Hyponatremia

Question 1

Hyponatremia - Causes

Answer 1

Urinary sodium > 20mmol/L

Sodium depletion, renal loss (patient often hypovolaemic):
Diuretics: thiazides, loop diuretics
Addison’s disease
Diuretic stage of renal failure

Patient often euvolaemic:
SIADH (urine osmolality > 500 mmol/kg),
hypothyroidism

Urinary sodium < 20 mmol/l

Sodium depletion, extra-renal loss:
Diarrhoea, vomiting, sweating
burns, adenoma of rectum

Water excess (patient often hypervolaemic and oedematous):
Secondary hyperaldosteronism: heart failure, liver Cirrhosis
Nephrotic syndrome
IV dextrose
Psychogenic polydipsia