Renal function in gout. IV. An analysis of 524 gouty subjects including long-term follow-up studies.

Renal function studies were performed in 524 gouty subjects, including follow-up studies at intervals up to 12 years in 112 of them. In 49 subjects, the glomerular filtration rate was less than 70 ml/min and Curate:glomerular filtration rate ratio tended to rise as the glomerular filtration rate decreased, reflecting a relatively stable urate excretion over varying filtered urate loads. The increment in Tsurate:glomerular filtration rate was small with spontaneous Purate between 7 and 9 mg/100 ml. It was modest with Purate up to 10 mg/100 ml. The increment in Tsurate:glomerular filtration rate became much higher beyond Purate of 10 mg/100 ml. Urinary urate levels above 800 mug/min, designated as excess urate excretion, occurred more commonly in subjects with Purate above 9 mg/100 ml, and with better preserved renal function. Tophi were more frequently observed in subjects with low glomerular filtration rate and proteinuria; but incidence of urolithiasis seemed to be less affected by a decrease in the glomerular filtration rate. Hyperuricemia alone had no deleterious effect on renal function as evidenced by follow-up studies over periods up to 12 years. Deterioration of renal function was largely associated with aging, renal vascular disease, renal calculi with pyelonephritis or independently occurring nephropathy. In only very few instances was diminished renal function ascribable to gout alone.