Electrolytes Disturbances
Sodium Major cation of the ECF
The total body Na – 5000 mmol.
Plasma Na conc. 137 – 147 mmol/l
ICF conc. – 5 mmol/l
Distribution 44% in ECF
47% in bone
9% in ECF.
Sodium
Daily intake – 3 – 5g.(50 –90 mEq ) Normal urinary loss 10 – 90
mEq/day < 1 mEq/ day in conditions of
reduced intake or extra renal loss
Other sources of Na loss
Sweat 10 – 60 mEq/ day
300 mEq in individuals unacclaimatised to hot climates
Intestine 0 – 20 mEq/day
Hyponatraemia
Common causes
1) GI loss e.g. obstruction 2)Inappropriate ADH secretion
GI loss obstruction
H+ ion Paralytic ileus
K+ ion loss Fistulae Diarrhoea
Inappropriate ADH secretion
Oat cell Ca
CNS tumours
Trauma
Hyponatraemia – C. F. Neurological – irritability, lethargy,
c convulsions,
coma
Associated water loss-dehydration
. Investigations
Hct,
plasma proteins,
creatinine,
urea
Investigations Plasma Na low or normal
Urinary Na
< 10mmol/l in extra renal loss,
>20mmol/l in renal loss.
Treatment oral
Isotonic saline
Hypertonic saline
Hypernatraemia
Causes Over infusion of saline
Water loss
Water loss increased sweating
Diabetes insipidus
Hyperadrenalism
Hypernatraemia – C.F.
Facial puffiness, edema, weight gain, CCF, increased osmalality
ICF dehydration
brain - confusion irritability, convulsions coma
Treatment P/O period stop saline,
if due to lack of water, infuse 5% Dextrose
Potassium
ICF cation
Total body K(TBK) = 2500 mmol,
98% ICF – 160 mmol/l,
2% ECF
Plasma K is an important determinant of TBK ,
reduction of 1mmol/l = 200 – 300mmol of TBK
Potassium
Commonest site – skeletal muscle
ECF K- important for neuromuscular function
Acidosis - K out of the cell – hyperkalaemia
Alkalosis - hypokalaemia
Potassium
Daily intake – 50 – 100 mmol
Sources – fruits, milk, honey
K excreted through kidney Renal response to K depletion
slower
Alkalosis - increased renal loss
Acidosis - decreased renal loss
Trauma - increased K excretion
Hypokalaemia
Causes: Loss through the GI excretions –
diarrhoea, fistulas, villous adenomas, ureterosigmoidostomy
Deficient administration – IVfluids
Hyperaldosteronism
Insulin administration
Hypokalaemia . C . F.
Neuromuscular > muscular weakness
Arrhythmias
Ileus
Polyuria
ECG > flattening of T waves, prominent U waves, sagging of ST segment
Treatment oral K,
I/V should not exceed 20 mmols/hour
Hyperkalaemia
Inadequate excretion –
renal
C.F GI symptoms CVS – peaked T, wide T, cardiac
arrest
GI symptoms nausea, vomiting, int. colic, diarrhoea
CVS peaked T,
wide T,
cardiac arrest
Treatment I/V Ca,
combination of HCO3, glucose and insulin,
dialysis
Magnesium
Intracellular divalent cation
Normal serum Mg. – 0.8 to 1.2 mmol/l
Total – 1000 mmols.
Slowly exchangeable
Distribution Bone – 67%,
ICF – 31%,
ECF – 1%
Magnesium
Absorbed
jejunum
ileum
Excretion – kidney. Kidney has remarkable ability to conserve
Function –most of the enzyme systems
Deficiency – along with K & Ca deficiency
Normal daily intake – 10 mmol
Sources – nuts, peas seed gram
Hypomagnesemia
Causes: Malabsorption,
intestinal fistula,
pancreatic insufficiency,
massive bowel resection,
Causes:
biliary diversion,
prolonged N/G suction, hypoparathyroidism, TPN
Severe hypomagnesemia - blocks release of PTH – hypocalcaemia
Increased aldosterone - K loss -hypokalaemia
Hypomagnesemia C. F.
Paraesthesia,
irritability,
mental confusion
Hypocalcaemic features
Hypokalaemic features – arrhythmia etc
Hypermagnesmia in severe renal failure.
Treatment hypokalaemia & hypocalcaemia to
be corrected.
TPN – supplement Mg.
Trace elements
Copper,
Manganese,
Zinc,
Selenium
Trace elements Exact role not defined
Deficiency > rash in TPN patients
Supplementation required in TPN
Replacement of ongoing lossesComposition of GI secretions
401005145500Biliary Fistula
120755140700Pancreatic Fistula
159015601500Gastric Juice (Fasting)
301025101500Saliva
HCO3
(mg mol/l)
Cl(mg mol/l)
K(mg mol/l)
Na (mg mol/l)
Vol (ml)
Locality
Replacement of ongoing lossesComposition of GI secretions
459025120500-15000
DiarrhoealStool
HCO3
(mg mol/l)
Cl(mg mol/l)
K(mg mol/l)
Na (mg mol/l)
Vol (ml)
Locality
30452080300Prox.Colostomy
30458115500Ileostomy