Estimation of Glomerular Filtration Rate in Kidney Transplant Recipients Using Different Equations: A Controversial Issue

Although serum Cr has traditionally been used as the preferred marker of kidney function in the follow-up of renal transplant patients, it suffers several problems rendering its use inadvisable. Criterion standard measurements of GFR using an exogenous agent allow very precise kidney function estimation; but they are cumbersome, expensive, and time consuming, and not all centers have them available.Creatinine-derived equations allow us to easily estimate GFR better than unmodified serum Cr and CrCl, with a high grade of correlation with criterion standard methods. Although the global predictive performance of equations is not high in the renal transplant population, the observed accuracy can be considered acceptable for clinical trials or in epidemiology, where the random error can be compensated for by larger patient numbers and the systematic error can be distributed equally over the different patient groups .