Hypouricemia in a 41-year-old male is reported. His serum urate was 0.4-0.8 mg/dl Through laboratory studies and roentgenology, known causes other than renal tubular dysfunction were ruled out as a mechanism of his hypouricemia. Detailed clearance study was performed to clarify his urate homeostasis. His fractional excretion of urate (ratio of urate to creatinine clearance), exceeding 100% in the basal state, slightly increased to 114% by benzbromarone and decreased to 99% by the serial administration of pyrazinamide. This finding demonstrates that his hypouricemia was due to a combined type of renal urate reabsorption defect.
We also reviewed 69 reported cases of renal hypouricemia and discussed the relevance of serum urate levels and types of tubular defects.
