In general, the etiology of hypokalemic, hypochloremic, metabolic alkalosis is straightforward, since the most commonly occurring causes are easily recognized on clinical grounds. In some cases, such as the one described herein, however, the cause is not readily apparent, and a comprehensive systematic approach is recommended.

REPORT OF A CASEÌý A 35-year-old obese practical nurse was hospitalized because of unexplained hypokalemia persisting for several months, despite oral supplementation of as much as 120 mEq of potassium chloride elixir daily. She repeatedly denied vomiting, diarrhea, and diuretic or laxative use.Physical examination results were unremarkable except for slight proximal muscle weakness. Laboratory data included the following values: serum sodium, 140 mEq/L; potassium, 2.7 mEq/ L; chloride, 91 mEq/L; bicarbonate, 35 mEq/L; creatinine, 0.9 mg/dL; and calcium, 9.7 mg/dL. Arterial blood pH was 7.50, and Paco₂ was 45 mm Hg. Urinary values for potassium ranged from 30 to 50 mEq/L and