- Creatinine Estimated creatinine clearance as calculated using the modification of diet in renal disease (MDRD) equation must be greater than or equal to 60ml/min/1.73m^2. The formula to be used is MDRD: 186 times (Scr)(-1.154) times (Age)(0.203) times (0.742 if female) times (1.212 if African American)