C-reactive proteins are acute-phase proteins in the pentraxin family produced by the liver in response to systemic inflammation in the body. High levels of c-reactive proteins in the blood can indicate the presence of infection, disease, or risk of disease and help medical professionals determine whether a treatment is working and evaluate whether a patient is at risk of developing heart disease. Blood testing of c-reactive protein levels cannot diagnose a specific disease. Results can only tell if inflammation is present.
Many conditions can cause inflammation in the body. Inflammation is a natural result of the aging process and often appears in late pregnancy or in women taking birth control pills. Inflammation may occur in response to viral infections, bacterial infections, and injury. Diseases like heart disease, cancer, and diseases of the connective tissue may also cause elevated c-reactive proteins. Low-grade inflammation may be a response to cigarette smoking, hypertension, and hyperglycemia and may explain the link between certain risk factors and development of disease.
Research studies have shown a strong link between c-reactive protein levels and heart disease. Elevated levels in people who do not show signs of disease indicate a higher risk of developing the disease, especially if the person exhibits other risk factors. The high-sensitivity CRP (hs-CRP) test is a useful test for assessing heart disease risk in individuals with other risk factors because it gives more information than other measures of c-reactive proteins. Heart disease patients with high levels of c-reactive proteins exhibit higher incidences of recurrence and higher mortality rates than patients with lower levels, even when other factors are similar. The presence of inflammation also indicates higher risk for diseases like stroke, diabetes, and possibly cancer, although the link between inflammation and cancer is not strong and needs further study.
Normal levels of c-reactive proteins do not necessarily mean that inflammation is not present. The inflammation associated with certain conditions is less likely to affect c-reactive protein levels. The reason for this is uncertain. Uncommonly low levels of c-reactive protein may be an indication of liver failure.
C-reactive protein levels can be lowered by making lifestyle changes that reduce inflammation in the body. Stopping smoking and reducing alcohol consumption can help. Other healthy habits, like regular exercise and limiting fat intake and processed foods in the diets, will also help reduce inflammation. Increasing consumption of fruits and vegetables and replacing trans fats with healthy fats like olive oil and fish oil will help reduce risk factors for heart disease and other conditions. Individuals with high levels in the past should have blood levels of c-reactive proteins tested regularly to keep track of inflammation in the body.