eGFR Calculator UK NHS Calculator

UK NHS eGFR 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 UK NHS eGFR Equation?

The UK NHS (National Health Service) eGFR equation estimates glomerular filtration rate (GFR) from serum creatinine, age, and sex. This equation is specifically adapted for use in the UK healthcare system and provides accurate assessment of kidney function for the UK population.

2. How Does the Calculator Work?

The calculator uses the UK NHS eGFR 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: The equation accounts for non-linear relationship between creatinine and GFR, with different coefficients optimized for the UK population.

3. Importance of eGFR Calculation

Details: Accurate GFR estimation is crucial for diagnosing chronic kidney disease, determining disease stage, and guiding medication dosing in the UK healthcare system.

4. Using the Calculator

Tips: Enter serum creatinine in mg/dL, age in years, and select gender. All values must be valid (creatinine > 0, age between 1-120).

5. Frequently Asked Questions (FAQ)

Q1: Why use the UK NHS equation instead of CKD-EPI?
A: The UK NHS equation is specifically calibrated for the UK population and is the standard used within the National Health Service for eGFR reporting.

Q2: What are normal eGFR values for UK adults?
A: Normal is generally ≥90 mL/min/1.73m², though values decline with age. Below 60 for 3+ months indicates CKD according to NICE guidelines.

Q3: When should creatinine be measured in the UK?
A: Following UK guidelines, morning samples are preferred. Testing should be done when clinically indicated for kidney function assessment.

Q4: Are there limitations to this equation in the UK?
A: As with all estimating equations, it may be less accurate in extremes of age, amputees, pregnant women, and those with rapidly changing kidney function.

Q5: Is this equation used for drug dosing in the UK?
A: For precise drug dosing, measured GFR may be needed in certain populations, though eGFR is commonly used for initial dosing guidance.