli.

Fig: blast cells with punched out nucleolus (as if punched via punching machine) - notice lots of
them (gives high WBC count)
Acute lymphoblastic leukemia
1. How do you distinguish if acute leukemia is from myeloblast of lymphoblast?
Acute lymphoblatsic leukemia +ve nuclear staining for TdT (a DNA polymerase)
Acute myelogenous leukemia +ve cytoplasmic staining for myeloperoxidase (MPO)
2. What is epidemiology of ALL?
- Most commonly seen in children
- Associated with down syndrome (usually >5 years)
3. Distinguish the two types of acute lymphoblastic leukemia.

WBC disorders Page 4.1

3. Distinguish the two types of acute lymphoblastic leukemia.

B-ALL (B-acute lymphoblastic leukemia) T-ALL (acute lymphoblastic lymphoma)

Characterized by lymphoblast (TdT+) that Characterized by lymphoblasts (TdT+) that express
express CD10, CD19, and CD20 (markers of CD2-CD8; lack CD10
B cells)

Excellent response to chemotherapy (give Excellent response to chemotherapy (give

prophylaxis dose in scrotum and CSF) prophylaxis dose in scrotum and CSF)

- Usually present in teenagers as mediastinal
(thymic) mass - cancer called lymphoma because of
cells make a mass

4. What are two types of B-ALL?
- T (12;21) - good prognosis - usually seen in children
- T (9;22) (aka Philadelphia + ALL) - poor prognosis - usually seen in adults

Picmonic for ALL

Pt popn - Affects <15 years (quincenera scene)

Prognosis - t(12;21) has better prognosis (girl with 1 wand and tutu looking at her reflection)
- Excellent response to chemotherapy - chemo girl kissing on the last figure
- Give prophylactic chemo to testes and CNS - bottom left figure guy hitting enemy
on head and testes

Markers - TDT +ve (explode with TNT)
- CALLA +ve (villan with collar - bottom middle pic)

Presentatio - Thymic mass (medistinal arrow) for T-ALL
n

Acute Myeloid leukemia
1. What is acute myeloid leukemia?
- Presence of immature myeloid cells >20% in bone marrow
- Myeloid stem cell characterized by +ve cytoplasmic staining for myeloperoxidase (MPO)
- Crystal aggregate of MPO may be seen as Auer rods

WBC disorders Page 4.2

Fig: Aure rods inidicating MPO presence (diagnosis for AML)

2. What is epidemiology of AML?
- Mostly affects old people - (50-60 years)

3. What are different types of AML?

Acute Cause - t(15;17) translocates retinoic acid receptor (RAR) to
promyelocytic chromosome 17. Bad receptor blocks maturation of
leukemia WBC and promyelocytes (blasts) accumulate.

Acute monocytic Treatmen - All trans retinoid acid (ATRA - vit A derivative) - it
leukemia (MPO - t can bind to bad retinoic acid receptor. (this signaling
ve)
important for development of myeloblasts)

Complica - DIC (promyelocytes contain numerous primary
tion granules that increase risk for DIC).

○ Blasts characterstically infiltrate gums

Acute - Associated with Down syndrome (usually seen <5 years)
megakaryoblastic
leukemia (MPO -
ve)

Myelodysplastic syndrome
7. What is myelodysplastic syndrome?
- Dysplasia of myeloid stem cells. It increases risk of AML.
- Presents as
○ >3% but <20% blasts (if it's >20%, it's acute leukemia)
abnormal maturation of cells and increased blasts because cells can't fully differentiate-

WBC disorders Page 4.3

○ abnormal maturation of cells and increased blasts because cells can't fully differentiate-
that's why increased risk of AML

○ Most pt die from infection or bleeding (some progress to AML)
○ Cytopenia and hypercellular bone marrow (cells are stuck in bone marrow and not going

out)
- Ex - Pseudo-Pegler-Huet anomaly - neutrophils with bilobed nuclei typically seen after

chemotherapy

Fig: Pseudo-Pegler-Huet anomaly

WBC disorders Page 4.4