eGFR Calculator
Calculate your Glomerular Filtration Rate based on Serum Creatinine (CKD-EPI 2021 Formula)
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eGFR: — mL/min/1.73m²
Understanding Your Creatinine and eGFR Results
This calculator estimates your Glomerular Filtration Rate (GFR) using the 2021 CKD-EPI Creatinine Equation. This metric is the standard way medical professionals assess kidney function. Unlike older formulas, the 2021 equation does not include a race coefficient, providing a more equitable assessment for all patients.
What is Serum Creatinine?
Creatinine is a waste product generated by your muscles from the breakdown of a compound called creatine. Your kidneys serve as the filter for this waste, removing it from your blood and expelling it through urine. When kidney function declines, creatinine accumulates in the blood. Therefore, higher serum creatinine levels generally indicate lower kidney function, though this is adjusted for age and biological sex.
How to Interpret eGFR Results
Your eGFR number represents the flow rate of filtered fluid through the kidney. The results are typically categorized into stages of Chronic Kidney Disease (CKD):
| CKD Stage | eGFR Range (mL/min/1.73m²) | Description |
|---|---|---|
| Stage 1 | 90 or higher | Normal or high kidney function (requires other signs of damage for diagnosis) |
| Stage 2 | 60 – 89 | Mildly decreased kidney function |
| Stage 3a | 45 – 59 | Mild to moderately decreased kidney function |
| Stage 3b | 30 – 44 | Moderately to severely decreased kidney function |
| Stage 4 | 15 – 29 | Severely decreased kidney function |
| Stage 5 | Less than 15 | Kidney failure (End Stage Renal Disease) |
Factors Affecting Creatinine Levels
While eGFR is a robust indicator, "normal" creatinine levels can vary based on muscle mass. For example:
- Bodybuilders or muscular individuals may have naturally higher creatinine levels, potentially leading to an underestimated eGFR.
- Elderly individuals or those with low muscle mass may have lower creatinine levels, potentially leading to an overestimated eGFR.
- Diet (high protein intake) and certain medications can also temporarily affect creatinine levels.
When to See a Doctor
An eGFR below 60 mL/min/1.73m² for more than three months is a key indicator of Chronic Kidney Disease. However, acute changes in creatinine (AKI) require immediate attention. Always consult a nephrologist or primary care physician to interpret these results in the context of your full medical history.