Creatinine clearance following cimetidine for estimation of glomerular filtration rate

Abstract

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.

Glomerular filtration rate measurement and estimation in chronic kidney disease

“…The protocol modified by Hellerstein and colleagues used cimetidine for 3 days at a dose of 20 mg/kg in two divided doses (maximum 1,600 mg per day and a sliding scale dose reduction for decreased GFR) [24]. After a final dose of half the daily dose and an oral load of 7-8 ml/kg of fluids, urine is collected for approximately 2 h under supervision [25].…”

“…Such a formula generally provides a good estimate of GFR (r~0.9) when compared with creatinine and inulin clearance data [24,26]. Interestingly, at high values of GFR, the variation between inulin clearance and GFR estimated by the Schwartz formula was about 20%, but it was much smaller at lower levels of GFR [24,26].…”

“…Such a formula generally provides a good estimate of GFR (r~0.9) when compared with creatinine and inulin clearance data [24,26]. Interestingly, at high values of GFR, the variation between inulin clearance and GFR estimated by the Schwartz formula was about 20%, but it was much smaller at lower levels of GFR [24,26]. It should be noted that these constants were generated from creatinine values measured using a modification of the Technicon autoanalyzer method, which relies on a Jaffe chromogen reaction to quantify creatinine.…”

Evaluation of Renal Function Estimation Formulas Specific to Dynamic Renal Function for Drug Dosing in Critically Ill Patients

“…The bias of Schwartz formula estimates compared to creatinine clearances is relatively small; however, the Schwartz formula has been shown to overestimate inulin clearance, particularly in children with low GFR. 168,169,172 Although formulas that estimate creatinine clearance overestimate GFR, they provide an estimate that is accurate enough for K/DOQI National Kidney Foundation Part 5. Evaluation most clinical purposes and represent a better alternative to assessing kidney function than serum creatinine alone.…”

“…127,[182][183][184][185][186] None of these studies demonstrated substantial improvement in estimating creatinine clearance using a 24-hour or timed urine collection over the use of either the Schwartz or CounahanBarratt prediction equations. One relatively small study 169 Important exceptions may be the estimation of GFR in individuals with variation in dietary intake (vegetarian diet, creatine supplements) or muscle mass (amputation, malnutrition, muscle wasting), since these factors are not specifically taken into account in prediction equations. In these situations, collection of a 24-hour urine sample for measurement of creatinine clearance, or measurement of clearance of an exogenous filtration marker, may provide better estimates of GFR than prediction equations.…”