One can estimate GFR
from age, sex, body weight, and serum
creatinine value of a person from the following formula (Cockcroft
Creatinine clearance in ml/min = (140 - Age in years) × (Body weight in kg)
(72 × Serum creatinine in mg/dl)
In females, the value obtained from above equation is multiplied by 0.85 to get the result.
It is recommended by National Kidney Foundation (USA)
to calculate creatinine clearance by Cockcroft
or other equation from serum creatinine value rather than estimating creatinine clearance from a 24-hour urine sample
. This is because the latter test
is inconvenient, time-consuming, and often inaccurate.