Elevated C-Reactive Protein (CRP)

C-reactive protein (CRP) is a substance produced by the liver that increases in the presence of inflammation in the body. An elevated C-reactive protein level is identified with blood tests and is considered a non-specific “marker” for disease. It can signal flare-ups of inflammatory diseases such as rheumatoid arthritis, lupus, and vasculitis. Data from a large number of studies suggest that over time, chronic low-level inflammation in the body can contribute to many serious, age-related diseases including heart disease, some forms of cancer, and neurodegenerative conditions such as Alzheimer’s and Parkinson’s disease. In addition, recently published results from the long-term ARIC study (Atherosclerosis Risk in Communities) suggest that inflammation alone – regardless of cholesterol levels – is a predictor of heart disease.

What are the symptoms of elevated C-reactive protein?

Elevated CRP levels have no outward, noticeable symptoms.

What is the significance of elevated C-reactive protein?

Elevated CRP can signal many different conditions, including cancer, cardiovascular disease, infection, and autoimmune conditions such as rheumatoid arthritis, lupus, and inflammatory bowel disease.

What are the causes of elevated C-reactive protein?

The chronic inflammation behind an elevated CRP level may be influenced by genetics, a sedentary lifestyle, too much stress, and exposure to environmental toxins such as secondhand tobacco smoke. Diet has a huge impact, particularly eating habits that include a lot of refined, processed and manufactured foods.

How is elevated C-reactive protein diagnosed?

There are two tests for CRP. One can detect a non-specific elevation of CRP that occurs with general inflammatory changes in the body. The other test, hs-CRP, is a measure of inflammation in blood vessels. This is the test utilized to help evaluate heart disease risk.

In quantifying cardiac risk, physicians look at a very narrow range of C-reactive protein levels, from zero to 3.0 and above. This requires a special test called high-sensitivity C-reactive protein (hs-CRP), which may be able to reveal inflammation at the micro-vascular level. If this test shows that CRP is less than 1.0 mg per liter of blood, the risk of heart disease is considered low; if it is between 1.0 and 3.0, the risk is average; and if it is above 3.0, the risk is deemed high.

In 2020, the Journal of the American Heart Association (AHA) published results from the long-term ARIC study that reported specifically on hs-CRP as a predictor of heart disease risk. In that report, 9,748 individuals without heart disease at the start of the study, with a median hs-CRP of 2.4, were followed for many years (between 12.8 and 19.5). Initially, their risk of cardiovascular disease was predicted based on lipid (cholesterol) scores.  Over the course of the study, there were 1,574 cardiovascular events (heart attacks and strokes, some fatal). Those whose hs-CRP was equal to or above 2.4 at the start of the study, indicating inflammation, were more likely to have experienced a cardiac event than those whose score was below 2.4. The incidence of these events was the same in those whose lipid profiles indicated a low risk as those who were deemed high risk. Researchers concluded that inflammation alone, independent of lipid profiles, is a risk factor for cardiac events.

The Mayo Clinic suggests that hs-CRP testing is most useful for evaluating patients with an intermediate risk of heart disease, meaning a 10-20 percent risk of having a heart attack in the next 10 years. Those already known to be at higher risk wouldn’t benefit from the test. While the Mayo Clinic doesn’t advise routine hs-CRP testing in patients who are low risk for heart disease, some physicians, including Dr. Weil, believe that all adults should have an hs-CRP test whenever their cholesterol is tested.

People who have certain arthritic or autoimmune conditions tend to have elevated C-reactive protein levels because inflammation underlies these disorders. Arthritis may push test results far beyond the range used to assess heart disease risk. In most of these people, CRP levels tend to be above 100 mg/L. The hs-CRP test isn’t used for patients with rheumatoid arthritis, inflammatory bowel disease, or other autoimmune conditions. Instead, doctors evaluate inflammation with a test that measures levels in excess of 10 mg/L. When checking CRP for arthritic and autoimmune disorders, a level of 10 mg/L or lower is considered “normal.”

Because an hs-CRP test isn’t useful to assess cardiovascular risk among people with inflammatory diseases, these patients have to rely on other established risk factors, such as high blood pressure or high cholesterol, whether or not they smoke, carry excess weight, and are at increased risk of diabetes. In addition to advising the adoption of  proven measures for reducing the risk of cardiovascular disease, including exercise, keeping weight under control, practicing stress reduction techniques, and getting adequate sleep, Dr. Weil recommends that people with chronic inflammatory disorders make an effort to reduce inflammation and their risk of heart disease by following an anti-inflammatory diet.

What is the conventional treatment of elevated C-reactive protein?

Conventional physicians may prescribe the same drugs (statins) used to lower LDL cholesterol to address elevated levels of CRP. In addition, they will typically recommend exercise and weight loss where appropriate, since both can help lower CRP levels. In general, conventional physicians recommend the same lifestyle changes shown to reduce heart disease – diet, exercise, not smoking, drinking less alcohol, following a heart-healthy diet – to lower elevated C-reactive protein levels.

What therapies does Dr. Weil recommend for elevated C-reactive protein?

Dr. Weil recommends an anti-inflammatory diet that includes two to three servings of fish such as salmon or sardines per week. If you don’t eat fish, he suggests taking fish oil supplements. He also recommends taking anti-inflammatory herbs including ginger and turmeric and following your doctor’s recommendations for heart health. That means quitting smoking, watching your diet (particularly avoid foods with a lot of flour and sugar), and getting regular exercise: research indicates that as fitness levels decline, C-reactive protein levels go up.

Sources
Quispe R, Michos ED, Martin SS, Puri R, Toth PP, Al Suwaidi J, Banach M, Virani SS, Blumenthal RS, Jones SR, Elshazly MB. “High-Sensitivity C-Reactive Protein Discordance With Atherogenic Lipid Measures and Incidence of Atherosclerotic Cardiovascular Disease in Primary Prevention: The ARIC Study.” J Am Heart Assoc. 2020 Feb 4;9(3):e013600. doi: 10.1161/JAHA.119.013600. Epub 2020 Jan 30. PMID: 32013698; PMCID: PMC7033866. https://pubmed.ncbi.nlm.nih.gov/32013698/mayoclinic.org/tests-procedures/c-reactive-protein/basics/definition/prc-20014480
nlm.nih.gov/medlineplus/ency/article/003356.htm
webmd.com/a-to-z-guides/c-reactive-protein-crp

Reviewed by Benjamin S. Gonzalez, M.D., May, 2016. Updated August 2022.