Renal acidifying ability in subjects with recurrent stone formation.

To determine the incidence of an acidification defect in men in whom calcium stones form and its relationship to parathyroid function 120 such patients were given an acute dosage of 0.1 gm. per kg. oral ammonium chloride and circulating immunoreactive parathyroid hormone was determined. The subjects were divided into 2 groups, according to normal or high parathormone levels. Group 1 consisted of 46 men in whom immunoreactive parathyroid hormone was less than or equal to 60 mulEq. per ml. and group 2 consisted of 74 men with immunoreactive parathyroid hormone greater than 60 mulEq. per ml. Of 8 men in whom the urine failed to acidify to less than a pH of 5.3, 3 were from group 1 and 5 were from group 2. None of the patients had an active urinary tract infection. There was no difference in minimal urine pH among the patients in whom the urine acidified normally regardless of immunoreactive parathyroid hormone. The incidence of abnormal acidification in our population was 6% and all of these patients had the incomplete form of renal tubular acidosis. These findings have important therapeutic implications.