Metabolic factors in urolithiasis: a study in Brazil

Clinical and biochemical data were obtained from 50 patients in whom stones form and 20 controls to set up and test a screening procedure for detecting metabolic abnormalities related to the formation of urinary calculi and to provide a preliminary estimate of the frequency of these disorders in our area. A comparison between patients in whom stones form and controls in terms of the quantitative biochemical parameters evaluated (serum calcium, uric acid and inorganic phosphate, and urine calcium, uric acid, inorganic phosphate, oxalic acid, xanthine and alpha-amino-nitrogen) showed a significant difference only with respect to excretion of urinary oxalate by adults, which was higher in patients in whom stones form. Metabolic disorders were detected in 15 adult patients with stones. Of these patients 9 had isolated hyperoxaluria, 3 had incomplete renal tubular acidosis, 1 had idiopathic hypercalciuria, 1 had heterozygous cystinuria and 1 had idiopathic hypercalciuria associated with heterozygous cystinuria. These results suggest a high frequency of metabolic abnormalities in patients in whom stones form in our area, so that the wider use of the screening used here may benefit a large number of patients with preventive and therapeutic measures.