Mimicry of surreptitious diuretic ingestion and the ability to make a genetic diagnosis

Gitelman's syndrome, also known as "hypocalciuric variant of Bartter's synd rome", is a cause of chronic hypokalemia and hypomagnesemia in adults. A sp ecific gene has been found responsible for this disorder, encoding the thia zide-sensitive NaCl coporter (TSC) in the distal convoluted tubule. We desc ribe a psychiatric patient with chronic symptomatic hypokalemia and hypomag nesemia whose electrolyte disturbances were subsequently misdiagnosed as an acute alcohol and benzodiazepine withdrawal syndrome, as chronic diuretic abuse and as a classical Bartter's syndrome. Finally, genetic investigation revealed the presence of mutations in the SLC12A3 gene leading to the prop er diagnosis of Gitelman's syndrome. We emphasize that Gitelman's syndrome should be suspected in every hypokalemic patient with biochemical resemblan ce of diuretic ingestion, especially when repeated toxic screens for diuret ics are negative. The ability to make a molecular-genetic diagnosis can be of practical benefit in confusing clinical settings.