Incidence and clinical importance of renal tubular defects in recurrent renal stone formers.

Renal tubular function was studied in 318 consecutive recurrent renal stone formers. Impaired acidification capacity was found in 19% of the patients, and tubular proteinuria in 13% of the patients. Most of the patients with defective acidification of the urine had the incomplete form of renal tubular acidosis (RTA), rpoximal and distal defects being equally common. The incidence of impaired acidification was much higher in the female (38%) than in the male (13%) stone formers. A further analysis of the clinical picture in patients with acidification defects revealed a more severe stone disease than among other stone formers. Characteristic findings were an early onset, multiple recurrences were an increased need for surgery. Stone analyses showed a high frequency of calcium phosphate stones. Investigations of renal tubular functions appear to be a valuable adjunct in the evaluation of recurrent renal stone disease.