| Methods | Equation | Remarks |
| Serum creatinine (Cr) | ___ | • Pitfalls in patients with low muscle mass and significant peripheral edema • Prone to drug disturbances (interference with tubular excretion of Cr & Cr assays) |
| 24-hr urine collection | (24-hr urine Cr ÷24-hr serum Cr ) x 0.7 | • Prone to error of collection • Cumber and not welcomed by patients |
| Plasma Cystatin C | ___ | • More sensitive than serum Cr to detect early renal dysfunction • Expensive and not widely available |
| CG equation | CrCl (mL/min) = [(140-Age) x lean BW (kg)] ÷ [Serum Cr (mg/dL) x 72] x 0.85 (if female) | • Convenient • Accurate in stable renal function • Can be problematic in changing clinical conditions and renal function |
| MDRD equation | GFR (mL/min/1.73m2) = 175 x(SCr)-1.154 x (Age)-0.203 x (0.742 if female) x (1.212 if African American) | • Accurate in moderate renal impairment • Can be imprecise in extremes of renal function |
| CKD-EPI equation | GFR = 141 x min (SCr/α 1) x max (SCr/K, 1)-1.209 x 0.993(Age) x 1.108 (if female) x 1.159 (if black) K=0.7 if female & 0.9 if male α = -0.392 if female & -0.411 if male Min – The minimum of SCr/K or 1 Max – The maximum of SCr/K or 1 SCr (mg/dL) | • Less bias than MDRD equation especially in patients with higher GFR • Not widely adopted in many laboratories |