Endocrine Abstracts

We describe a case of chronic hypokalaemia secondary to Gitelman's syndrome. A 17 year female presented with a 1 year history of lethargy, muscle cramps and intermittent generalised abdominal pain. She took no regular medications and had no significant past medical history or family history. She was normotensive with a significant hypokalaemic, metabolic alkalosis. Sodium=135mmol/l, potassium=2.7mmol/l, creatinine=75micromol per litre, bicarbonate=36mmol/l. The hypokalaemia persisted despite a six week trial of oral potassium supplementation. Investigation results: 24 hour urinary potassium excretion=40mmol/l, 24 hour urinary calcium excretion=1.3mmol/l, serum magnesium=0.7mmol/l, hyper-reninaemic hyperaldosteronism, urinary laxative and diuretic screens persistently negative. A diagnosis of Gitelman's syndrome was made clinically, which was subsequently confirmed on genetic analysis. Several adjustments of treatment with potassium sparing diuretics were required to achieve eukalaemia. Currently, on treatment with spironolactone 200mg the patient is asymptomatic; potassium=4.3mmol/l, bicarbonate=35mmol/l. Gitelman's syndrome is caused by loss of function mutation of the sodium choride cotransporter of the distal convoluted tubule (NCCT). The diagnosis should be suspected in every hypokalaemic patient with biochemical indices indicative of diuretic ingestion, especially when toxicology screens are negative.