Creatinine test: normal range, high levels and what your result means

Creatinine is the simplest everyday check on how well your kidneys are filtering. Here's how to read your number, what can push it up, and when it needs a doctor.

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Quick answer

What is a normal creatinine level?

A normal serum creatinine is roughly 0.7 to 1.3 mg/dL (62 to 115 µmol/L) for adult men and 0.6 to 1.1 mg/dL (53 to 97 µmol/L) for adult women, though each lab prints its own range. Creatinine is a waste product your kidneys filter out, so a higher number can mean they're filtering less. Doctors read it with your eGFR.

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Health information, not medical advice. Your doctor knows your full picture; ask them about your result.

Range chart

Creatinine normal range chart

Typical serum (blood) creatinine reference ranges. Your lab's range on the report is the one to compare with.

Whomg/dLµmol/LNotes
Adult men0.7 to 1.362 to 115More muscle means a little more creatinine, so men run higher.
Adult women0.6 to 1.153 to 97Usually lower than men. Pregnancy lowers it further.
Teenagers0.5 to 1.044 to 88Rises through the teens as muscle grows.
Children0.3 to 0.727 to 62Depends on age and size; a child's doctor reads it with growth charts.

Ranges differ slightly between labs and methods. A result just outside the range often isn't a problem on its own; what matters is your eGFR, any change from earlier tests, and the rest of the picture.

Work out your eGFR from creatinine

Enter the creatinine from your report with your age and sex. This uses the CKD-EPI 2021 equation most labs now use.

Sex

Estimated GFR

71 mL/min/1.73m²

Stage

G2: mildly lower

For adults 18 and over. It's less accurate in pregnancy, with very high or low muscle mass, or when kidney function is changing quickly. One result isn't a diagnosis; your doctor reads it with your history and a urine test.

eGFR stages: what your kidney function number means

Most reports now print an eGFR (estimated glomerular filtration rate) worked out from your creatinine, age and sex. These are the KDIGO stages.

StageeGFR (mL/min/1.73m²)What it means
G190 or moreNormal or high filtering
G260 to 89Mildly lower; often normal with age, unless other kidney signs are found
G3a45 to 59Mildly to moderately lower
G3b30 to 44Moderately to severely lower
G415 to 29Severely lower
G5Below 15Kidney failure

Chronic kidney disease means a low eGFR (below 60) or other signs of kidney damage, such as protein in the urine, lasting more than three months. One low result isn't a diagnosis.

What is creatinine?

Creatinine is a waste product made when your muscles use energy. It's produced at a fairly steady rate, carried in the blood, and filtered out by the kidneys into urine.

Because the body makes it steadily and the kidneys clear it, the level in your blood is a good everyday guide to how well the kidneys are filtering. When filtering slows, creatinine builds up and the number rises.

The blood test is often called serum creatinine or S. creatinine, and it's part of a kidney function test (KFT or RFT) along with urea, BUN, sodium and potassium. There's also a urine creatinine test, usually used to work out the urine albumin-to-creatinine ratio, which looks for protein leaking into the urine.

What is eGFR and how does it relate to creatinine?

Creatinine on its own depends on your muscle mass, age and sex, so the same number can be normal for one person and high for another. That's why labs turn it into an eGFR: an estimate of how many millilitres of blood your kidneys filter each minute, adjusted to a standard body size.

Most labs now use the CKD-EPI 2021 equation, which uses creatinine, age and sex (and no longer race). An eGFR of 90 or more is normal; 60 to 89 can be normal for an older adult; below 60 for three months or more is chronic kidney disease.

eGFR is less accurate if you have very high or very low muscle mass, are pregnant, have had an amputation, follow a strict vegetarian or very high-protein diet, or your kidney function is changing quickly. Doctors may then use a cystatin C test as well.

What does high creatinine mean?

