The eGFR Calculator estimates glomerular filtration rate (GFR) using serum creatinine, age, sex, and race. It helps diagnose and monitor chronic kidney disease (CKD) with two validated equations:
CKD-EPI: Newer, more accurate for early CKD detection.
MDRD: Older, less precise for near-normal function.
Formulas
1. MDRD Equation
eGFR (mL/min/1.73m²) =
175 × (SCr/88.4)-1.154 × Age-0.203
× (0.742 if female)
× (1.212 if Black)
Variables:
- SCr: Serum creatinine (µmol/L or mg/dL).
- Age: Years.
- Sex: Female multiplier = 0.742.
- Race: Black multiplier = 1.212.
2. CKD-EPI Equation (More Accurate):
eGFR = 141 ×
(
min
SCr
κ
, 1
)
α ×
(
max
SCr
κ
, 1
)
−1.209 ×
0.993Age
×
(1.018if female)
×
(1.159if Black)
Where:
- κ: 61.9 (females) or 79.6 (males) for SCr in µmol/L; 0.7 (females) or 0.9 (males) for SCr in mg/dL.
- α: -0.329 (females) or -0.411 (males).
🧮 eGFR Calculator (MDRD & CKD-EPI)
How to Use the Calculator
- Input:
- Serum creatinine (SCr) in mg/dL or µmol/L.
- Age (years).
- Sex (male/female).
- Race (Black/non-Black).
- Select Formula: MDRD or CKD-EPI.
- Calculate eGFR.
CKD Staging (KDIGO Guidelines)
| eGFR (mL/min/1.73m²) | Stage | Interpretation |
|---|---|---|
| ≥90 | G1 | Normal kidney function |
| 60–89 | G2 | Mildly decreased |
| 45–59 | G3a | Mild-moderate CKD |
| 30–44 | G3b | Moderate-severe CKD |
| 15–29 | G4 | Severe CKD |
| <15 | G5 | Kidney failure (dialysis needed) |
Key Notes
- CKD-EPI vs. MDRD:
- CKD-EPI is more accurate for eGFR >60 mL/min.
- MDRD may underestimate eGFR in healthy individuals.
- Limitations:
- Not valid for acute kidney injury (AKI).
- Less accurate in extremes of age/muscle mass (e.g., elderly, amputees).
- Critical Thresholds:
- eGFR <60 for ≥3 months = CKD.
- eGFR <15 = Kidney failure.
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