Inflammation markers
CRP Levels by Age: One Range, A Moving Middle
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed September 20266 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
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UK labs use one adult CRP range at every age: under 5 mg/L. Population data tells a different story. A Clinical Chemistry study of 5,748 adults found the median CRP roughly doubled with age, from about 1 mg/L in the youngest decade to about 2 mg/L in the oldest.
Not sure which markers you need? Build your test →Your CRP came back at 4. The range says under 5, so the report calls it normal and nobody rings. You are 34, and something about that 4 will not leave you alone.
You are right to look twice. CRP, or C-reactive protein, is a protein your liver makes when there is inflammation anywhere in the body. The printed range is the same at 34 and at 74. What is typical inside it is not.
1. Is there a CRP chart by age?
No. UK labs publish one adult figure and one note about newborns. There is no band for your thirties and a looser one for your seventies.
The reason is what CRP is for. It is an alarm, not a dial. Clinicians use it to ask whether something inflammatory is happening now, and an alarm works better with one threshold than with six.
2. What UK labs print
CRP is reported in milligrams per litre, written mg/L. Gloucestershire Hospitals gives the adult range as less than 5 mg/L. Its test page adds that the range may not apply to newborns, because an immature immune response means a figure under 5 can still matter there.
Leeds Teaching Hospitals adds the caution that matters most, and it has nothing to do with age.
“A normal CRP does not rule out inflammatory disease.”
— Leeds Teaching Hospitals, pathology test directory
The same page notes that a CRP above 100 mg/L points towards bacterial infection. Between 5 and 100 sits a large, vague middle, which is why CRP is almost never read on its own. Our guide to high CRP levels reads that middle band by band.
3. What actually changes across the decades
The range holds still. The typical value inside it does not.
The largest study of its kind, published in Clinical Chemistry in 2000 by a team at Imperial College and Glasgow, measured CRP in 4,494 adults in Augsburg and 1,254 in Glasgow. It found that the median CRP approximately doubled with age, from approximately 1 mg/L in the youngest decade to approximately 2 mg/L in the oldest, and tended to be higher in women.
Two details make that more useful than it first sounds.
- The people in those studies were the general population, not hospital patients. This is what ordinary looks like.
- The distribution is lopsided. Most results cluster low, and the tail above stretches further with each decade.
The usual explanation is that low-grade inflammation creeps up with age. So a CRP that drifts from 1 to 2 over thirty years is a population trend, not a personal warning.
4. How to read a 3 or a 4 at your age
Put the two facts together and the picture sharpens. A 4 at 34 sits well above the typical value for that decade, yet still inside the range. A 4 at 74 sits closer to ordinary. Both print as normal.
That does not make the younger 4 a problem. CRP rises for plenty of everyday reasons, and most of them pass.
- A cold, a sore throat or a chest infection in the days before the test.
- A dental problem, a healing wound, or recent surgery.
- A hard training session in the 48 hours before the sample.
- A long-term inflammatory condition, which keeps it up rather than spiking it.
The sensible move is to repeat it when you are well rather than chase a single figure. Our normal CRP levels guide works through what lifts the number when you are not ill.
5. hs-CRP is a different number
High-sensitivity CRP measures the same protein with a finer instrument. Standard CRP is built to spot inflammation that has already arrived. hs-CRP resolves the low end, below 5, where the standard test simply reports a small number.
That low end is where the Clinical Chemistry study did its work, and it is why hs-CRP turns up in cardiovascular risk discussions rather than in infection ones. It sits beside a full cholesterol panel for that reason.
The practical warning is simple. Do not compare an hs-CRP against a standard CRP range, or a result from one against a result from the other.
6. Which blood test reports your CRP
Two Helvy panels carry it, and they carry different versions. Helvy's General Energy & Wellness panel (£149) reports standard CRP alongside thyroid, cortisol, vitamin D, vitamin B12, kidney and liver markers and a full lipid set. Helvy's Advanced Heart Health panel (£159) reports hs-CRP beside ApoB, Lp(a) and HbA1c.
Pick on the question you are asking. Broad first look, or cardiovascular risk. A blood test measures biomarkers and offers wellness insight; it does not diagnose. If your CRP sits outside the range on your report, take it to a qualified clinician.
Sample when you are well, not in the week you are shaking off a cold. For the wider picture, inflammation blood tests covers what else gets looked at. The build-my-test tool helps you pick markers.
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See your CRP with the numbers that explain it
Helvy's home blood tests report CRP in UK units with plain-English context, read beside cholesterol, thyroid and vitamin markers rather than on its own. Samples are processed by UKAS-accredited UK labs.
Frequently asked questions
What is a normal CRP level by age in the UK?
UK labs publish one adult range rather than a chart by age. Gloucestershire Hospitals gives it as less than 5 mg/L. Newborns are handled separately, because a figure under 5 can still be significant there.
Does CRP go up with age?
The typical value does. A Clinical Chemistry study of 5,748 adults found the median CRP approximately doubled with age, from approximately 1 mg/L in the youngest decade to approximately 2 mg/L in the oldest. The printed range stays the same.
Is a CRP of 4 normal?
It sits inside the usual adult range of under 5 mg/L at any age. Against population medians it reads higher in a younger person than an older one. A recent infection, dental problem or heavy training session can all account for it.
Is CRP higher in women?
The Clinical Chemistry study found values tended to be higher in females across both populations. UK labs still use one adult range for everyone.
What is the difference between CRP and hs-CRP?
Same protein, finer measurement. hs-CRP resolves the low end below 5 mg/L, which is where cardiovascular risk work happens. Standard CRP is built to spot inflammation that has already arrived. The two figures are not interchangeable.
Does a normal CRP mean there is no inflammation?
No. Leeds Teaching Hospitals states plainly that a normal CRP does not rule out inflammatory disease. It is one marker, read by a qualified clinician alongside your symptoms and history.
Related guides
Normal CRP Levels UK
How high is high, and what lifts it when you are well.
CRP Blood Test UK
What the test measures and when it is used.
Inflammation Blood Test UK
The other markers that get looked at alongside CRP.
Cholesterol Blood Test UK
The panel hs-CRP usually sits beside.
Heart Health Blood Test
ApoB, Lp(a), HbA1c and the rest of the risk picture.
Blood Test Reference Ranges UK
Why normal on a lab report is a population range, not a target.
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