Creatinine and glomerular filtration rate: evolution of an accommodation

Abstract

This brief review examines the history of the use of creatinine as a measure of renal function. While there are more accurate markers of glomerular filtration, creatinine was chosen for convenience. Since the relationship of creatinine to glomerular filtration depends upon a tenuous balance of counterbalancing factors, practitioners should be alert to situations that alter that balance. While the averaging of variations over time helps to avoid some of the problems with diurnal variations in the past, the present-day reliance upon equations based upon a solitary serum value is likely to amplify those problems in clinical situations when the effect of disease, medications, diet and time of day upon that balance are not considered.

Evaluation of carboplatin dosage based on 4-variable modification of diet in renal disease equation

“…First, these patients have the lowest serum creatinine levels and recent publications highlight the lack of agreement between creatinine methods, due to lack of standarisation, and variable interference from other chromogens [2,6,9,10] which is particularly significant at lower creatinine levels. Ando et al [11] derived and validated a correction to the Cockroft-Gault formula when using the enzymatic creatinine method.…”

“…Some practitioners cap the carboplatin dose to allow for this, but others appear unaware of this practice. Many authors have highlighted the inaccuracies of substituting GFR derived from any of these formulae [2,6,8], particularly in patients with normal renal function. The variation of correlation coefficients in the various studies probably reflects the number of patients in the study with normal renal function, as all equations deviate significantly from the true GFR for these patients.…”

“…However, there are difficulties in consistently providing an accurate 24-h urine collection. This led to the introduction of a variety of calculations to estimate CrCl based on serum creatinine alone [2] the most popular of which have been the Cockcroft-Gault [3] and the Jelliffe formulae [4] (Appendix). It is the routine practice in our institution to incorporate the CockcroftGault and the Jelliffe equations in calculating the carboplatin dose using the Calvert formula.…”

The Comparative Benefits of the Fractional Excretion of Urea and Sodium in Various Azotemic Oliguric States

“…Since the FeNa was originally designed only for oliguric patients [1], and since urea reabsorption is urine flow dependent [24,25], only oliguric patients were included. All patients with drugs or disease states that have previously reported to interfere with either (1) creatinine secretion or (2) the Jaffe reaction and produce either a falsely elevated or depressed serum creatinine [26,27] were excluded. Similarly all patients with diseases associated with spurious sodium concentration analysis performed by ion selective electrodes such as thrombocythemia, hyperlipidemia or hyperproteinemia [28] were excluded.…”

A review of eGFR reporting after 6 months in practice

“…Problems with the interpretation of serum creatinine results arise from analytical methods, interindividual variability in results due to differences in muscle mass, and the fact that the renal excretion of creatinine varies with deterioration in renal function 1. There has therefore been a search for a formula to relate serum creatinine concentration to glomerular filtration rate (GFR) in a way that creates discrete decision values for the categorisation of chronic kidney disease (CKD) 2.…”