- Inadequate renal function defined as measured creatinine clearance less than 50 mL/min/1.73 m^2 based on the Cockcroft-Gault formula (adults) or Schwartz formula (age less than or equal to 12 years). Adults: estimated creatinine clearance rate (eCCr) (mL/min/) = (140 - age) x mass (kg) x (0.85 if female)/72 x serum creatinine (mg/dL; Creatinine clearance (mL/min/1.73m^2) = eCCr x 1.73/Body Surface Area (BSA) (m^2); Children: eCCr (mL/min/1.73 m^2) = k x height (cm) / serum creatinine (mg/dL) k = 0.33 (pre-term), 0.45 (full term to 1 year old), 0.55 (age 1-12 years).