Calculating GFR With One Kidney

CKD-EPI Equation for GFR Estimation:

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

Estimated GFR (eGFR):

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1. What Is GFR With One Kidney?

This calculator estimates glomerular filtration rate (GFR) using a modified CKD-EPI equation specifically designed for individuals with one kidney. The equation accounts for the physiological changes in renal function assessment for single-kidney patients.

2. How Does The Calculator Work?

The calculator uses the modified CKD-EPI 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 modified equation provides accurate GFR estimation for individuals with single kidney function, accounting for compensatory hypertrophy and functional adaptation.

3. Importance Of GFR Estimation

Details: Accurate GFR assessment is crucial for monitoring kidney function in individuals with one kidney, whether due to donation, surgical removal, or congenital absence. It helps in early detection of renal impairment and guides clinical management.

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). The calculator provides estimated GFR adjusted for single kidney physiology.

5. Frequently Asked Questions (FAQ)

Q1: Why Use A Modified Equation For Single Kidney?
A: Standard equations assume two kidneys. This modified version accounts for compensatory changes and provides more accurate estimates for single-kidney patients.

Q2: What Is Normal GFR With One Kidney?
A: A healthy single kidney typically maintains 70-80% of normal two-kidney function. Values around 60-80 mL/min/1.73m² are often considered normal for single-kidney individuals.

Q3: How Often Should GFR Be Monitored?
A: Regular monitoring (annually or semi-annually) is recommended for individuals with one kidney to detect any decline in function early.

Q4: Are There Limitations To This Equation?
A: As with all estimation equations, it may be less accurate in extremes of age, body composition, or in patients with rapidly changing renal function.

Q5: Can This Be Used For Kidney Donors?
A: Yes, this calculator is particularly useful for monitoring kidney donors post-donation to ensure their remaining kidney maintains adequate function.