Renal
Cockcroft-Gault
Estimates creatinine clearance from age, weight, sex, and serum creatinine. Used historically and still referenced by many regulatory drug-dosing guides (e.g., the FDA).
Use ideal or adjusted body weight if obese, per institutional convention
Source
Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron 1976.