HEREDITARY XANTHINURIA IN 2 PATIENTS - A RARE CAUSE OF HYPOURICEMIA -2 OBSERVATIONS

BACKGROUND: Hypouricemia can be observed in uncommon situations as in our two patients with hereditary xanthinuria. CASE REPORTS: in the fir st case, hereditary xanthinuria was discovered in a 36-year-old man wh en routine tests revealed hypouricemia. In the second case, a 76-year- old woman, hypouricemia was also a fortuitous discovery. She had major xanthinuria and a radiotranslucid lithiasis in the right kidney. DISC USSION: Hereditary xanthinuria is characterized by hypouricemia, low u rinary urate excretion and increased concentration of xanthine and to a lesser extent hypoxanthine. The disease results from a defect in xan thine oxidase and is considered to be transmitted by autosomal recessi ve heredity. This rare metabolic disorder is more often asymptomatic a nd detected by routine chemistry. Development of xanthine lithiasis is directly related to the low solubility of xanthine and is the main co mplication oi the disease, occurring in 30-40% of patients, There is n o effective treatment and the only useful measure is to prevent xanthi ne urolithiasis by maintaining urinary output above 2 l/day. (C) 1998, Masson, Paris.