Studies on Metabolism of Uric Acid in Renal Disease

—Hycruricemia in Chronic Glomerulonephritis—

Abstract

On 203 cases of chronic nephritis, statistical studies were performed on serum uric acid (Pur) in relation to renal function (Ccr). Of the cases with Ccr greater than 50 ml/min (Ccr>50), 35% of male and 30% of female were revealed to be hyperuricemic, whereas in cases with Ccr less than 50 ml/min, Pur tended to rise while Pcr and BUN are still within normal range, consequently 97% of this group showed hyperuricemia. Thus an incidece of hyperuricemia is shown to be distinctly high in cases of chronic glomerulonephritis. Of all studied 203 cases, Pur was negatively correlated to Ccr, coefficient being -0.61. In the statistical calculation excluding hyperuricemic cases with Ccr>50, this negative correlation becomes more prominent (coefficient; -0.75), suggesting paradoxically that the cause of hyperuricemia of this group is other than a mere retention due to decreased GFR. In the cases with Ccr>50, uric acid excretion in the hyper-and the normouricemic was uniform, thus Cur/Ccr was significantly smaller in the former, than in the latter, showing that hyperuricemia will not accompany hyperuricosuria. Oral loading of Yeast RNA to 12 hyperuricemic patients with Ccr 50 revealed that this group is further devided into three subgroups in view of uric acid handling of the kidney ; a) further increase of Pur without increase of uric acid excretion in the urine, b) no increase of Pur with increased urinary uric acid excretion, and c) intermediate of a) and b). It is therefore suggested that hyperuricemia in chronic glomerulonephritisswith unimpaired renal function is produced by decreased tubular excretion or overproduction of uric acid. The direct relationship of the impaired tubular function to glomerulonephritis however remains to be confirmed.