The short answer
Creatinine is a normal waste product made when muscles are used. The kidneys filter it out of the blood. A creatinine blood test helps check kidney health. A high level can point to a kidney problem, but dehydration, hard exercise and diet can also raise it.
Creatinine is a normal waste product made by your muscles.
Healthy kidneys filter it out of your blood.
The test helps check kidney health and follow known kidney problems.
High levels do not always mean kidney disease. Dehydration, hard exercise and a diet high in meat can raise it.
On this page
Choose how you want to read this
The whole article, with every detail and caution.
The short version
Creatinine is a normal waste product. Your body makes it when you use your muscles. Your kidneys filter it out of your blood. A creatinine blood test helps check how well your kidneys are working.
What the test is used for
MedlinePlus says the test is used to:
- Check the health of your kidneys.
- Help diagnose kidney disease.
- Follow known kidney problems and see how treatment is working.
Why one number is not the whole story
A high creatinine can point to kidney disease or injury. But it is not always a kidney problem. MedlinePlus lists other causes, such as:
- Dehydration (not enough fluid in the body).
- Muscle injuries or muscle disorders.
- Intense exercise.
- A diet high in meat.
Low creatinine is less common. It may point to malnutrition or a condition that makes muscles smaller.
What is normal for you
What counts as normal depends on how much muscle you have, what you eat, your age and how active you are. Each lab sets its own normal range, shown on your report. Creatinine is often used to work out your eGFR, an estimate of how well your kidneys filter blood.
What to ask
Ask why your creatinine is being checked. Ask how it compares with your earlier results, and whether something like dehydration could explain a change. Your kidney result only makes sense next to your history, so your care team is the right judge.
Sources
Common questions
Does a high creatinine mean my kidneys are failing?
Not by itself. MedlinePlus notes that high creatinine can mean kidney disease or injury, but it can also come from dehydration, muscle injuries, intense exercise or a diet high in meat. Your care team reads it with other results.
Why is creatinine checked during cancer care?
Creatinine is a common way to check kidney health. Ask your care team why they are checking yours and how often.
What is the link between creatinine and eGFR?
MedlinePlus explains that eGFR is usually worked out from your creatinine result plus facts such as age and sex. eGFR gives an estimate of how well your kidneys filter blood.
What does a low creatinine mean?
Low creatinine is less common. MedlinePlus says it may point to malnutrition or a condition that makes muscles smaller.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
Tap a question to save it to your list (kept on this device).
Your next step
Plain-language definitions for the words on your report.
Talk with a trained specialist or navigator
Cancer Explained provides educational guidance, but does not replace trained specialists, social workers, or your medical team.
Talk to a trained cancer information specialist
Free, confidential assistance from NCI Cancer Information Service via phone, chat, or email.
Contact your oncology team
Locate after-hours contact numbers, portal messages, or urgent triage phone lines.
Find a patient navigator
Get one-on-one help with appointments, logistics, translation, and care coordination.
Find a genetic counselor
Discuss inherited mutation risk, family history, and genetic testing options.
Find an oncology social worker
Access emotional counseling, family support groups, and mental health resources.
Find a financial navigator
Locate copay assistance foundations, grant programs, and lodging/travel support.
Find a clinical-trial specialist
Search matching studies and speak with NCI trial information specialists.
Get urgent help
Fever of 100.4°F (38°C) or higher during chemo, severe pain, or trouble breathing: call your cancer care team right away, day or night. Call 911 for an emergency.
Know someone who needs this?
Plenty of people are looking for something like this and do not know where to start. If this would help a friend or someone you love, send it on — we have written an opening line so you do not have to stare at an empty message. You can change every word of it.
Your message is written and sent in your own email or messaging app — we never see who you send it to, and nothing is added to any list.
Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Sources last checked: 2026-10-02 what this meansLast updated: 2026-09-27Next planned review: 2027-09-27
Review details and limits
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status — Source checked. This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
General education — varies by person. Answers genuinely differ between people. This page explains what commonly varies and points you to your care team for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
Words to know
Tap any term to see what it means.
How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
Read more about our editorial process, our use of AI, and our corrections policy.
Spotted a problem? Report an error — a factual mistake, broken or outdated source, confusing wording, or anything that seems unsafe. Please do not include names, medical record numbers, dates of birth, addresses, or other identifying medical information in your report.
After using this page, do you understand what to do next?
Anonymous — we only record the answer, never who gave it.