RESUMO
The aim of the study was to establish the frequency of tubular dysfunction in 59 patients with nephrolithiasis, of whom 52 had unilateral and 7 bilateral calculosis. Before the study urinary infection was cured in all patients. Renal function was normal in all subjects. Hypercalcaemia was present in 8 patients, and hypercalciuria in 17 subjects. Phosphate clearance (CPO4) was increased in 40 patients, and had the same number of patients, decreased tubular reabsorbtion of phosphate (TRP). In 31 patients increased CPO4 and decreased percent of TRP was present. Renal threshold phosphate concentration was decreased in 17 patients. High fraction excretion of sodium was observed in 37 patients, while urine sodium level was higher than normal only in 4 patients. Decreased ability of renal acidification of urine was found in 5 patients, and decreased renal concentration ability in 10 subjects. The most common finding in the observed patients was the phosphate excretion defect usually accompanied with defect of calcium excretion, and defect of urine acidification.