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")#
The units of #"S"_"Cr"# (serum creatinine) are "#"mg/dL"#", and the units of #"eGFR"# are "#"mL"//("min·1.73 m"^2)"#".
The #"1.73 m"^2# 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")#
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
