A case of xanthinuria

Abstract

We report a patient with xanthinuria who showed hypouricemia during management of diabetes mellitus and hypertension.
The patient was an 81 - years - old female. Serum and urinary uric acid were not detectable. Xanthinuria was suspected, and oxypurine level in serum and urine was measured at several laboratories. Serum xanthine level was 2.05,3.85 and 2.83 μg/ml, serum hypoxanthine level was 1.73,2.09 and 2.27 μg/ml, urinary xanthine level was 23.3 and 12.64 mg/dl, urinary hypoxanthine level was 3.81 and 1.86 mg/dl, which indicate a significant increase in urinary excretion of oxypurine. Xanthine oxidase activity in duodenal mucosa was not detectable at one laboratory, it was found to be extremely low compared with control at another laboratory. Thus, a diagnosis of xanthinuria of the patient was established. Although uric acid and oxypurine levels of serum and urine were measured in 28 relatives, neither xanthinuria nor its heterozygote was found.