1. What is the GFR Formula?

The Glomerular Filtration Rate (GFR) formula estimates kidney function by calculating the flow rate of filtered fluid through the kidneys. It's a key measure of renal function and helps in diagnosing and staging chronic kidney disease.

2. How Does the Calculator Work?

The calculator uses the GFR formula:

Where:

• \( age \) — Age in years
• \( weight \) — Body weight in kilograms
• \( creatinine \) — Serum creatinine in mg/dL
• 0.85 — Adjustment factor for female gender

Explanation: The formula accounts for age-related decline in kidney function, body size, and gender differences in muscle mass which affects creatinine production.

3. Importance of GFR Calculation

Details: GFR is the best overall measure of kidney function. It helps in detecting early kidney disease, monitoring disease progression, and adjusting drug dosages that are excreted by the kidneys.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between GFR and eGFR?
A: GFR is the actual measurement, while eGFR is an estimate calculated from formulas like this one. Direct GFR measurement requires specialized tests.

Q2: What are normal GFR values?
A: Normal GFR is about 90-120 mL/min. Values below 60 for 3+ months indicate chronic kidney disease.

Q3: Why is gender a factor in the calculation?
A: Women typically have less muscle mass than men, resulting in lower creatinine levels. The 0.85 factor adjusts for this difference.

Q4: Are there limitations to this formula?
A: This formula may be less accurate in very old, very young, obese, or severely malnourished individuals.

Q5: Should I fast before creatinine testing?
A: While not strictly necessary, avoiding meat for 24 hours before the test can provide more accurate results.