Tubular defects in patients forming calcium-containing stones

The study of renal function, primarily the tubular function, in 55 patients with idiopathic, recurrent renal stones showed a large number of abnormalities. 49% of the patients, especially the women were affected. The most common defect was a reduced acidification capacity of varying degrees of severity in 64% of the woman and in 20% of the men. Impairment of the acidification capacity of the distal tubule was found in 18% and of the proximal tubule in 11% of the patients. Inability to dilute the urine after water loading was found in 17% and tubular proteinuria also in 17% of the patients. Most patients with an impaired tubular function had a severe stone disease. The defects in acidification and dilution capacity ought to be of pathogenetic importance for stone formation and should be considered in the selection of preventive therapy.