Levey et al developed equations for estimating the glomerular filtration rate (GFR) from creatinine and urea clearances. The authors are from the Modification of Diet in Renal Disease (MDRD) Study Group.
Patient population: adults
Equation 4 (out of 7) - based on the average of the 2 clearances:
GFR in mL per min per 1.73 sq meter BSA =
= 1.11 * ((creatinine clearance in mL per min per 1.73 sq meter BSA) + (urea clearance in mL per min per 1.73 sq meter BSA)) / 2
where:
• The factor 1.11 seems inconsistent with the factors used in the other equations. The result for the GFR can be higher than the creatinine clearance, which differs from the other equations.
Equation 5 (out of 7):
GFR in mL per min per 1.73 sq meter BSA =
= 1.04 * ((creatinine clearance in mL per min per 1.73 sq meter BSA)^(0.751)) * ((urea clearance in mL per min per 1.73 sq meter BSA)^(0.226)) * (racial factor)
where:
• The racial factor is 1.109 if Black, else 1.0
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