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Creatinine

A waste product of normal muscle metabolism that the kidneys filter out at a fairly steady rate. Because production depends on muscle mass, the same creatinine means different things in a large young man and a small older woman — which is exactly why eGFR exists.

General information only — not a diagnosis, not treatment and not a substitute for your doctor. Reference ranges differ between laboratories, so the range printed on your own report is the one that counts, and only a clinician who knows your history can say what a result means for you. Never start, stop or change a medicine or supplement based on this page.

Usual adult reference range

The ranges below are typical adult reference intervals. Your own laboratory sets its own, printed next to your result, and that is the one to compare against.

Source: Typical adult reference interval published by clinical laboratories; sex-specific and method-dependent. · checked 2026-09-02

What a high result generally indicates

A raised creatinine usually means reduced kidney filtration, but dehydration, a very high meat intake, intense exercise and a large muscle mass all raise it without kidney disease. Some medicines raise it by blocking its secretion without changing filtration at all. A single high value is normally repeated.

What a low result generally indicates

A low creatinine usually reflects low muscle mass — older age, prolonged illness, limb loss — or pregnancy, which increases filtration. It is rarely a problem in itself, but it does mean eGFR may overestimate kidney function.

These are general patterns, not a diagnosis. Many things cause a high or low result, and the same figure means different things in different people. What yours means is a question for the doctor who ordered the test.

What affects this result

• Muscle mass — the largest non-kidney influence.
• A large meat meal in the hours before the test.
• Creatine supplements raise it.
• Dehydration raises it; pregnancy lowers it.
• Trimethoprim and cimetidine raise it without changing filtration.
• Intense exercise in the previous day or two.

Before the test

No fasting needed. Laboratories sometimes ask you to avoid a large meat meal beforehand.

Any preparation instruction that comes with your test slip overrides this general note — follow the one your clinician or laboratory gave you.

The one thing to take from this page

The range above is a typical interval for orientation. Your own laboratory's range, printed beside your result, is the one that applies to you — and a result is only meaningful alongside your symptoms, your history, your medicines and your other tests. That reading is a clinician's job. This page cannot diagnose anything, cannot tell you to change a medicine or a supplement, and is not a substitute for the person who ordered your test.

Frequently asked questions

Other markers

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