A serum creatinine test measures creatinine, a waste product from normal muscle activity, in your blood. Healthy kidneys filter it out, so a high level can mean the kidneys are not working well. Normal creatinine is about 0.7–1.3 mg/dL for men and 0.6–1.1 mg/dL for women. It is used to calculate eGFR.
What does the creatinine test measure?
Your muscles produce creatinine at a fairly steady rate every day, and your kidneys clear it into the urine. Because production is steady, the blood level mainly depends on how well the kidneys filter. If filtration drops, creatinine rises.
On its own, a creatinine number can mislead, because it also depends on how much muscle you have:
- Muscular people, gym-goers and athletes often have slightly higher creatinine with perfectly healthy kidneys.
- Creatine supplements and very high-protein diets (including a large meat meal the day before) can push creatinine up temporarily.
- Older adults, women and people with low muscle mass can have “normal-looking” creatinine even when kidney function has started to fall.
That is why labs convert creatinine into an eGFR (estimated glomerular filtration rate) using your age and sex; current guidelines use the CKD-EPI 2021 equation. eGFR estimates how many millilitres of blood your kidneys filter per minute and is what doctors use to stage kidney disease.
Creatinine is also checked before CT scans with contrast dye, and before and during treatment with certain medicines cleared by the kidneys.
Creatinine normal range
Where does your result fall?
Enter your Serum creatinine value from your report. Muscle mass, exercise and diet affect creatinine; check your eGFR too.
A general guide, not a diagnosis. The reference range on your own report takes priority, and a doctor should interpret any result outside it.
Ranges vary between labs and methods. Always compare your result with the reference range printed on your own report.
What abnormal results can mean
- High creatinine: Can suggest reduced kidney function, from long-standing diabetes or high blood pressure, kidney infection, stones blocking urine flow, or certain medicines. Dehydration, intense exercise, creatine supplements and high meat intake can cause temporary rises.
- Low creatinine: Usually reflects low muscle mass and is rarely a concern.
A single raised value is usually repeated. A rise over time matters more than one reading. Discuss your results with a doctor.
Who should get this test?
- People with diabetes or high blood pressure, at least yearly.
- People taking regular painkillers (NSAIDs), some BP medicines, or other kidney-cleared medicines.
- People using creatine or protein supplements who want a baseline (tell the lab you take them).
- Before a contrast CT scan, if requested.
- Anyone with swelling of the feet, reduced urine or foamy urine.
- Preparation: No fasting needed. Avoid heavy exercise for 24 hours and a large meat meal the night before.
This page is for general information and is not a substitute for medical advice. Always interpret your results with a qualified doctor.