What is eGFR?
eGFR is a calculated estimate of how well the kidneys filter waste from the blood. It uses creatinine and personal characteristics, so it remains an approximation. This is why trends and overall context (such as hydration and muscle mass) are important.
Why is eGFR relevant?
eGFR is a calculated estimate of how quickly your kidneys filter waste from the blood. It is currently the most commonly used marker for tracking kidney function at a glance, because it is more straightforward than creatinine alone. For people with risk factors for kidney load (diabetes, high blood pressure, long-term medication), eGFR is one of the markers worth tracking systematically.
How to read eGFR in context
eGFR is an estimate — not a direct measurement — and is affected by the same factors as creatinine (muscle mass, hydration, recent training). Always read it together with creatinine and look at the trend across several measurements; a single low value right after heavy effort is rarely conclusive. With a persistent decline, more in-depth kidney diagnostics almost always follows.