A result above your lab's range can come from things that have nothing to do with kidney disease:

  • Dehydration: not drinking enough, heat, vomiting or diarrhoea
  • A lot of muscle, heavy exercise in the day or two before the test, or creatine supplements
  • A large meal of cooked meat in the hours before the test
  • Some medicines, including some painkillers (NSAIDs such as ibuprofen), some blood-pressure medicines and some antibiotics. Never stop a prescribed medicine on your own; ask the doctor who prescribed it.

It can also mean the kidneys are filtering less:

  • Acute kidney injury: a sudden drop, often with dehydration, a serious infection or a blockage
  • Chronic kidney disease: a slow decline, most often from long-standing diabetes or high blood pressure
  • A blockage in the urinary tract, such as an enlarged prostate or kidney stones

A doctor usually repeats the test, looks at your eGFR and compares it with earlier results. A steady result is very different from one that's rising quickly.

What does low creatinine mean?

Low creatinine is rarely a worry. It usually reflects less muscle: in older adults, people with a small build, after a long illness or weight loss, or with a mostly plant-based diet.

It's also normal for it to fall in pregnancy, because the kidneys filter more. Very low levels can go with poor nutrition, severe liver disease or muscle-wasting conditions, which a doctor looks for if there are other signs.

One catch: with low muscle mass, a creatinine that looks "normal" can hide reduced kidney function, which is one reason eGFR and sometimes a cystatin C test are used.

How should you prepare for a creatinine test?

  • It's a small blood sample from a vein. Fasting usually isn't needed, unless other tests at the same visit need it.
  • Avoid hard exercise for a day before, and a large meal of cooked meat the evening before, as both can raise the result.
  • Drink as usual. Being dehydrated can push creatinine up.
  • Tell the lab or your doctor about creatine supplements, any medicines you take, and if you're pregnant.
  • Results usually come back the same day. Many reports include eGFR, urea and BUN alongside.

Who should check creatinine, and how often?

Creatinine is part of most routine check-ups. It's checked more regularly if you have:

  • Diabetes or high blood pressure: at least once a year, with a urine albumin test, because these are the two most common causes of kidney disease
  • Chronic kidney disease: from once a year to every few months, depending on the stage
  • Medicines that affect the kidneys: when they're started and at intervals your doctor sets
  • Heart disease, a family history of kidney disease, or you're over 60

How can you look after your kidneys?

  • Keep blood pressure and blood sugar in your target range. These two matter most for long-term kidney health.
  • Drink enough water for your climate and activity, unless your doctor has told you to limit fluids.
  • Go easy on painkillers. Use NSAIDs such as ibuprofen only as directed and ask a pharmacist if you take them often.
  • Cut down on salt and very salty processed foods; it helps blood pressure and kidneys.
  • Don't smoke, stay active, and keep a healthy weight.
  • Ask before supplements or herbal remedies, especially if your eGFR is low.
  • Medicines and diet changes for kidney disease are your doctor's decision. Some need a lower dose when kidney function is reduced, so always tell any doctor or pharmacist your eGFR.

When to see a doctor

Book a visit

  • Your creatinine is above your lab's range for the first time, or your eGFR is below 60: see a general physician within 1 to 2 weeks for a repeat test and a urine check.
  • Your eGFR is below 30, or your creatinine has risen clearly since your last test: see a nephrologist (kidney specialist) or your doctor within a few days.
  • You have diabetes or high blood pressure and haven't had a kidney check this year: book one in the next month.
  • Swollen ankles or face, foamy urine, passing much more or less urine than usual, or constant tiredness: see a doctor within a few days.

Get emergency help now (call your local emergency number) if someone has:

  • passed very little or no urine for 12 hours or more, especially with swelling or breathlessness
  • severe vomiting or diarrhoea with dizziness or fainting and isn't passing urine
  • chest pain, a very slow or irregular heartbeat, sudden severe weakness or confusion

A creatinine number on its own is rarely an emergency. These signs are.

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Questions people ask

  • Creatinine is a waste product made when your muscles use energy. Your kidneys filter it out of the blood into the urine, so the creatinine level in your blood shows how well your kidneys are filtering. When kidney filtering slows down, creatinine builds up and the number on your blood test rises.

