Kimiyoshi Ichida

Primary Renal Uricosuria

Publisher Summary This chapter focuses on primary renal uricosuria, or hereditary renal hypouricemia, which is a common inherited and heterogeneous disorder. Hereditary renal hypouricemia is a common overexcretion-type hypouricemia and heterogeneous disorder and the feature is a persistent marked hypouricemia due to high urinary urate excretion above about 25% of fractional excretion of urate (Feua) characterized by impaired tubular urate transport. Renal hypouricemia has been classified into five types by the response to the antiuricosuric drug pyrazinamide, and the uricosuric drug, probenecid. The types include a defect with an attenuated response to both pyrazinamide and probenecid, a defect with a response to pyrazinamide and no response to probenecid, a defect with a response to both drugs and probenecid inducing urate clearance over the GFR, a defect with an attenuated response to pyrazinamide and no or paradoxical antiuricosuric response to probenecid, and a defect without any response to either drug. Urate transporter 1 (URAT1), one of the organic anion transporter families, was discovered to be a transporter for urate reabsorption in exchange of lactate at apical membrane of a proximal tubular cell. Exercise-induced acute renal failure (ARF) in renal hypouricemic patients is characterized by patchy renal vasoconstriction observable by enhanced abdominal computed tomography scan. The prognosis for a single episode of exercise-induced ARF is generally favorable, though the long-term prognosis is unknown. Specific treatment for exercise-induced ARF has not been established. Restriction of exercise may be effective for prophylaxis; however, it is not entirely appropriate, because exercise-induced ARF does not always follow exercise and is believed to stem from other events or condition such as dehydration.