Familial Renal Hypouricemia due to Isolated Tubular Defect

Abstract

Renal hypouricemia, that is hypouricemia due to a renal abnormality reflected in increased uric acid clearance, is a rare condition, either inborn or acquired. When genetically determined, it usually appears in association with other tubular defects, such as in the Fanconi (1) and Hartnup syndromes (2) and Wilson’s disease (3). Recently, we reported on a familial renal hypouricemia, associated with idiopathic hypercalciuria and decreased bone density (4). Renal hypouricemia due to an isolated renal tubular defect has been reported in a few subjects (5,6), but to our knowledge only once as a familial syndrome (7). We presently describe another family with renal hypouricemia, in whom the renal tubular defect relates to the handling of uric acid exclusively. The propositus, a 27-year-old Iraqian-born Jewish female, was followed at the Hematology Clinic since 1969, when a diagnosis of toxoplasmosis was established. All blood chemistry and hematological tests were normal, except for serum uric acid which ranged from 1.1 to 1.9 mg%. Urinary uric acid excretion on a regular diet ranged from 815–1008 mg/24 h, as determined colorimetrically (8). Serum ceruloplasmin level and urinary copper excretion were within the normal range.