Protein intake, type of protein, muscle mass needs to be taken in consideration while measuring and comparing GFR in the same individual. Though minor but diurnal variation can make a difference in accepting/rejecting a kidney donor. There is need to factor in all the parameters of “physiological milieu” in measuring of estimating GFR. Till the time we have an ideal biomarker, selection of biomarker and keeping the physiological state steady will prevent over/under estimation of GFR.