The Metabolic Defect Responsible for Uric Acid Stone Formation*

The composition of a urinary tract stone often may be related to increased urinary concentration of one or more of the stone constituents or to characteristic hydrogen ion concentrations in the urine (1). Thus calcium phosphate and calcium oxalate are the major constituents of stones in patients with hypercalciuria, cystine stones are limited to patients with increased urinary cystine due to cystinuria (2), and calcium magnesium ammonium phosphate stones are generally found in patients with constantly alkaline urine due to ureasplitting infections. Boyce and King (3) have suggested that formation of an organic matrix may be the primary abnormality in stone formers and that the mineral content of the stone may reflect merely the chemical composition of the urine at the time the matrix was formed. This paper concerns studies of certain chemical factors in patients known to form uric acid stones.