A result that gives no cause for concern is a CRP level below 8 mg/L – this is the norm for older children and adults. For newborns and infants, CRP should not exceed 5 mg/L. After birth, it usually stabilizes at a level not exceeding 3 mg/L.
An elevated or high CRP result is most often a sign of infection or inflammation. From the perspective of effective treatment, including the use of antibiotics, it is important to determine whether we are dealing with a viral or bacterial infection. This can be determined based on the CRP test result (the result is expressed in mg/L).
These concentrations indicate a high probability of developing a viral infection. Infections of this type are characteristic of most upper respiratory tract infections, as well as colds and flu. Viral infections are mainly caused by RSV, HSV, EBV (Epstein-Barr Virus), rhinoviruses, adenoviruses, and influenza and parainfluenza viruses.
Especially in the case of a throat infection, which manifests with severe pain and the presence of purulent coating on the tonsils, the CRP concentration may increase. Most often, if CRP does not exceed 40, we may be dealing with mononucleosis caused by the EBV virus.
Viral infections are treated symptomatically; antibiotics are not used under any circumstances.
A child with CRP 40 – 100 most likely has a developing bacterial infection, for which antibiotic treatment is used. Local infections, e.g., bacterial purulent tonsillitis caused by streptococci developing in the throat, can cause CRP to rise above 40. Other bacterial infections associated with urinary tract or digestive system infections (Escherichia coli, Salmonella, Helicobacter pylori) can also cause an increase in C-reactive protein.
CRP is also used to monitor treatment effectiveness – CRP should decrease after antibiotic administration.
If the child has no symptoms of infection, CRP above 40 indicates an intensifying inflammatory state in the body. This requires further diagnosis and consultation with a doctor.
High CRP in a child – at 100 or higher values – indicates dangerous bacterial infections. It may also indicate severe inflammation, toxin poisoning, or liver damage.
In special cases, CRP levels can increase even several dozen times above the norm – very high CRP can exceed 1000 mg/L (e.g., pneumonia).
There is no such thing as too low CRP – a test result cannot be “too low.” In laboratory diagnostics, a strictly defined norm applies – a result from 0 to 8 is considered normal.
There is no such thing as too low CRP – a test result cannot be “too low.” In laboratory diagnostics, a strictly defined norm applies – a result from 0 to 8 is considered normal.
In children, especially those under 5 years of age, blood for testing is taken from a fingertip. This saves the child the “needle trauma” of drawing blood from a vein. A small drop of blood is enough to check the CRP result.
Rapid diagnostic tests using point-of-care technology come to the rescue. CRP strip tests available in pharmacies allow for a blood test result from a finger prick within just a few minutes, enabling quick and effective treatment.
The test is performed in cases of:
Most acute respiratory tract infections (even over 80%) are viral – in which CRP is usually low or slightly elevated.
Bibliography:
[1] Sapilak B. et al.: Evaluation of the usefulness of C-reactive protein measurements by semi-quantitative and quantitative methods in the diagnosis of upper respiratory tract infections, Family Medicine & Primary Care Review 2012, 14, 3: 431–433.
[2] Jaye D.L., Waites K.B.: Clinical applications of C-reactive protein in pediatrics. Pediatr. Infect. Dis. J. 1997, 16, 735-47.
[3] Huddy J. et al: Point-of-care C reactive protein for the diagnosis of lower respiratory tract infection in NHS primary care: a qualitative study of barriers and facilitators to adoption, BMJ Open 2016.
[4] A. Muszyńska et al.: Usefulness of rapid CRP tests (NycoCard II® CRP) in the daily practice of a family doctor in terms of rationalizing indications for antibiotic therapy in acute infections, Family Medicine & Primary Care Review 2007, 9, 4: 998–1006.
[5] Biernat M.: Upper respiratory tract infections.
Diagnostic tests for self-administration. Select a product to learn details, find out how to perform the test and make a purchase on our website
Rapid, at-home blood test for CRP protein levels (virus or bacteria)
