Renal Hemodynamics and Limitations of Creatinine Clearance in Determining Filtration Rate in Glomerular Disease

Abstract

A series of 160 Inulin/PAH clearances in 126 subjects was performed with the main emphasis on glomerular disorders. In 90 observations (67 subjects) simultaneous creatinine clearances were available. Earlier findings of the occurrence of high and supernormal C_PAH in some cases of glomerulonephritis have been supported and extended to systemic lupus erythematosus. Low filtration fractions in various types and stages of glomerulonephritis and systemic lupus erythematosus even at rather advanced renal impairment were observed and contrasted against the findings in cryptogenetic (essential) hypertension. High C_Cr/C_In ratios have been observed not only in cases of advanced renal insufficiency but also in glomerular disorders in subjects with a mild or moderate reduction in Cm and a maintained or high C_PAH at serum creatinine levels from 0.7 to 1.5 mg per 100 ml. Here, C_Cr/C_In ratios may be as high as 2.0 to close to 4. In some glomerular disorders, notably S.L.E., membranous glomerulonephritis, and transplant glomerulopathy, a normal or slightly elevated serum creatinine may occur at C_In levels below 40 or even 20 ml/min. Serum creatinine and C_Cr may fail to register even marked decreases in Cm with a maintained C_PAH as documented by a serially studied subject with systemic lupus.