Creatinine is a waste product from muscles that the kidneys filter out, so a higher level can mean the kidneys are filtering less. Typical upper limits are about 1.2 mg/dL (106 µmol/L) for men and 1.0 mg/dL (88 µmol/L) for women. But creatinine also depends on muscle mass, hydration, diet and exercise, which is why it is read together with eGFR and repeated before conclusions are drawn.
| Category | Reference range |
|---|---|
| Men | about 0.7–1.2 (60–106) mg/dL (µmol/L in brackets) |
| Women | about 0.5–1.0 (45–90) mg/dL (µmol/L in brackets) |
| Example: 1.3 mg/dL | = about 115 µmol/L mg/dL (µmol/L in brackets) |
| Example: 120 µmol/L | = about 1.36 mg/dL mg/dL (µmol/L in brackets) |
Ranges vary by lab, age and body size; use the range on your report. 1 mg/dL = 88.4 µmol/L.
Muscles produce creatinine at a fairly steady rate, and healthy kidneys remove it. When filtering slows, creatinine builds up. The relationship is not linear: early on, kidney function can fall noticeably before creatinine moves much, while later small rises reflect larger losses. That is why labs convert it into eGFR, which accounts for age and sex.
Creatinine on its own also reflects muscle. A muscular man, a bodybuilder or someone who ate a large meat meal the evening before may have a creatinine slightly above range with normal kidneys. A frail older person with little muscle can have a "normal" creatinine despite reduced kidney function.
For most women these values are above the range; for men they are at or just above the upper limit. Whether they matter depends on eGFR, your age and muscle mass, and the trend. A stable 1.3 for years in a muscular man is very different from a rise from 0.8 to 1.3 over a few months.
Doctors usually repeat the test, ideally after avoiding heavy exercise and large meat meals for a day or two and being well hydrated, and check a urine sample for protein (the albumin-to-creatinine ratio, ACR).
It also helps to bring older results to your appointment. Kidney function is judged largely by its trend, and a value from two or three years ago is often the quickest way to tell a long-standing baseline from a recent change.
When creatinine is high and eGFR is below 60, the next question is whether it is new or long-standing. Chronic kidney disease is only diagnosed when reduced eGFR or other kidney damage markers persist for at least three months. A sudden change between two tests, by contrast, may be an acute kidney injury and is acted on more quickly.
If creatinine is unreliable because of very high or very low muscle mass, doctors may measure cystatin C, another marker that does not depend on muscle.
A raised creatinine should be discussed with your GP or doctor, who will usually repeat it with an eGFR and a urine test. Seek urgent help (NHS 111, urgent care, A&E or the emergency room) if a high creatinine comes with:
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No need to decode the numbers yourself: take a photo of the report and the app explains “High creatinine” and the rest in plain words — what is normal and what deserves attention.
App StoreGoogle PlayWeb versionThat your kidneys may be filtering less than expected, or that something else such as muscle mass, dehydration or exercise has raised it. Your doctor will look at eGFR, urine tests and the trend.
Not necessarily. It is slightly above the usual range for women and around the upper limit for men. A repeat test and eGFR help show whether kidney function is actually reduced.
There is no single number, because it depends on your baseline and muscle mass. A fast rise from your usual value, or a high creatinine with reduced urine, swelling or a high potassium, needs urgent attention.
Yes. Not drinking enough, vomiting or diarrhoea can raise creatinine temporarily. It usually returns to baseline once you are rehydrated.
Yes. Intense exercise, especially weight training, can raise creatinine for a day or two. Avoid heavy workouts before a kidney blood test.
About 1.36 mg/dL. Divide µmol/L by 88.4 to get mg/dL.
This material is for general information only. It is not a medical opinion and does not replace a consultation with a doctor. Reference ranges depend on the laboratory and the method — rely on the range printed on your own report. Your doctor makes the final interpretation.
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