C-reactive protein (CRP): why prescribe a dosage?
The doctor usually prescribes a CRP assay to confirm or not the presence of a acute inflammatory syndromeindicating an ongoing immune response.
For example, in case of unexplained fever, this indicator will allow a diagnostic orientation towards a viral, bacterial or even fungal infection, or even the effectiveness of a prescribed treatment. “This makes it possible to detect an infection at an early stage since the CRP level follows a kinetic curve which increases from the 6th hour of inflammation, even before certain symptoms appear, and decreases rapidly after elimination of the cause. The greater the inflammation or infection, the higher the CRP level“says Dr Cédric Villeminot.
>> Namely: for this blood test, it is not necessary to be fasting. “It is not a marker that will be subject to a major influence from diet” underlines the doctor. It is advisable to report any medication taken, as some may distort the results.
High CRP: what are the causes?
Less than 5 mg/l of blood is the normal CRP level in men and in non-pregnant women. This standard may vary depending on the laboratories and the reagents used.
“We observe a slight elevation of CRP in cases of viral infections, such as a cold. The rise in CRP is frank (above 80 to 100 mg/l of blood) in the event of bacterial infections.
Variable rates, higher than normal, are found in chronic diseases such as autoimmune diseases (Crohn’s disease, rheumatoid arthritis, etc.), or even in cancer, such as lymphomas” explains Dr. Villeminot.
Chronic stress or anxiety also tend to raise CRP levels.
>> To know : obese people, smokers or pregnant women have a higher CRP level than the norm.
High CRP: what to do?
A high result means the presence of inflammation in the body. This is a biological indicator, it is better not to “googliser” the results, at the risk of imagining the worst. In effect, this inflammatory marker alone does not allow a diagnosis to be made.
“It is not a decision-making criterion, in particular for diagnosing cancer. Having a CRP around 10 or 12 mg / l is not serious. A high rate aims to guide us to dig further, underlines Dr. Cédric Villeminot. If the CRP is around 30 mg/l for example or remains high, the doctor may prescribe additional tests to look for the cause and the appropriate treatment.
High-sensitivity C-reactive protein: what is it?
To assess the risk of cardiovascular diseases, another test is used: CRP-hs (high sensitivity C-reactive protein), often associated with tests on blood lipids (cholesterol, triglycerides).
The hs-CRP detects lower CRP values than the classic test. A repeated CRP greater than 3 mg/l indicates a high risk of developing cardiovascular disease (ischemic stroke, heart attack, etc.).
Our expert: Dr Cédric Villeminot, general practitioner in Annecy.
