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Term Definition
Standard This is a measure of the ‘metabolic component’ of an acid
bicarbonate base disturbance. The value is the theoretical value of
arterial plasma bicarbonate assuming the PCO 2 ,
temperature and oxygen saturation to be normal.
Strong One which is fully dissociated:
electrolyte − +
e.g. a strong BZ −→ B + Z
acid for a strong acid;
BH −→ B + H +
−
Unlike the situation with weak electrolytes and weak
acids, there is no equilibrium.
Strong ion The SID is a parameter derived by Peter Stewart in his
difference so-called ‘quantitative’ approach to understanding
(SID) acid-base disturbances. Numerically, SID is a measure of
unmeasured strong anions such as lactate. Compare SID
with anion gap.
Tonicity The effective osmotic potential of a solution. Where two
solutions are separated by a selectively permeable
membrane, the net flow of liquid from one fluid
compartment to the other is determined by the relative
concentrations of non-diffusible chemical species present
in the solutions. Relative tonicity of body fluids is the
‘driving factor’ affecting fluid movement between
interstitial fluid and intracellular fluid. Compare tonicity
with Osmolality and Osmolarity. Note that urea is a
diffusible solute (except in the renal tubule) so it has little
or no impact on osmotic pressure across cell membranes,
but urea is a contributor to measured osmolality.
Transudate A fluid which passes by a process of ultrafiltration from the
blood stream into a tissue space. Examples include CSF
and saliva.
Weak One which is not fully dissociated. A chemical equilibrium
electrolyte; is established between the ionised and un-dissociated
e.g. a weak forms with the relative concentrations favouring the
acid un-dissociated form:
−
AX −→ A + X +
←−
for a weak acid;
−
AH −→ A + H +
←−
The position of equilibrium lies heavily to the left and so
+
the concentration of free protons (H ) is very small.
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328 Appendix
Appendix II: Reference ranges
Reference ranges for commonly measured analytes are to be used as a
guide for interpretation only, as actual values quoted may vary between
laboratories.
Analyte Range
Plasma
Anion gap 11–16 mmol/L or 15–20 mmol/L
(depending on formula used)
Bicarbonate 23–28 mmol/L
Calcium (total) 2.25–2.55 mmol/L
Chloride 97–107 mmol/L
Glucose (fasting) 3.5–5.5 mmol/L
Magnesium 0.8–1.1 mmol/L
Osmolality 285–295 mmol/kg
Potassium 3.5–4.5 mmol/L
Sodium 135–145 mmol/L
Urea 3.0–7.0 mmol/L
Whole arterial blood
pH 7.35–7.45
PCO 2 4.8–5.8 kPa
PO 2 12–14 kPa
Base excess −2to +2 mmol/L
Standard bicarbonate 22–26 mmol/L
Urine output per 24 hours
Sodium 100–200 mmol
Potassium 50–100 mmol
Calcium 4.5–6 mmol
Creatinine 8–12 mmol
Volume Variable according to fluid intake as liquids
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Index
f signifies a Figure t signifies a Table
1,25 dihydroxy vitamin D3, 93, 118, angiotensin, 110f , 111f
119f , 120f angiotensin converting enzyme
methods for quantification, (ACE), 110f , 111f
147–149 angiotensinogen, 110f , 111f
11- -hydroxy steroid anion gap, 42, 274
dehydrogenase, 96–97, 190 corrected for albumin
concentration, 283
acid dissociation constant, k a and metabolic acidosis (DKA),
pk a , 19, 221 288t
acidosis ANP, see Natriuretic peptide
see Respiratory acidosis anti-diuretic hormone (ADH),
and Non-respiratory acidosis 93–94f ,95f
acids, 18 see also SIADH
metabolic, 229–231 aquaporin, 95
renal excretion of, 237–239 A TOT , 258, 265
Addison’s disease
and hyperkalaemia, 188 base excess, 261
and hyponatraemia, 180 bicarbonate, 130, 232, 233–236
albumin and the Henderson-Hasselbalch
estimation of, 151 eqn, 234, 273
osmotic effects, 84–86 BNP, see Natriuretic peptide
aldosterone, 96–97f body fluids
and intercalated cells, 112 chemical composition of, 28, 29f ,
alkalosis 30t
see Respiratory alkalosis distribution of, 83–87
and Non-respiratory alkalosis turnover of, 36t
ammonia and ammonium ion, 239, volume of, 34, 35f ,36t
240–241, 255 and daily intake of fluid, 37
amperometry, 139t Bohr effect, 251–252
Essential Fluid, Electrolyte and pH Homeostasis, First Edition. Gillian Cockerill and Stephen Reed.
© 2012 John Wiley & Sons, Ltd. Published 2012 by John Wiley & Sons, Ltd.
