# How can you calculate eGFR if you know the creatinine level?

Nov 21, 2016

You one of three equations to calculate $\text{eGFR}$.

#### Explanation:

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 $\text{S"_"Cr}$ (serum creatinine) are "$\text{mg/dL}$", and the units of $\text{eGFR}$ are "$\text{mL"//("min·1.73 m"^2)}$".

The ${\text{1.73 m}}^{2}$ 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

${\text{S}}_{\textrm{C r}}$ = 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 $\text{S"_"Cr}$ is measured in micromoles per litre,

κ = 61.9 for females and 79.6 for males