ABSTRACT
A patient with Bartter's syndrome manifested hypomagnesemia in addition to hypokalemia. Under conditions of maximal free water production, he had a fractional distal solute reabsorption of 0.65, a value consistent with a renal defect in sodium chloride reabsorption in the thick ascending limb of the loop of Henle. This is also the site of 65% to 70% of urinary magnesium reabsorption. With magnesium supplementation and amiloride, the urinary potassium decreased and the serum potassium increased. Atrial natriuretic peptide concentrations in the plasma were low. Evaluation of family members showed five of nine offspring had hypokalemia with no disorder in the parents, an apparent autosomal recessive mode of inheritance. This is a US government work. There are no restrictions on its use.
