Estimated GFR or eGFR For Staging Chronic Renal Disease.

A 62-year-old man with chronic kidney disease secondary to diabetes mellitus is reviewed. When assessing his estimated glomerular filtration rate (eGFR), which one of the following variables is not required by the Modification of Diet in Renal Disease (MDRD) equation?
A. Age
B. Serum creatinine
C. Ethnicity
D. Gender
E. Serum urea

Answer:
E. Serum urea

Discussion:
eGFR variables - Menomic CAGE - Creatinine, Age, Gender, Ethnicity.

estimated GFR or eGFR
Serum creatinine may not provide an accurate estimate of renal function due to differences in muscle. For this reason formulas were develop to help estimate the glomerular filtration rate (estimated GFR or eGFR). The most commonly used formula is the Modification of Diet in Renal Disease (MDRD) equation, which uses the following variables:
 serum creatinine
 age
 gender
 ethnicity

Factors which may affect the result are:
 pregnancy
 muscle mass (e.g. amputees, body-builders)
 eating red meat 12 hours prior to the sample being taken.

Chronic Kidney Disease  may be classified according to GFR:

Stage 1: GFR Greater than 90 ml/min, with some sign of kidney damage on other tests (if all the kidney tests* are normal, there is no CKD)
Stage 2: GFR 60-90 ml/min with some sign of kidney damage (if kidney tests* are normal, there is no CKD)
Stage 3a: GFR 45-59 ml/min, a moderate reduction in kidney function.
Stage 3b: GFR 30-44 ml/min, a moderate reduction in kidney function
Stage 4: GFR 15-29 ml/min, a severe reduction in kidney function
Stage 5: GFR Less than 15 ml/min, established kidney failure - dialysis or a kidney transplant may be needed