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CRP (C-reactive protein): what the inflammation marker says and what it does not

C-reactive protein (CRP) is a protein that according to the NVKC, the Dutch society of clinical chemists, is made in the liver and released by the liver into the bloodstream. According to the NVKC, CRP is a general signal substance for inflammation: after an inflammation starts, the amount of CRP in the blood rises sharply within 6 to 8 hours.

According to the NVKC, a raised CRP, or one that rises over consecutive measurements, can point to an acute inflammation, but the test is not specific enough to show the cause. Only a blood test shows how much CRP is in the blood.

The upper limit of CRP differs by laboratory: Unilabs gives 0 to 5 mg/l, Certe below 5 mg/L from age 18, Diagnostiek voor U below 6 mg/L and Star-SHL 0 to 10 mg/l.

Doctor's Assessment Included

CRP is a protein made by the liver that rises sharply in the blood within 6 to 8 hours of the start of an inflammation. The upper limit differs by laboratory: 5 mg/l at Unilabs and Certe, 6 at Diagnostiek voor U and 10 at Star-SHL.

  • A raised CRP can point to an inflammation or infection, but does not show where it is or what causes it.
  • Once an inflammation subsides, CRP can fall quickly: its half-life is about 19 hours, which makes recovery easy to follow with CRP.
  • A normal CRP does not rule out an infection that has just started, because CRP only rises above 5 mg/l about 6 hours after an inflammation begins.

Reference Ranges

See the value that applies to you:

Choose male or female — this range differs by sex.

Enter your age — this range changes with age.

This range also depends on context such as cycle phase or sample material; the highlighted rows apply to your group.

Male Your group
mg/l
Normal < 10 High
Female Your group
mg/l
Normal < 10 High

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

CRP (C-Reactive Protein): what Dutch laboratories use

The upper limit runs from 5 mg/l at Unilabs to 10 mg/l at Star-shl.

Reference ranges by group, in mg/l
Star-shl · Everyone 0–10 mg/l
0 10
Unilabs · Everyone 0–5 mg/l
0 5
Certe · Everyone · 18 years and older · a limit, not a range < 5 mg/L
5
Diagnostiek voor U · Everyone · a limit, not a range < 6 mg/L
6
0 11 mg/l

Source: Star-shl

Source: Unilabs

Source: Certe

Source: Diagnostiek voor U

Each value as the laboratory itself publishes it, retrieved in 2026.

CRP (C-Reactive Protein): what this test measures

The CRP test measures the amount of C-reactive protein in the blood, in milligrams per litre (mg/l). According to the NVKC, the concentration of CRP can rise by a factor of 1000 in an inflammation.

CRP (C-Reactive Protein): why this value matters

According to the NVKC, CRP helps to show or rule out an inflammation or infection, and to follow the effect of a treatment. According to the NVKC, the rise in CRP is often measurable before symptoms of an inflammation, such as pain or fever, are noticeable.

According to the NVKC, CRP can fall quickly again when an inflammation subsides, which makes the test well suited to establishing recovery.

CRP (C-Reactive Protein): how the blood test works

Referral
No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw
A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Which test
Blood count checkup · €109,- · General checkup · €199,-
Where
650+ draw sites run by independent laboratories across the Netherlands. Draw sites

CRP (C-Reactive Protein): how to prepare

  1. Been ill? Wait a little

    Required

    Had a fever, an infection or a vaccination in the past 2 weeks? Wait with the draw until you are fully recovered. These values react to inflammation and would give a distorted picture.

  2. Better no hard training beforehand

    Recommended

    Hard exercise in the 48 hours before can raise this value temporarily. Plan the draw on a rest day if you can.

  • Water is always fine. Drink as usual beforehand, it makes the draw easier.
  • Take your usual medication, unless your own doctor told you otherwise.

CRP (C-Reactive Protein): when is testing worthwhile?

According to the NVKC, a CRP test is used to find out whether there may be inflammation, for example in the abdomen, to gain insight into inflammatory diseases such as some forms of rheumatism or autoimmune diseases, and to follow the severity of an inflammation and the success of the treatment. According to the NVKC, CRP is used after an operation to see in time whether an infection develops.

CRP (C-Reactive Protein): symptoms of a high or low value

Low Levels

A low CRP fits healthy people without inflammation: Star-SHL and Unilabs give 0 mg/l as the lower limit. Shortly after an inflammation starts, CRP can still be normal, because according to a 2003 review CRP rises above 5 mg/l within about 6 hours of a stimulus. According to that review, less CRP is made in liver failure, and statins lower CRP independently of their effect on blood fats.

