Estimated Glomerular Filtration Rate (eGFR)
August 9th, 2018
Overview
eGFR is the most common means for estimating glomerular filtration rate (GFR) in clinical practice in the context of assessing chronic kidney disease; equations rely on serum creatinine measurements and are adjusted depending on the patient's demographic information.
eGFR calculators can be found in the tools section of the app.
Stages of Chronic Kidney Disease
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Stage eGFR (ml/min/1.73 m²) I >90 I 60 - 89 III 30 - 59 IV 15 - 29 V <15
MDRD Formula
The MDRD formula was created for the modification of diet in renal disease (MDRD) study based on data from patients with advanced renal failure. This formula is commonly used by labs to calculate an eGFR to be reported along with the creatinine.
Formula
- eGFR = 186.3 × Creatinine-1.154 × Age-0.203 ( × 0.742 if female) ( × 1.212 if African origin)
There are also five-variable (including BUN) and six-variable (including albumin) MDRD formulae for eGFR.
Limitations
- Not validated for patients with normal renal function
- Not validated for acute kidney injury and for patients with rapidly changing renal function, as the data is from CKD
- Not accurate in pregnancy, severe malnutrition and in children
CKD-EPI Formula
Uses the same variables as the MDRD formula but with a slightly different equation that tends to be more predictive, especially at higher GFRs.
Formula
- eGFR = 141 × (Creatinine/X)Y × 0.993Age ( × 1.018 if female) ( × 1.159 if african origin)
Female:
Cr <0.7mg/dL (62μmol/L): X = 0.7; Y = -0.329
Cr >0.7mg/dL (62μmol/L): X = 0.7; Y = -1.209
Male:
Cr <0.9mg/dL (80μmol/L): X = 0.9; Y = -0.411
Cr >0.9mg/dL (80μmol/L): X = 0.9; Y = -1.209
Limitations
- Younger patients are more likely to have a higher eGFR and be classified in lower stages of CKD compared to other formulae
- Older patients (>80 years) are more likely to have a lower eGFR and be classified in higher stages of CKD compared to other formulae
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