[Hereditary xanthinuria. A clinical case report].

A case of hereditary xanthinuria in a 68-year-old man with congestive heart failure and alcoholic liver disease is presented. Urolithiasis and muscular symptoms were absent, and the metabolic error was revealed by hypouricemia, hypouricosuria and excess of xanthine and hypoxanthine excretion in urine. Xanthine oxidase (EC 1.2.3.2) activity in liver tissue was absent, confirming the diagnosis of xanthinuria.