The use of body surface area for determination of age, body weight, urine creatinine, plasma creatinine, serum creatinine, urine volume, and creatinine clearance: the reliable canonical method of assessing renotoxicity in animals

A preponderance of drugs and xenobiotics are toxic to kidneys. Renal impairment can be assessed using creatinine clearance. However, because of the principle of reduction, refinement, and replacement (3R), new formulas have been derived from the human creatinine clearance formulas \( \left({C}_r{C}_l=\frac{K\times \left(140- age\right)\times W}{S_{cr}\times 72}\right)\ and\ \left({C}_r{C}_l=\frac{D\times \frac{nBS}{n}}{BS}\right) \). The newly developed formulas are \( \left({C}_r{C}_l=\frac{K\times \left(140- age\right)\times W}{D\times {S}_{cr}\times 72}\right)\ and\left({C}_r{C}_l=\frac{Ucr}{Pcr} \times 144\right) \) whereas K is constant (male = 1; female = 0.85), W (Weight), Scr (serum creatinine) and D (depuration) = \( \frac{\mathrm{Ucr}}{\mathrm{Pcr}} \), respectively. Also, Ucr (urine creatinine) and Pcr (plasma creatinine) must be considered for proper correlation of the estimated parameters. Body surface (BS) = BW^0.528 × H^0.528 × 0.14, whereas BW (body weight), H (height), K (0.14 for dog and human), and the exponent (0.528) have correlated very well for estimation of the parameters in dog and human. The units of creatinine clearance (CrCl = mL/min), serum creatinine (mg/dL), and plasma creatinine (mg/dL) must be considered integral parts of the formula. Time factor (60 × 24 = 1440 min) should be applied for parameters measured per minute. The findings revealed that creatinine clearance is physiologically, pharmacologically, and toxicologically related to body weight, body surface, age, clearance, and volume of urine creatinine, plasma creatinine, serum creatinine, urine volume, and height of mammals.