[Methods of assessment of the renal function in kidney transplant patients]

Glomerular filtration rate (GFR), which evaluates the evolution of the renal function, can be directly assessed by the measure of urinary or plasmatic clearance of a specific marker that ideally should be freely filtrated, without haemodynamic or toxic effects and easily dosed. Unfortunately, such a sensible marker of renal function variations does not yet exist. Particularly for GFRs in the range of 60ml/min estimation formulas generally over or under-estimate the true GFR, especially the Cockcroft formula that estimates creatinine clearance. Therefore, it is recommended to use validated markers for the measurement of the true GFR (inulin, iohexol, Cr EDTA...), in particular for the follow-up of cohorts and for studies using GFR as an outcome measure. For daily clinical practice, it is possible to use estimation formulas, preferably the 4-variables MDRD equation. However, to optimize the accuracy of GFR measures estimated from these formulas, it is first necessary to control the homogenous calibration of creatinine measurement devices.