Elevated C-reactive Protein (CRP)
What is elevated C-reactive protein?
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. Data from a large number of studies suggest that over time chronic, imperceptible, low-level internal inflammation can lead to many serious, age-related diseases including heart disease, some forms of cancer and neurodegenerative conditions such as Alzheimer's and Parkinson's disease.
However, CRP levels don't appear to help predict the risk of heart disease in patients already being treated for risks such as high blood pressure or high LDL ("bad") cholesterol. A 2010 analysis of British data on 4,853 patients found that C-reactive protein levels didn't yield any more information about the risk of heart disease than LDL ("bad") cholesterol levels or high blood pressure in patients who already were being treated with a cholesterol-lowering statin drug or with medication to lower blood pressure.
For those reasons, the researchers concluded that measuring CRP in patients with other known risk factors for heart disease may not be necessary. These results, presented at a 2010 American Heart Association meeting and later published in the European Heart Journal, conflict with findings from an earlier study with more than 17,000 patients¸ which showed that treating elevated CRP with statin drugs reduced cardiovascular events by 37 percent in healthy individuals whose only risk factor for heart disease was elevated C-reactive protein levels. This earlier study called JUPITER (Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin) found that patients taking the drug rosuvastain were half as likely to need angioplasty or bypass surgery, half as likely to suffer a heart attack or stroke, and 20 percent less likely to die than study participants who received the placebo. That study was published in 2008 in The New England Journal of Medicine.
What are the symptoms of elevated C-reactive protein?
Elevated CRP levels have no outward, noticeable symptoms.
What are the causes of elevated C-reactive protein?
The inflammation signaled by CRP is 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 one that contains a lot of refined, processed and manufactured foods.
How is elevated C-reactive protein diagnosed?
CRP levels can be measured via a blood test. In evaluating cardiac risk, physicians look at a very narrow range of CRP 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; if it is above 3.0, the risk is deemed high.
The American Heart Association (AHA) recommends CRP testing when doctors aren't sure how to treat patients with an intermediate risk of heart disease, such as a 10-20 percent risk of having a heart attack in the next 10 years However, AHA guidelines do not recommend CRP testing for individuals at either high risk of low risk. (Other physicians, including Dr. Weil, think that all adults should have an hs-CRP test whenever their cholesterol is tested.)
There are two tests for elevated C-reactive protein. One can show a non-specific elevation of CRP that occurs with general inflammatory changes in the body; the other test is hs-CRP - highly sensitive CRP - which is a measure of inflammation in blood vessels. This is the test needed to help establish heart disease risk.
People who have arthritic conditions tend to have elevted C-reactive protein levels because inflammation underlies these disorders. Arthritis may push test results far beyond the range used to assess heart disease risk. When inflammation levels are being assessed in patients with rheumatoid arthritis, inflammatory bowel disease or other autoimmune conditions, the hs-CRP test is not used. Instead, inflammation is evaluated with a test that measures levels in excess of 10 mg/L. With most active infections and inflammatory processes, C-reactive protein levels are above 100 mg/L. Under these circumstances, the CRP test is used to follow the trend. Declining CRP levels are a sign that inflammation is decreasing. 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 such well-recognized risk factors as high blood pressure or high cholesterol, whether or not they smoke, their weight and their risk of diabetes. In addition to such standard measures for reducing the risk of cardiovascular disease as exercise, keeping weight under control, practicing stress reduction techniques and getting adequate sleep, Dr. Weil recommends that people with these 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 (statin) drugs used to lower LDL cholesterol to also lower levels of C-reactive protein. In addition, they will typically recommend exercise and weight loss where appropriate, since both can help lower CRP. 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 - quit smoking, watch your diet (particularly avoid foods that predominantly consist of flour and/or sugar), and get regular exercise. A recent study at Johns Hopkins showed that as fitness levels decline, CRP levels go up. The researchers weren't sure if poor fitness leads to an increase in CRP or vice versa, but exercise is an important part of maintaining heart health in any case.