Sjögren's syndrome in one of two sisters with idiopathic renal hypouricemia.

Concomitance of idiopathic hypouricemia and Sjögren's syndrome is reported. A 37-year-old Japanese woman with Sjögren's syndrome and her 39-year-old sister without this syndrome both had extremely low levels of serum uric acid. Markedly increased urinary excretion of uric acid and poor response to the pyrazinamide suppression test revealed that the hypouricemia in these sisters was caused by a defect in the pre-secretory reabsorption of uric acid. It is categorized as idiopathic renal hypouricemia than hypouricemia rather secondary to Sjögren's syndrome. Thus, idiopathic renal hypouricemia should be considered even in cases with autoimmune diseases.