Tetany and rhabdomyolysis due to surreptitious furosemide--importance of magnesium supplementation.

Diuretics may induce hypokalemia, hypocalcemia and hypomagnesemia. While severe hypokalemia may cause muscle weakness, severe hypomagnesemia is associated with muscle spasms and tetany which cannot be corrected by potassium and calcium supplementation alone (1,2). Surreptitious diuretic ingestion has been described, mainly in women who are concerned that they are obese or edematous. Symptomatic hypokalemia has been reported in such patients (3-7) and in one case hypocalcemia was observed (8), but the effects of magnesium depletion were not noted in these patients.