CORRECTED CLEARANCE IDENTIFIES UNDEREXCRETION OF URIC ACID IN A GOUTY KINDRED: 64

Abstract

Both the rate and the efficiency of uric acid excretion were evaluated in a 28 year old gouty woman and in 16 additional members of her family. Mid-morning, spot blood and urine specimens were obtained from three generations of the kindred, living in Washington, Montana, British Columbia and Alaska. The excretion rate of uric acid, calculated per deciliter glomerular filtrate (GF), was normal in 15 family members. One person fell slightly above and one below two standard deviations from normal mean values of 0.37 ± 0.12 mg/dl GF in women and 0.39 ± 0.10 mg/dl GF in men.Uric acid clearance was determined as an index of excretion efficiency. Since normal clearance is aa exponential function of the serum urate, all values were "corrected" to a serum level of 5 mg/dl. Values from the kindred were compared to control groups of healthy, young men and women in whom the relative uricosuria of women was confirmed and quantified: the mean corrected uric acid clearance in women (9.6 ± 2.7 ml/min) being 133% of that in men(7.2 ± 1.9 ml/min). Corrected clearance of uric acid was significantly depressed in four of six family members with gout and in two additional subjects one of whom was hyperuricemic but still asymptomatic. Using these simple methods, we identified and quantified inefficient uric acid excretion which appears to obey autosomal dominant transmission.