- Serum creatinine ≤1.5 x ULN, or measured creatinine clearance (CrCl) calculated by Cockcroft-Gault method ≥45 mL/min (confirmation of creatinine clearance is only required when creatinine is >1.5 x ULN) CrCl (glomerular filtration rate) = (140-age) x (weight/kg) x Fa (72 x serum creatinine mg/dL) where F = 0.85 for females and F = 1 for males.