What is Calculated eGFR in Blood Test

Calculated eGFR Equation:

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

Calculated eGFR:

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1. What is Calculated eGFR in Blood Test?

Calculated eGFR (estimated Glomerular Filtration Rate) is a measure of kidney function calculated from serum creatinine levels, age, and gender. It provides an estimate of how well the kidneys are filtering waste from the blood.

2. How Does the Calculator Work?

The calculator uses the eGFR calculation 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 accounts for the non-linear relationship between serum creatinine and kidney filtration rate, with adjustments for age and gender differences in muscle mass and creatinine production.

3. Importance of Calculated eGFR

Details: Calculated eGFR is essential for assessing kidney function, detecting early kidney disease, monitoring kidney health over time, and guiding medication dosing decisions for drugs cleared by the kidneys.

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 is a normal eGFR range?
A: Normal eGFR is generally 90 mL/min/1.73m² or higher. Values below 60 for three months or more may indicate chronic kidney disease.

Q2: Why does age affect eGFR calculation?
A: Kidney function naturally declines with age, so the equation includes an age adjustment factor to account for this physiological change.

Q3: How often should eGFR be calculated?
A: For routine monitoring, annually is typical. More frequent testing may be needed for people with kidney disease, diabetes, or hypertension.

Q4: Are there limitations to this calculation?
A: This calculation may be less accurate in elderly individuals, people with extreme muscle mass, amputees, or those with rapidly changing kidney function.

Q5: Can eGFR be used for medication adjustments?
A: Yes, many medications require dosage adjustments based on eGFR levels, particularly antibiotics, diabetes medications, and pain relievers.