[The effect of H2 receptor blockers on renal function. An attempt to accurately measure glomerular filtration]

Measurement of creatinine concentrations in serum and urine has for many years been a routine method for studying renal function in general and glomerular filtration in particular. Unfortunately, the method remains inaccurate due to partial excretion of creatinine by way of active tubular transport. Solutions are awaited to suppress tubular excretion and thus improve the reliability of creatinine clearance for the assessment of renal function. This work was designed to determine whether H2 receptor blockers are capable of suppressing tubular transport of creatinine. The study group consisted of 76 healthy individuals randomly assigned to groups which were placed on cimetidine, ranitidine or famotidine. Creatinine clearance was measured in all participants. Inulin clearance was determined only in participants receiving the full dose of cimetidine (3 x 200 mg + 400 mg after 12 h). It was found that the full cimetidine dose significantly reduced creatinine clearance from 109.46 to 75.62 mL/min. Correlation between inulin and creatinine clearances was stronger after the full dose, as well as in subjects with initially lower creatinine clearance values. Administration of a single 400 mg dose of cimetidine, ranitidine 300 mg or famotidine 40 mg produced an insignificant reduction in creatinine clearance. The present findings suggest that the full dose of cimetidine is capable of inhibiting tubular transport of creatinine and thus may improve the accuracy of creatinine clearance measurements for the study of renal function.