Renal tubular reabsorption of chloride in Bartter's syndrome and other conditions with hypokalemia.

Fractional distal chloride reabsorption was measured in 8 patients with Bartter's syndrome, 8 patients with comparable degrees of hypokalemia of different etiologies and 7 normal subjects during maximal diuresis induced by an intravenous infusion of 5% dextrose in water. A low fractional distal chloride reabsorption (0.55 +/- 0.01) was found only in patients with Bartter's syndrome, whose serum potassium concentrations ranged between 1.2 and 3.1 mEq/l. Non-Bartter's syndrome hypokalemic patients had serum potassium concentrations between 2.4 and 3.2 mEq/l (p NS when compared to patients with Bartter's syndrome) but their fractional distal chloride reabsorption was 0.88 +/- 0.33, significantly higher (p less than 0.001) than that of patients with Bartter's syndrome. Normokalemic control subjects had a fractional distal chloride reabsorption of 0.86 +/- 0.01, higher than patients with Bartter's syndrome (p less than 0.001) but not significantly different from patients with hypokalemia. These results suggest that there is no effect of serum potassium concentration on fractional distal reabsorption of chloride in man. Hypokalemia of a moderate to severe degree is not accompanied by obligatory renal chloride loss except in Bartter's syndrome. Chloruresis is a specific feature of Bartter's syndrome rather than an effect of hypokalemia.