Kidney and organ health
Creatinine Blood Test: What a High Result Really Means
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed July 20269 min read
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Creatinine is a waste product your kidneys filter out. In UK adults without kidney disease it usually runs 64 to 104 µmol/L for men and 49 to 90 for women. A high reading is not always a kidney problem. Muscle, meat and dehydration all raise it too.
Not sure which markers you need? Build your test →As of July 2026. A flagged creatinine or eGFR is one of the most common reasons people go looking for answers after a blood test. The number sounds alarming. Often it is not. This guide explains what creatinine is, what a normal level looks like in the UK, and the everyday things that push it up without any kidney disease at all.
The key idea is simple. Creatinine is a useful marker, but it is easily nudged. Reading it in context matters more than the single figure.
1. What is creatinine, and why is it tested?
Creatinine is a waste product. Your muscles make it every day as they use energy, breaking down a compound called creatine phosphate. It then travels in your blood to your kidneys.
Healthy kidneys filter creatinine out into your urine at a steady pace. So the level left in your blood is a rough gauge of how well that filtering is working. If the kidneys slow down, creatinine backs up and the blood level rises.
That is why it appears on almost every routine blood panel. It is cheap, stable and quick to measure. It is not a perfect marker, though, and the rest of this guide is about the ways it can mislead.
2. What is a normal creatinine level in the UK?
UK labs report creatinine in micromoles per litre (µmol/L). According to Kidney Care UK, the typical ranges in people without chronic kidney disease are:
| GROUP | TYPICAL RANGE |
|---|---|
| Men | 64–104 µmol/L |
| Women | 49–90 µmol/L |
Men run higher because they usually carry more muscle. Ranges also shift a little with your age, build and ethnicity, so the exact cut-off your lab prints may differ slightly from these figures.
One number rarely tells the whole story. This is why creatinine is best read alongside eGFR and urea, the two markers that turn it into a picture of kidney function. Our kidney function test guide walks through the full set.
3. How creatinine becomes your eGFR
You will often see an eGFR reported next to creatinine. eGFR stands for estimated glomerular filtration rate. It is a calculation, not a separate blood test.
The NHS explains it plainly: a doctor uses your creatinine result, plus your age, size and sex, to estimate how much waste your kidneys clear per minute. Healthy kidneys should filter more than 90 ml/min, and eGFR is then grouped into five stages.
| STAGE | eGFR (ml/min) |
|---|---|
| G1 | Above 90, with other signs of kidney damage |
| G2 | 60–89, with other signs of kidney damage |
| G3a / G3b | 45–59 / 30–44 |
| G4 | 15–29 |
| G5 | Below 15 |
One point matters here. eGFR naturally drifts down with age, by roughly 1 ml/min a year after 40. So a healthy 75-year-old may sit around 50 to 60 and be perfectly well. A stage on its own is not a diagnosis, which is exactly why a doctor looks at the trend, not one reading.
4. Why a high creatinine is often not a kidney problem
Here is the part most people are not told. Because creatinine comes from muscle and food, several harmless things raise it. A high reading is a prompt to look closer, not a verdict.
“People with a higher muscle mass will produce more creatinine and therefore have higher levels, but this doesn’t necessarily mean that they have CKD.”
— Kidney Care UK
The common, non-kidney reasons a creatinine reads high:
- High muscle mass. More muscle makes more creatinine. A lean, well-trained person can sit above the range and be entirely healthy.
- A big meat meal before the test. Cooked meat contains creatinine, so a heavy protein meal the night before can nudge the result up.
- Dehydration. Less fluid concentrates the blood, which lifts creatinine. It usually settles once you rehydrate.
- Intense exercise. A hard workout in the day or two before can raise it temporarily.
- Creatine supplements. Creatine converts to creatinine, so it can flag a falsely high result. Our guide on creatine and creatinine covers this in full.
This is also why creatinine can miss the opposite problem. Someone with very low muscle mass may have “normal” creatinine while their kidneys are struggling. For those cases, a marker called cystatin C is not thrown off by muscle at all.
5. When does a creatinine result actually matter?
A single high reading is rarely the full answer. What counts is whether the change is real and sustained. A few things move it from noise to signal:
- It stays high on a repeat test taken when you are rested, hydrated and have not loaded up on protein or creatine.
- Your eGFR is falling over time, not just sitting at a stable, age-appropriate level.
- Other markers shift too, such as urea, or protein showing up in your urine.
Kidney function also has known drivers worth watching, mainly high blood pressure and raised blood sugar. Checking those alongside your kidney markers gives a fuller picture than creatinine alone.
Helvy's Thyroid & Vital Organs panel (£159, 16 markers) measures creatinine, eGFR and urea alongside liver, thyroid and cholesterol markers in one home finger-prick test. Creatinine and urea also feature in the General Energy & Wellness panel (£149). A full blood count adds the wider context many people want at the same time. This is information to help you have a better conversation with your GP, not a diagnosis.
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Frequently asked questions
What is a normal creatinine level in the UK?
In people without chronic kidney disease, Kidney Care UK gives a typical range of 64 to 104 µmol/L for men and 49 to 90 for women. Men run higher because they usually carry more muscle. Your lab's exact cut-off may vary with age and build. This is general information, not medical advice.
Does high creatinine always mean kidney disease?
No. Creatinine comes from muscle and meat, so high muscle mass, a big protein meal, dehydration, hard exercise and creatine supplements can all raise it without any kidney problem. A high reading is a prompt to repeat the test in better conditions and look at your eGFR trend.
What is the difference between creatinine and eGFR?
Creatinine is the measured waste product. eGFR is a calculation that turns your creatinine into an estimate of kidney filtering, using your age, size and sex. The NHS treats an eGFR above 90 ml/min as healthy, though it drifts down slowly with age.
Should I stop creatine before a creatinine test?
Creatine can lift your creatinine and make eGFR look lower than it is. If you want a cleaner reading, many people pause it for a few days before testing and stay well hydrated. If a result is high or keeps rising, speak to your GP.