- Serum creatinine < 220 μmol/L or estimated glomerular filtration rate > 40 ml/min/1.73m2 by the Nankivell formula, which had been validated in kidney transplant recipients; this equation was expressed for use with a standard serum creatinine assay: glomerular filtration rate = 6.7/(standardized serum creatinine in μmol/L / 1000) + weight (kg)/4 - urea (mmol/L)/2 - 100 / height2 (m) + 35 if the subject is male (or 25 if the subject is female)