RELATIONSHIP BETWEEN PLASMA CREATININE CONCENTRATION AND GLOMERULAR-FILTRATION RATE IN DOGS

Glomerula filtration rate (GFR), plasma creatinine concentration (CR), and plasma urea nitrogen concentration (BUN) were measured in 129 adu lt dogs with reduced renal mass. A preliminary examination of the rela tionship between CR and GFR was conducted, and the inverse model (GFR vs. 1/CR) was chosen for further evaluation, The slope of the regressi on of GFR on 1/CR which was computed from actual data was not statisti cally different from a theoretical regression line generated from the clearance equation. Evaluation of subsets of the population revealed n o significant difference between male (n = 69) and female (n = 60) dog s on the slope of the regression equations. Diets differing in protein concentration (16% protein, n = 35: 21% protein, n = 75: 32% protein, n = 19) did not cause a significant difference in the slope of the re gression equations. The regression equation and the confidence interva ls generated in this study may be used to predict a probable range of GFR values from CR in individual dogs. Such values may be useful in ad justing drug dosages in dogs with renal disease. However, since the de rived equation did not differ significantly from the theoretical inver se relationship between GFR and CR, it remains to be established wheth er the equation is advantageous.