NIH eGFR Calculator

NIH (NIDDK) CKD-EPI 2021 Equation:

\[ eGFR = 142 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.200} \times 0.9938^{age} \times (1.012 \text{ if female}) \]

Estimated GFR (eGFR):

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1. What is the NIH eGFR Calculator?

The NIH (NIDDK) eGFR Calculator uses the CKD-EPI 2021 equation to estimate glomerular filtration rate (GFR) from serum creatinine, age, and sex. This updated equation provides improved accuracy in assessing kidney function compared to previous versions.

2. How Does the Calculator Work?

The calculator uses the NIH CKD-EPI 2021 equation:

\[ eGFR = 142 \times \min(Scr/\kappa, 1)^\alpha \times \max(Scr/\kappa, 1)^{-1.200} \times 0.9938^{age} \times (1.012 \text{ if female}) \]

Where:

\( Scr \) — Serum creatinine (mg/dL)
\( \kappa \) — 0.7 (female) or 0.9 (male)
\( \alpha \) — -0.241 (female) or -0.302 (male)
\( age \) — Age in years
1.012 — Female multiplier

Explanation: This equation incorporates updated coefficients based on recent research to provide more accurate GFR estimates across diverse populations.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is essential for early detection of chronic kidney disease, monitoring disease progression, and guiding appropriate clinical management and treatment decisions.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. Ensure all values are valid (creatinine > 0, age between 1-120 years) for accurate results.

5. Frequently Asked Questions (FAQ)

Q1: What's new in the NIH CKD-EPI 2021 equation?
A: The 2021 version uses updated coefficients (142, -1.200, 0.9938) and gender-specific alpha values for improved accuracy across different population groups.

Q2: How does this differ from the original CKD-EPI equation?
A: The NIH 2021 version has refined coefficients based on more recent data and larger study populations, providing better performance in contemporary clinical settings.

Q3: What are the clinical applications of this calculator?
A: Used for CKD screening, staging, monitoring disease progression, and adjusting medication doses in patients with impaired kidney function.

Q4: Are there population limitations?
A: While validated across diverse populations, caution is advised in extremes of age, body composition, and certain ethnic groups not well-represented in validation studies.

Q5: When should confirmatory testing be considered?
A: When eGFR results are inconsistent with clinical presentation, or in patients where precise GFR measurement is critical for treatment decisions.