Glossary term
Creatinine
Part of: Kidney Function Tests
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- Written in plain English
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- Reviewed by Medipher Editorial Team
A waste product from normal muscle activity that the kidneys filter out of your blood.
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Medipher explains medical wording in plain English — it does not diagnose or replace a clinician. If this is a medical emergency, call your local emergency number immediately.
Simple visual explanation
What is this?
Creatinine is a waste product made when muscles use energy. It's produced at a fairly steady rate and removed by the kidneys, which filter it out of the blood and into urine.
Because production is steady and removal is done by the kidneys, the level of creatinine in your blood is a helpful indirect measure of how well the kidneys are filtering.
Creatinine is included in almost every routine blood chemistry panel — often reported alongside urea and used to calculate eGFR.
Why is it important?
Creatinine is a core kidney marker. It's used to estimate the eGFR (an estimate of kidney filtration) and monitor kidney health over time.
Trends are usually more informative than a single number. A stable creatinine, even slightly outside the reference range, is often reassuring.
It also helps clinicians dose medications that depend on kidney function safely.
Where you'll see it: U&E (Urea & Electrolytes) blood test panels.
How doctors use this result
Clinicians may use this result to:
- Estimate kidney function via the eGFR calculation.
- Check kidney health before starting or adjusting certain medications.
- Detect changes in kidney function early, before symptoms appear.
- Monitor ongoing kidney conditions and response to treatment.
What's the normal range?
| Adult women | 50–90 µmol/L (roughly) |
| Adult men | 60–110 µmol/L (roughly) |
Muscle mass affects creatinine, so ranges vary between people. Use the range on your own report.
People with more muscle sit higher in the range; those with less muscle sit lower. A stable value that is slightly outside the range is often normal for you.
- Lower than the usual range
- Very low muscle mass or, occasionally, pregnancy.
- Within the usual range
- A result inside the range printed by the laboratory is generally read as usual for Creatinine at the time of the test.
- Higher than the usual range
- Reduced kidney function, dehydration, some medications, or high muscle mass.
Normal ranges are guides, not verdicts. Interpretation depends on your age, sex, symptoms, medical history, medications and other investigations — which is why your clinician looks at the whole picture rather than a single value.
Common reasons it may be high
Reduced kidney function
If the kidneys filter less blood, creatinine builds up in the circulation.
Dehydration
Less fluid in the blood concentrates creatinine and reduces filtration temporarily.
Some medications
Certain painkillers, antibiotics and blood-pressure drugs can raise creatinine, sometimes reversibly.
High muscle mass or high-protein diet
More muscle activity generates more creatinine at baseline.
Recent intense exercise
Vigorous exercise before the test can temporarily push creatinine higher.
Common reasons it may be low
Very low muscle mass
Less muscle produces less creatinine, which is often normal in older adults or after long illness.
Pregnancy
Increased blood volume dilutes creatinine and increases kidney filtration.
Does an abnormal result always mean something is wrong?
Not necessarily. A number that sits outside the printed range is a prompt for interpretation — not a diagnosis.
- A single result rarely gives the full picture — clinicians interpret it alongside your symptoms.
- Your medical history, medications and other blood tests all shape the meaning of one value.
- Small movements just outside the reference range are common and often not concerning.
- Repeat testing over time is frequently more useful than any single number.
What might happen next?
- A repeat test, often with hydration corrected first.
- Review of medications that can affect kidneys.
- Urine tests to check for protein or blood.
- Referral to a kidney specialist if the change is significant or ongoing.
One result rarely tells the whole story. Clinicians look at your symptoms, medical history, medications and other tests together — and a single value that sits slightly outside the reference range is often normal for you. Repeat testing over time is frequently more useful than any one number. Medipher helps you understand what a result means in plain English, but it cannot diagnose medical conditions or replace advice from a doctor, nurse or pharmacist.
When should I speak to a healthcare professional?
Speak with your GP or another healthcare professional if:
- You've been asked to repeat the test.
- You're experiencing new or worsening symptoms.
- Your clinician has flagged the result as needing follow-up.
- You don't understand your results or feel unsure what to do next.
If you have severe symptoms — chest pain, severe breathlessness, fainting, heavy bleeding or feel very unwell — seek urgent help. If this is a medical emergency, call your local emergency number immediately. Medipher is designed to help explain medical information and is not an emergency service.
Frequently asked questions
Related guides
Commonly confused with
These tests sound similar to Creatinine, but each answers a different question.
- eGFReGFR is calculated from creatinine, so the two always move in opposite directions.
- UreaUrea reflects hydration, diet and other factors more strongly, so it is read with creatinine, not instead of it.
- Urine ACRACR looks for protein leaking into urine, which is a different question from how well waste is being cleared.
Learning collections
Follow a guided pathway that puts Creatinine in context, step by step.
Still unsure what your result means?
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- unfamiliar medical terminology
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Sources
General patient information referenced when writing this page.
- NHS — Blood testsGeneral background
- NICE Clinical Knowledge SummariesGeneral background
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About this page
- Author
- Omer Suliman
- Medical reviewer
- Clinical review pending
Evidence. Written from public patient-information sources including the NHS, NICE and the Association for Laboratory Medicine, and reviewed for plain-English accuracy before publication.
Educational content only. Medipher explains medical language in plain English. It does not diagnose, and it is not a substitute for advice from a doctor, nurse or pharmacist. Read the medical disclaimer.
Nearly there — keep going.
A short summary and recommended next reads are just below.
Continue learning
- Next upeGFRAn estimate of how well your kidneys are filtering blood, calculated from your creatinine.
- Next upUreaA waste product formed when your body breaks down protein. The kidneys filter it out of your blood.
- Next upAbnormal (on a test report)A flag meaning a result differs from what the laboratory or test expected — not a statement about your health.
This glossary entry is general health information, not medical advice. Medipher explains medical wording in plain English and does not diagnose, provide treatment advice, or replace a GP, doctor, nurse or pharmacist. Always discuss your results with a qualified clinician.