Prediction of Creatinine clearance by several methods in patients with severe infections

Summary

Since almost all urinary creatinine is derived from the muscle mass, the amount of creatinine in the urine will be proportional to muscle mass, and it will show an almost constant decrease with age.

A simple equation for estimating creatinine clearance has been derived. For women the creatinine clearance (ml·min⁻¹) was [150−(years)]·body weight (kg)/serum creatinine (μmol·l⁻¹). For men <70 years it was [170−age (years)]·body weight (kg)/serum creatinine (μmol/l) and for men ≥70 years it was [160 — age (years)]·body weight (kg)/serum creatinine (μmol/l).

The prediction was quite simple when laboratory results were given in SI units. A simple nomogram was devised for easy estimation of the creatinine clearance in individual patients according to the age, sex and weight.

Predicted values according to our equations were compared with those derived from other formulae in 54 patients with severe infections treated with aminoglycosides. No major differences were found, but the new method seemed more convenient.