CRP is short for C-reactive protein (S-CRP). In healthy individuals, the liver continuously produces small amounts of CRP. Its amount increases considerably in connection with infections, inflammation, and tissue damage in the body.
In inflammation and tissue damage, white blood cells secrete a substance that accelerates the production of CRP in the liver. CRP reacts quickly to inflammation, and its concentration increases within 6–12 hours of the onset of the inflammation. When the cause of the inflammation is eliminated, the CRP concentration also decreases relatively quickly. CRP can also be used for monitoring the effectiveness of treatment. If the increase in CRP is caused by a bacterial infection and the treatment given is not working, the CRP value does not decrease; it can actually even increase.
A high-sensitivity CRP test (S-hsCRP) has been developed in recent years. This shows the precise concentration of C-reactive protein in the blood, even if the concentration is within the normal range. The S-hsCRP and S-CRP tests measure the levels of the same molecule, but S-hsCRP has been developed to measure lower levels of the molecule. High-sensitivity CRP indicates cardiovascular disease in healthy individuals. Small amounts of CRP are produced in the body because of a continuous slight inflammation in the inner walls of the arteries, which can lead to atherosclerosis, or a buildup of fat on the artery walls, before long.
When should CRP be measured?
CRP should be tested in connection with the following:
- When suspecting sudden inflammation
- When wanting to discern between bacterial and viral infections
- When wanting to monitor the effectiveness of treatment for a bacterial infection
- When suspecting chronic inflammation, such as rheumatoid arthritis or spinal arthritis
- When wanting to monitor the effectiveness of treatment for chronic inflammation, such as how well medications for rheumatoid arthritis have worked
- After surgery, to exclude inflammation
- In assessing the risk of cardiovascular disease (S-hsCRP)
Depending on the location of the inflammation, tissue damage, or infection, the symptoms can include the following:
- Stomach pain
- Decrease in general health
- Poor fitness
- Feeling sick
- Joint pain and swelling, and morning stiffness of joints
- Chest pain and shortness of breath
What does the CRP test measure?
The concentration of CRP in the blood increases quickly in several infections and in other inflammation and tissue damage. The CRP value can reliably assess the severity of the disease and treatment response. However, the CRP test does not locate the inflammation or show what is causing the disease; further examinations based on the symptoms are required for that.
CRP does not necessarily increase in local infections, such as a bladder infection. Individual diseases of the upper respiratory tract can also often increase the CRP value considerably, and CRP is not always useful for discerning between bacterial and viral diseases.
High-sensitivity CRP (S-hsCRP) measures the risk of coronary artery disease and common arterial disease. This test should not be taken when there is another known inflammatory condition in the body, such as rheumatoid arthritis or an infection.
How to interpret the CRP test result?
Normally, the result is:
S-CRP: <10 mg/l
S-hsCRP Assessment of cardiovascular disease risk:
- <1 CRP mg/l: Low risk1
- 1–3 CRP mg/l: Moderate risk
3 CRP mg/l: High risk
5 CRP mg/l: An inflammatory disease has to be excluded and the analysis repeated after two or more weeks, if necessary.
In order to assess cardiovascular disease risk, lipid values (S-Lipids) should also be checked in connection with the CRP level.
Please contact your physician or other healthcare professional if you suspect an illness or need help interpreting the results.
What can cause elevated S-CRP values?
High CRP values can be seen in:
- Bacterial infections (in viral diseases, CRP often increases only slightly)
- respiratory tract infection (pneumonia)
- abdominal infection (diarrhoea, cholecystitis, pancreatitis)
- genital and and urinary tract infection (uteritis or pyelonephritis)
- skin infection (erysipelas)
- In connection with the breakdown of cells (malignant tumours, chronic infections, injury, and after surgery)
What can cause decreased S-CRP values?
CRP occurs in very low concentrations in healthy individuals.
The most typical additional S-CRP tests:
- ESR that indicates chronic and viral infections (2203 B-La)
- Comprehensive picture of lipid values (2245 S-Lipids)
SYNLAB test list: C-reactive protein https://www2.synlab.fi/laboratoriokasikirja/tutkimuskuvaukset/crp/
SYNLAB C-reactive protein https://www.yml.fi/tuotekuvaus_show.php?tuotenro=77
Terveyskirjasto health library: CRP (P-CRP) https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=snk03052&p_hakusana=crp
Terveyskirjasto health library: C-reaktiivinen proteiini https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=ltt00488&p_hakusana=crp
Potilaan lääkärilehti (Patient's Medical Journal): CRP varmistaa diagnoosin https://www.potilaanlaakarilehti.fi/uutiset/crp-varmistaa-diagnoosin/
Lab Test online: C-reactive protein (CRP) https://labtestsonline.org.uk/tests/c-reactive-protein-crp
Lab Test online: hs-CRP https://labtestsonline.org.uk/tests/hs-crp
Fasting is not required
This examination does not require fasting