Renal function in gout: V. Factors influencing the renal hemodynamics

Renal hemodynamics as measured by inulin clearance (C inulin) and para-aminohippurate clearance ( Cpah) was evaluated in 149 patients with primary gout over intervals of two to 22 years. In over 30 per cent of the patients plasma urate was >10 mg/dl and urinary uric acid >800 mg/min. A linear trend in decreasing frequency of hyperuricemia and excessive uricosuria is significantly related to the patient's age at the onset of gout. Group I consisted of 84 patients with uncomplicated gout in both clearance studies. C inulin and Cpah were somewhat lower in patients ≥ 50 years of age with longer duration of gout. Further reduction in clearances was minimal at the second clearance study in intervals of approximately 10 years. Group II included 27 patients who had no associated disease at the time of the first clearance study but in whom associated disease had developed by the time of the second clearance study. A striking reduction in C inulin and Cpah was noted, especially in those 50 years old or above. There were 38 patients in group III with associated diseases at the time of both clearance studies. They had lower C inulin and Cpah at the time of the first study, particularly the older patients. Further reduction during the second study was less striking than that in group II. Analyses of variance suggest that various coexisting vascular diseases with associated nephropathy have the most significant impact on the status of renal function in gout, with aging the second most important and duration of gout, the third.