Graphic comparison of equations that estimate glomerular filtration rate

Abstract

The equations used to estimate the filtration rate Glomerular are the Cockcroft-Gault and MDRD. Recently has been published the CKD-EPI referred as a safer equation. This paper is a comparison of graphs of these equations obtained varying its parameters: Men and women, 20,40,60 and 80 and creatinine ranges that include three levels of glomerular filtration: high rates, 60 and 10 ml / min. CKD-EPI equation was accepted as the reference and used only white ethnicity examples. In resulting graphs could be observed: a) A double profile in the curve plotted with CKD-EPI, with inflection in the level of high filtration rates and with a variable morphology regarding sex and age. It is the main virtue of this equation to produce logical results to high levels of glomerular filtration. b) Cockroft-Gault equation showed underestimation to CKD-EPI at glomerular filtration rates above 70, 40 and 15 ml / min in women aged 40, 60 and 80, respectively. Also underestimated 60 and 80 years males above 60 and 20 ml / min filtration rates respectively. The equation overestimates all filtration levels below just mentioned (with a brief isoestimatión period). Therefore there shouldn´t been refered as usually occurs that Cockroft-Gault equation always overestimates at all GFR values. c) MDRD-IDMS underestimated in women of all ages and almost all glomerular filtration values. In men aged 20 and 40 years underestimated for all glomerular filtration values. Finally it is noted that at any age underestimated at 60 ml / min filtrates. d) At level of 10 ml / min of filtration rate, required to start renal replacement, the curves of Cockcroft-Gault and MDRD-4 overestimate glomerular filtration respect to the CKDEPI. e) Cockcroft-Gault and CKD-EPI equations reduce glomerular filtration rates in linear mode regard increasing age. This is correct. That does not happen the same way with the MDRD. The background to the development of CKD-EPI equation and the important cohort used by the authors to define it predisposes to employment this equation to estimate glomerular filtration rate from serum creatinine. The graphs presented here also adhere to it
showing marked CKD-EPI differences with the other equations.