aetiology and pathogenesis

Last reviewed 01/2018

The largest series, reported from Finland, suggests autosomal recessive inheritance.

The precise nature of the underlying defect is not known. Chloride ions appear to be allowed to leak into the intestinal lumen, causing a watery diarrhoea, with chloride loss in excess of sodium, and consequent potassium depletion. The result is dehydration and a severe systemic electrolyte imbalance - characteristically hypokalaemia, hypochloridaemia and alkalosis. This is a most unusual pattern for a child with persistent diarrhoea.

Chronic hypovolaemia itself causes a series of secondary effects. An increase in renin and angiotensin concentrations, with secondary hyperaldosteronism, results in vascular changes in the kidney resembling those seen in hypertension, even when these patients have normal blood pressure. Chronic potassium depletion results in impaired functioning of renal tubular and intestinal absorptive cells.