Tetany induced by hypokalemia in the absence of alkalosis.

A 36-year-old patient developed tetany manifested only by a positive Trousseau's sign and with a negative Chvostek's sign 8 weeks after gastric bypass surgery for obesity. The usual causes of tetany (hypocalcemia, hypomagnesemia and alkalosis) were absent. The only possible etiology found was hypokalemia. Previous cases of hypokalemia induced tetany reported were always accompanied by alkalosis. Its absence in our patient makes this case unique and determines that hypokalemia per se in the absence of alkalosis may be a cause of tetany. It is suggested that the Trousseau's sign should be investigated in patients with severe potassium deficiency.