C-Reactive Protein Test

What is C-reactive protein?

C-reactive protein (CRP) is a substance produced by the liver in response to inflammation.

Other names for CRP are high-sensitivity C-reactive protein (hs-CRP) and ultra-sensitive C-reactive protein (us-CRP).

A high level of CRP in the blood is a marker of inflammation. It can be caused by a wide variety of conditions, from infection to cancer.

High CRP levels can also indicate that there’s inflammation in the arteries of the heart, which can mean a higher risk of a heart attack. However, the CRP test is an extremely nonspecific test, and CRP levels can be elevated in any inflammatory condition.

What does it mean to have a high CRP?

Doctors don’t all agree on the implications of high CRP levels. Some believe there’s a correlation between high CRP levels and an increased likelihood for heart attack or stroke.

The  Physicians’ Health Study  found that among healthy adult men, those with a high level of CRP were three times more likely to have a heart attack than those with low levels of CRP. This was among men who had no previous history of heart disease.

According to the  Cleveland Clinic , the Harvard Women’s Health Study showed that high CRP levels were more predictive of coronary conditions and stroke in women than were high cholesterol levels.

High cholesterol  is a more commonly cited risk factor. The Jackson Heart Study found that hs-CRP may play a role in the development of  type 2 diabetes  in African-Americans.

Doctors may order this test in conjunction with other tests to assess a person’s risk of heart disease or stroke. There is also  new research  that suggests CRP may be used as a predictor in health outcomes related to chronic obstructive pulmonary disease (COPD). Doctors may also order a CRP test to diagnose inflammatory autoimmune diseases, including:

• inflammatory bowel disease (IBD)
• rheumatoid arthritis
• lupus

CRP and heart disease

Expert opinion from the  American Heart Association  in 2013 states that when considering all risk factors, individuals with CRP levels greater than or equal to 2 milligrams per liter (mg/L) likely need more intense management and treatment for heart disease.

Elevated levels of CRP may have an  important role  in identifying those who might need closer follow-up or more intensive treatment after heart attacks or heart procedures.

CRP levels may also be useful in uncovering those at risk of heart disease where cholesterol levels alone may not be helpful.

The  Centers for Disease Control and PreventionTrusted Source  considers these conditions significant risk factors for developing heart disease:

• diabetes
• high blood pressure
• high cholesterol
• smoking
• unhealthful diet
• limited physical activity
• alcohol use  in excess
• being overweight

A family history of heart disease also puts you at higher risk of heart disease.