High Levels

According to the NVKC, a raised CRP can point to an acute inflammation, and according to the NVKC most inflammations lead to CRP values above 100 mg/l. According to a 2003 review, dead tissue is a strong stimulus, with a large CRP response after a heart attack, and CRP stays persistently raised in some people with a chronic inflammatory disease such as rheumatoid arthritis. According to that review, lupus (SLE) causes no large CRP rise despite clear inflammation.

If CRP stays persistently above 10 mg/l, according to that review a full history and physical examination are indicated, ideally with further tests for the cause.

CRP (C-Reactive Protein): causes of a low or high value

What lowers the value

  • Liver failure

    The liver makes CRP, and in liver failure less CRP is produced.

  • Statins

    Statins, cholesterol-lowering medicines, lower CRP, separately from their effect on cholesterol.

What raises the value

  • Infection or acute inflammation

    A raised or rising CRP can point to acute inflammation or infection.

  • Dead tissue

    Dead tissue is a strong trigger for CRP; a heart attack is followed by a large CRP response.

  • Chronic inflammatory disease

    In some people with a chronic inflammatory disease such as rheumatoid arthritis, CRP stays raised; lupus (SLE), an autoimmune disease, does not cause a large CRP rise despite clear inflammation.

  • Overweight

    A higher BMI goes with a higher baseline CRP, the CRP value without inflammation, and weight loss lowers it.

  • The pill and hormone tablets

    The contraceptive pill and hormone therapy taken as tablets after menopause go with a higher CRP without inflammation; hormone therapy through the skin does not.

CRP (C-Reactive Protein): lifestyle and this value

A raised CRP is one to discuss with your GP: according to the NVKC, CRP is a general signal substance that warns the doctor when further tests into the cause and treatment are needed. According to a 2003 review, a higher BMI goes together with a higher baseline CRP, the CRP value without inflammation, and weight loss lowers the CRP value.

CRP (C-Reactive Protein): frequently asked questions

Does eating affect CRP in an inflammatory response?

No, according to a 2003 review, CRP values in an acute inflammatory response are not affected by eating, and they show no variation over the day.

What is the difference between CRP and hs-CRP?

Hs-CRP is a more sensitive CRP measurement that according to the NVKC can also measure small amounts of CRP, and it is used for the risk of cardiovascular disease. According to the NVKC, the ordinary CRP test does not measure the very small amounts of CRP the body makes over a long time in cardiovascular disease.

What is the difference between CRP and the ESR?

According to the NVKC, the ESR (erythrocyte sedimentation rate) is often requested for the same question as CRP, but it reacts more slowly and often stays raised long after the illness.

CRP (C-Reactive Protein): sources

  1. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  2. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  3. Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
  4. Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
  5. Pepys MB, Hirschfield GM. C-reactive protein: a critical update. J Clin Invest 2003;111(12):1805-1812. (retrieved 2026) pmc.ncbi.nlm.nih.gov
  6. NVKC, Alles over testen: CRP, allesovertesten.nl, geraadpleegd 2026-10-06 (retrieved 2026) allesovertesten.nl

Test Products

This marker is included in the following test panels.

Blood count & immunity

Blood count checkup

A blood test with 10 values for blood count and immunity — haemoglobin, haematocrit, white cells with differential, platelets, MCV, MCH, MCHC, CRP and ESR — for insight into blood and inflammation.

Hemoglobin Hematocrit Leukocytes (WBC) Leukocyte Differential Platelets (Thrombocytes) MCV (Mean Corpuscular Volume) MCH (Mean Corpuscular Hemoglobin) MCHC (Mean Corpuscular Hemoglobin Concentration) CRP (C-Reactive Protein) Erythrocytes (RBC) Ferritin
€109,-
General checkup

General checkup

A broad blood test covering 18 values across liver, kidneys, thyroid, heart, vitamins and blood count.

ALT (Alanine Aminotransferase) GGT (Gamma-Glutamyl Transferase) Creatinine eGFR (Estimated Glomerular Filtration Rate) TSH (Thyroid Stimulating Hormone) Total Cholesterol HDL Cholesterol LDL Cholesterol Triglycerides Glucose (Fasting) Vitamin D (25-OH) Vitamin B12 Ferritin Hemoglobin Leukocytes (WBC) Platelets (Thrombocytes) CRP (C-Reactive Protein) MCV (Mean Corpuscular Volume) Cholesterol/HDL Ratio Non-HDL Cholesterol LDL/HDL Ratio
€199,-

Medical reviewer

Medical standards

Dr. Naimi oversees the medical standards behind our content and assessments.

Medical policy
CIBG Ministerie van Volksgezondheid,
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CRP (C-Reactive Protein)

€18,-