Methods of GFR determination--creatinine clearance after cimetidine administration in clinical practice.

Determination of clearance of endogenous creatinine using its plasma and urinary concentration (standard clearance) or Cockroft and Gault equation (estimated clearance) is commonly performed for assessment of glomerular filtration rate. Although evaluation of renal function in this way is useful, it is biased with an error resulting from secretion of creatinine in tubules. This error can be reduced by determining the clearance after administration of cimetidine. This study enrolled 40 patients who were divided into two groups--the first group consisted of 12 healthy subjects and the second group joined healthy subjects and patients with chronic renal failure. The second group was divided into three subgroups in relation to creatinine serum concentration (intervals: creatinine < 1 mg/dL - 9 subjects, creatinine 1-2 mg/dL - 7 subjects, creatinine > 2 mg/dL - 10 subjects). Estimated and standard creatinine clearance, clearance after cimetidine administration and inulin clearance were assessed. Analysis of mean percentage differences between clearance value after cimetidine administration and estimated or standard clearance shows increasing contribution of tubular creatinine secretion with increase in plasma creatinine concentration. This study suggests that determination of creatinine clearance after cimetidine administration can be used in precise evaluation of renal function.