  • For adults, normal serum creatinine is roughly 0.7 to 1.3 mg/dL (62 to 115 µmol/L) in men and 0.6 to 1.1 mg/dL (53 to 97 µmol/L) in women. Children and teenagers run lower. Each lab prints its own range, so compare your result with the reference range on your report, and look at your eGFR too.

  • High creatinine can mean your kidneys are filtering less, from a sudden kidney injury, long-term kidney disease or a urinary blockage. But it's often temporary: dehydration, heavy exercise, a big meat meal, creatine supplements and some medicines can all raise it. A doctor usually repeats the test and checks your eGFR and urine before drawing conclusions.

  • 1.4 mg/dL (124 µmol/L) is just above the usual range for most adults. For a muscular young man it may still mean normal kidney function; for a small older woman it can mean noticeably reduced filtering. That's why the eGFR, which adds your age and sex, matters more than the creatinine alone. See a general physician within 1 to 2 weeks to repeat it.

  • There's no single number. A creatinine that rises quickly over days is more urgent than one that's high but steady for years. Levels several times above normal, or an eGFR below 15, mean the kidneys are failing. Get emergency help if someone with a high creatinine stops passing urine, becomes breathless, confused or very weak.

  • eGFR (estimated glomerular filtration rate) estimates how much blood your kidneys filter each minute. It's calculated from your creatinine, age and sex, usually with the CKD-EPI 2021 equation. A higher creatinine gives a lower eGFR. An eGFR of 90 or more is normal; below 60 for three months or longer means chronic kidney disease.

  • Yes. When you're dehydrated, less blood reaches the kidneys, they filter less, and creatinine rises. It usually comes back down once you're well hydrated, which is why doctors often repeat a high result. Severe dehydration from vomiting or diarrhoea can also injure the kidneys, so get help quickly if you can't keep fluids down.

  • Treat the cause, not the number. Stay well hydrated, avoid heavy exercise and big meat meals before tests, and stop creatine supplements if you take them. If kidney function is reduced, controlling blood pressure and blood sugar protects the kidneys most. Don't take supplements claiming to lower creatinine, and never stop prescribed medicines without your doctor.

  • Usually not. Some labs ask you to avoid cooked meat for about 12 hours and hard exercise for a day before, because both can raise the result. If other tests are done at the same time, such as fasting glucose or a lipid profile, follow the fasting instructions for those.

  • Serum creatinine is measured in blood and shows how well your kidneys are filtering. Urine creatinine is measured in urine, usually to calculate the albumin-to-creatinine ratio (ACR), which shows whether protein is leaking into the urine, an early sign of kidney damage. Doctors often use both, especially for people with diabetes or high blood pressure.

  • Kidney filtering slowly declines with age, but muscle mass falls too, so creatinine may stay the same while kidney function drops. That's why eGFR, which adjusts for age, is more useful than creatinine alone in older adults. An eGFR of 60 to 89 can be normal for an older person if there are no other kidney signs.

  • Creatine supplements raise blood creatinine because the body turns creatine into creatinine, even when the kidneys are healthy. Very high-protein diets and large meat meals can raise it a little too. Tell your doctor about any supplements before a kidney test, and ask before taking them if your eGFR is already low.

  • A kidney function test (KFT), also called a renal function test (RFT), is a group of blood tests that usually includes creatinine, urea or BUN, uric acid, sodium, potassium and often eGFR. Together they show how well the kidneys are filtering and balancing the body's salts. A urine test is often added to check for protein.

Other tests explained

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Sources

  1. MedlinePlus: Creatinine test
  2. Mayo Clinic: Creatinine test
  3. National Kidney Foundation: Estimated glomerular filtration rate (eGFR)
  4. NIDDK (NIH): Chronic kidney disease tests and diagnosis
  5. NHS: Chronic kidney disease, diagnosis
  6. KDIGO 2024 guideline for the evaluation and management of CKD
  7. Inker LA et al. New creatinine- and cystatin C-based equations to estimate GFR without race. NEJM 2021

Updated . Health information, not medical advice. Your doctor knows your full picture; ask them about your result.