The abbreviated MDRD equation
"eGFR" = 186.3("S"_text(Cr)/88.4) - (1.154×"Age"^"-0.203") × ("0.742 if female") × ("1.210 if African heritage")eGFR=186.3(SCr88.4)−(1.154×Age-0.203)×(0.742 if female)×(1.210 if African heritage)
The units of "S"_"Cr"SCr (serum creatinine) are ""mg/dL"mg/dL", and the units of "eGFR"eGFR are ""mL"//("min·1.73 m"^2)"mL/(min⋅1.73 m2)".
The "1.73 m"^21.73 m2 term normalizes the result to the accepted average adult body surface area.
The IDMS-traceable MDRD equation (more accurate)
A known amount of radioactively-labelled creatinine is injected into the patient, and the amount of serum creatinine is calculated from the isotope ratio as measured by GC-MS.
The formula is
"eGFR" = 175 × ("S"_"Cr")^"-1.154 "× "Age"^"-0.203" ×("0.742 if female") × ("1.212 if African heritage")eGFR=175×(SCr)-1.154 ×Age-0.203×(0.742 if female)×(1.212 if African heritage)
The CDK-EPI equation (most accurate)
"eGFR" = 141 × [min("S"_text(Cr)/κ,1)]^α × [max("S"_text(Cr)/κ,1)]^"-1.209" × 0.993^"Age" ×("1.018 if female") × ("1.159 if African heritage")
where
"S"_text(Cr) = serum creatinine in milligrams per decilitre
κ = 0.7 for females and 0.9 for males
α = -0.329 for females and -0.411 for males
"min"("S"_"Cr"/κ,1) = the minimum of "S"_text(Cr)/κ or 1
"max"("S"_"Cr"/κ,1) = the maximum of S_text(Cr)/κ or 1
If "S"_"Cr" is measured in micromoles per litre,
κ = 61.9 for females and 79.6 for males
