Chronic hypokalaemia of adults: Gitelman's syndrome is frequent but classical Bartter's syndrome is rare.

We evaluated 27 adult patients with chronic hypokalaemia (K+ = 2.9 +/- 0.2 mmol/l), documented over at least 5 years, in whom the cause of the hypokalaemia had not been clarified in spite of previous testing. In 15 patients it was possible to establish a diagnosis by a thorough outpatient workup (diuretic abuse (n = 5), surreptitious vomiting (n = 8), laxative abuse (n = 1), renal tubular acidosis (n = 1)). Commonly utilized tests such as measurements of plasma renin activity, plasma aldosterone, and urinary potassium concentration proved not to be useful in the differential diagnosis of these patients. In contrast the following were diagnostically important: in surreptitious vomiting the hypochloraemia, the mild renal insufficiency, and the extremely low urinary chloride concentration; in diuretic abuse the high urinary concentration of chloride together with repeatedly positive toxicology screens for diuretics; in laxative abuse the high stool weight and extremely low urinary sodium concentration. In the remaining 12 patients none of these diagnoses applied and further tests for suspected Bartter's syndrome were done in the hospital.(ABSTRACT TRUNCATED AT 250 WORDS)