329
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330 Index
boiling point, elevation of, 15 diarrhoea
buffers, 23, 221–223 and acidosis, 291–292
physiological, 232 diuretics, 169–170
and metabolic alkalosis, 299–300
CSF see cerebrospinal fluid and potassium loss, 190
calcium, 115 divalent metal transporter (DMT),
corrected calcium concentration, 125
116, 163 drugs and toxins
homeostasis, 116f , 117–118 and acidosis, 291
methods for quantification, see also diuretics and alkalosis
147–149
see also hypercalcaemia and Eisenmann-Nikolsky equation
hypocalcaemia (ISEs), 144
calcium-sensing receptors, 118 electrical neutrality, 5f
carbon dioxide see also Gibbs-Donnan
as a volatile acid, 229, 265 equilibrium, 39, 40f ,41
see also partial pressure of electrochemical gradients, 5, 9,
carbonate dehydratase 39–42
see carbonic anhydrase see also Gibbs-Donnan equilibrium
carbonic anhydrase (carbonate equilibrium constant, k eq ,9
dehydratase) erythropoietin, 93
and kidney nephron, 239–240, extracellular fluid (ECF), 3, 28–29f
243f
and red blood cell, 251 factitious results, 160–163
cerebrospinal fluid (CSF), 31, 32t familial benign hypocalciuric
chloride, 130 hypercalcaemia (FBHH), 194
see also anion gap and strong ion ferritin, 123, 200
gap ferroportin, 125
colligative properties of solutions, freezing point, depression of, 15
12, 14–15
compartments, 3, 28–33, 35f Gibbs-Donnan equilibrium, 39, 46,
compensation, 280t, 280f –282f 48
Conn’s syndrome, 175 glutaminase, 241, 243f
cortisol, 96–97f glycyrrhizinic acid, 190
see also Addison’s disease and
Cushing’s disease haemochromatosis, 201
cryoscopy , 136f haemoglobin
Cushing’s disease as a buffer, 232–233, 251–252
and hypokalaemia, 189 gas transport, 248–249f
salt gain, 175 haemosiderin, 123
Henderson-Hasselbalch equation,
diabetes insipidus, 174 24, 223
diabetes mellitus and the carbonic acid/bicarbonate
and acidosis, 288 system, 273, 279–282
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Index 331
hepcidin, 125–6 k a see acid dissociation constant
hydrostatic pressure, 54 ketogenesis, 255–256f
see also Starling’s hypothesis k w see ion product of water
hypercalcaemia
aetiology, 193 lactate, 230f , 255
case studies, 194–196 and acidosis, 288–289f
hyperchloraemia and strong ion difference,
and acidosis, 278f 262–263
and strong ion difference (SID), lymphatics, 53f
262–263
hyperkalaemia magnesium
aetiology, 186–187 homeostasis, 121
case studies, 187–188 hyper_ and hypomagnesaemia,
pH, 238 198t–199
hypernatraemia, 170, 171t methods for quantification, 148
aetiology, 173–175 membrane
case studies, 176–178 gradients, 4, 44f
hypocalcaemia transport, 4f ,51f ,90f , 112
aetiology, 196 minerals, 102, 103t
case studies, 197–198 mixed acid-base disturbance, 274,
hypokalaemia 278
aetiology, 189–190 mole fraction, 15
case studies, 190–192
hyponatraemia, 170, 171t, natriuretic peptide, 95, 98f ,99t
179–180, 181–183 Nernst equation, 143
non-respiratory acidosis, 274
interstitial fluid (ISF), 29f ,30t, 33, (= metabolic acidosis), 277, 278f ,
84–85 287–292
intracellular fluid (ICF), 3, 29f ,30t, compensation for, 281f
33, 85–87 example case studies, 293–296
pH of, 228 non-respiratory alkalosis, 274
intravenous infusions, 157–158f (= metabolic alkalosis), 277–8,
ion product of water, k w and pk w ,9, 297–298, 299–301
10 compensation for, 282f
ion pumps, 50–53, 90f
ion selective electrodes, 138–146 oedema, 113f –114, 168–169
ionophores, 139–141f osmol gap, 58
iron, 123, 126f osmolality, 57
disorders of homeostasis, 200–201 see also osmolarity and tonicity
methods for quantification, osmolarity, 57
149 see also osmolality and tonicity
isotonic, 45,46f osmometry, 134–137
osmoregulation and renal function,
juxtaglomerular cells, 110f 93–99
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osmosis, 4, 43, 55 respiratory disorders, 303–304t,
oxygen dissociation curve, 249f 305–306
example case studies, 307–311
parathyroid hormone (PTH), 117,
120f selectivity coefficient (ISEs), 144
parathyroid hormone related peptide Siggard-Anderson, Ole, 257
(PTHrP), 118 significant change, 165
partial pressure of carbon dioxide SIADH (Syndrome of Inappropriate
(PCO 2 ), 244, 245t ADH secretion), 180
and respiratory acidosis, 274, sodium, 106–107, 109
304 and fluid distribution, 167
and respiratory alkalosis, 274 sodium pump, 51–52, 90f
measurement of, 268 standard bicarbonate, 260
partial pressure of oxygen (PO 2 ), Starling’s hypothesis, 54f , 84–86
244, 245t Stewart , Peter, 258–260, 262–267
phosphate, 131 strong ion difference (SID), 258,
as a buffer, 232 260, 262–264
methods for quantification, strong ion gap (SIG), 265
147–149 Syndrome of Inappropriate ADH
pk a , see acid dissociation constant secretion (SIADH), 180
potassium, 107–108, 184–185
potentiometry, 138, 139f , 140f tonicity, 58
proteins as buffers, 21–22, 130–131 see also osmolality
pseudohyperkalaemia, 161–162 total body water, 28–29f
pseudohyponatraemia, 163 see also Body Fluids
transferrin, 123–124
Rapoport-Leubering shuttle, and transferrin receptor, 125
249–250f
reference values see Appendix valinomycin, 139
renal dysfunction vapour pressure, 14f
and acidosis, 290 vitamin D
renal threshold, 91 see 1,25 dihydroxy vitamin D3
renal tubular acidosis, 290t vomiting
renin, 93, 110f and metabolic alkalosis, 299
respiratory acidosis, 274, 276, 280f
example case studies, 307–308 water
respiratory alkalosis, 274, 277, 281f distribution, 34, 43, 50, 53f
example case studies, 309–311 polarity, 9