Good to knowOne result rarely tells the whole story. Your provider looks at your results together with your symptoms, exam, and other tests.
What the test is
Combined creatinine-cystatin C eGFR is often the most accurate estimate.
Why it's done
- Confirming a borderline eGFR
- Very high or low muscle mass
- Medicine dosing decisions
Getting ready and what happens
- No special preparation is needed.
How the test is done
- A health worker cleans the skin, puts a band around your arm, and draws blood from a vein with a small needle. It takes a few minutes.
What the results mean
High
Suggests reduced kidney function. Thyroid problems and high-dose steroids can also affect it.
Questions to ask your provider
- What do my results mean for me?
- Do I need to repeat this test or have other tests?
Risks
A blood draw is very safe. You may have slight pain or a small bruise where the needle went in.
Related conditions
Related tests
Sources
Last updated 2026-11-13.