Creatinine clearance following cimetidine for estimation of glomerular filtration rate
Simultaneous inulin (C in) and creatinine clearance (C Cr) studies were performed on 53 pediatric renal patients using a cimetidine protocol. Since cimetidine blocks the tubular secretion of creatinine, it was hypothesized that C Cr measured following cimetidine would closely approximate the C in. C in was compared with C Cr with the latter calculated from: (1) a 24-h urine collection, (2) plasma creatinine, height, and a proportionality constant, (3) the same plasma and urine specimens used for calculating C in, and (4) from the plasma and urine specimens of the four 30-min clearance periods treated as a single 2-h clearance. The C in was very closely approximated by the C Cr calculated from the same specimens used for the C in and by the 2-h clearance. The cimetidine protocol, with C Cr derived from a 2-h urine collection obtained under supervision in the office or clinic, provides a convenient and inexpensive procedure for estimation of glomerular filtration rate in a clinical setting.