Clinical use of estimating glomerular filtration rate equ-ations during pregnancy

Abstract

Background: Kidney disease, even when mild, was once considered so major an impediment to successful pregnancy and so dangerous to the mother’s wellbeing. High-risk pregnancy mainly associated to renal impairment may occur in 10-20% of gestations and it is very important that renal function is closely monitored to prevent or minimize maternal and fetal complications. This study was designed to investigate the performance of Cockcroft-Gault CGeq and the simplified MDRDeq equations in healthy pregnant women to assess renal function. Methods: We studied 167 normal ambulatory pregnant women and kidney function was contemporaneously estimated through the CGeq and the simplified MDRDeq and calculated through the creatinine clearance (Ccr). Serum and urinary creatinine were assayed using Jaffé reaction method in the same AutoAnalyser. Results: When we compared calculated and estimated clearences for measurement of kidney function we observed that CGeq overestimated renal function (CGeq = 168.41 ± 38.80 ml/ min/1.73 m2, Ccr = 146.27 ± 30.49 ml/min / 1.73 m2, p < 0.001), MDRDeq underestimated renal function (Ccr = 146.27 ± 30.49 ml/min / 1.73 m2, MDRDeq = 129.15 ± 29.28 ml/min / 1.73m2, p < 0.001). Conclusions: Our results demonstrated that CGeq overestimated, MDRDeq underestimated significantly kidney function during gestation in healthy women and cannot be recommended to assess renal function in obstetric practice. Ccr remains a useful clinical tool in pregnant women until the development of a specific equation that considers the several important maternal renal physiological alterations and provides the measure of GFR the most unbiased and precise as possible.