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eGFR Calculator (CKD-EPI)

Estimate glomerular filtration rate with the CKD-EPI 2021 equation from creatinine, age and sex, with the chronic kidney disease stage.

Enter the values to see the result here.

Calculation aids only. They do not replace clinical judgement or the drug reference. Verify every dose before using it on a patient.

Formula

The CKD-EPI 2021 creatinine equation, with serum creatinine ScrS_{cr} in mg/dL and age in years:

eGFR=142×min⁡(Scrκ,1)α×max⁡(Scrκ,1)−1.200×0.9938age×1.012 [if female]\text{eGFR} = 142 \times \min\left(\frac{S_{cr}}{\kappa},1\right)^{\alpha} \times \max\left(\frac{S_{cr}}{\kappa},1\right)^{-1.200} \times 0.9938^{\text{age}} \times 1.012\ [\text{if female}]

with κ=0.7\kappa = 0.7 and α=−0.241\alpha = -0.241 for women, and κ=0.9\kappa = 0.9 and α=−0.302\alpha = -0.302 for men. Creatinine in µmol/L is divided by 88.4 first.

Worked example

A 50-year-old man has a creatinine of 1.0 mg/dL.

  • Scr/κ=1.0/0.9=1.111S_{cr}/\kappa = 1.0/0.9 = 1.111, so the minimum term is 1 and the maximum term is 1.111−1.2=0.8811.111^{-1.2} = 0.881.
  • Age term: 0.993850=0.7330.9938^{50} = 0.733.
  • eGFR =142×0.881×0.733=91.7= 142 \times 0.881 \times 0.733 = 91.7 mL/min/1.73 m², stage G1.

Repeat with a creatinine of 2.0 and the result falls to about 38, stage G3b.

Common mistakes

  • Entering creatinine in µmol/L while the unit is set to mg/dL. The result will look like kidney failure.
  • Using the equation for children, for acute kidney injury or when creatinine is changing quickly.
  • Reading a single value as a diagnosis. Chronic kidney disease needs three months of reduced function or markers of damage.
  • Dosing from eGFR when the drug label specifies Cockcroft-Gault clearance.

Frequently asked questions

Why does the 2021 equation have no race term?

The 2021 CKD-EPI refit, recommended by the US National Kidney Foundation and the American Society of Nephrology, removed the race coefficient because race is a social construct and was not a reliable proxy for kidney function. Use it for adults of every background.

Is eGFR the same as creatinine clearance?

No. eGFR is standardised to a body surface area of 1.73 m² and is used to stage kidney disease. Creatinine clearance (Cockcroft-Gault) estimates the actual mL/min a patient clears and is the traditional basis for drug dose adjustment. Check which your drug label uses.

When is eGFR unreliable?

In acute kidney injury where creatinine has not yet reached a steady state, in very high or low muscle mass, amputations, pregnancy, and in children under 18. Cystatin C or a measured GFR may be needed.

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