Electrolytes Abnormalities Summary

Electrolytes Abnormalities Summary

17/3/11

Arvind Rajanami – Nepean Written Course

Oxford Handbook of Critical Care (2nd Edition)

GENERAL APPROACH

- intake:

- redistribution:

- output: urinary

non-urinary

-> upper GI

-> mid GI

-> lower GI

-> other - skin, bleeding, sweat, RRT

POTASSIUM

Hyperkalaemia

- intake: oral intake, blood transfusion

- redistribution: acidosis, rhabdomyolysis, tumour lysis

- output: urinary - RTA type 4, renal failure, adrenal insufficiency, DM, K+ sparring diuretics

Hypokalaemia

- intake: inadequate intake

- redistribution: alkalosis, hypoMg2+, glucose infusion, periodic paralysis, beta-agonists

- output: urinary -steroids (ex or en), DKA, hyperaldosteronism, Cushings, RTA, diuretics

non-urinary

-> upper GI - vomiting

-> mid GI - fistula

-> lower GI - diarrhoea

-> other - sweat, burns, bleeding, RRT

MAGNESIUM

Hypermagnasaemia

- intake: usually iatrogenic (Mg infusion)

- redistribution:

- output: urinary - renal failure increases risk of accumulation

Hypomagnasaemia

- intake: TPN, malabsorption, alcoholism

- redistribution: insulin, hungry bone syndrome

- output: urinary - RTA, diuretics, polyuria from any cause

non-urinary

-> upper GI - NG loss

-> lower GI - diarrhoea

CALCIUM

Hypercalcaemia

- intake: Ca2+, vitamin A or D, hypoMg2+, hypovolaemia, TPN

- redistribution: immobilization, malignancy, hyperparathyroidism, sarcoid, lithium, adrenal insufficiency, endocrine causes (thyrotoxicosis, acromegaly, phaeo)

- output: urinary – thiazides

Hypocalcaemia

- intake: Ca2+, vitamin D, phenytoin (increased metabolism of vitamin D)

- redistribution: alkalosis, citrate toxicity, hyperphosphataemia, pancreatitis, tumour lysis syndrome, rhabdomyloysis, decreased bone turnover, hypoparathyroidism, drugs (bisphosphonates,PPI’s, SSRI’s, gentamicin)

- output: urinary - ethylene glycol, cis-platin, protamine, loop diuretics

non-urinary- bleeding, plasmapheresis, citrate RRT

PHOSPHATE

Hyperphosphataemia

- intake:

- redistribution:

- output: urinary

non-urinary

-> upper GI

-> mid GI

-> lower GI

-> other - skin, bleeding, sweat, RRT

Hypophosphataemia

- intake: malnutrition, phosphate binders, vitamin D, malabsorption, TPN

- redistribution: refeeding syndrome, insulin in DKA

- output: urinary - diuretics, osmotic diuresis, hyperparathyroidism, proximal tubular dysfunction (Fanconi’s syndrome)

non-urinary

-> upper GI

-> mid GI

-> lower GI - diarrhoea

-> other - sweat, burns, sepsis, bleeding

SODIUM

- different than all the rest.

- must think of mainly redistribution of H2O

To sort out:

(1) Osmolality

(2) Volume assessment

(3) Where is the H2O being lost from?

HYPOTONIC

Hypovolaemic

-> urinary (urinary Na+ high) – diuretics, osmotic diuretics, RTA, salt wasting, mineralocorticoid deficiencies

-> non-urinary (urinary Na low)

-> upper GI - vomiting

-> mid GI - pancreatitis, bowel obstruction

-> lower GI - diarrhoea, bowel preparation

-> other - skin, bleeding, sweat

Euvolaemic

-> SIADH (most common)

-> psychogenic polydipsia

-> hypotonic IVF therapy

-> adrenal insufficiency

-> hypothyroidism

Hypervolaemic

-> CHF

-> cirrhosis

-> nephrotic syndrome

-> hypothyroidism

-> pregnancy

-> TURP syndrome

ISOTONIC (pseudohyponatraemia)

- high proteins

- high lipids

HYPERTONIC

- glucose

- mannitol

- sorbitol

- radiocontrast

- advanced renal disease (need to correct osmolality = measured osmolalilty – urea)

Jeremy Fernando (2011)