After reading many article on the CRP blood test, I chose to create more of a unique page for this site. This is simply a review of Dr. Paul M. Ridker's article, C-Reactive Protein: A Simple Test to Help Predict Risk of Heart Attack and Stroke. This article was chosen because it was a comprehensive article on the subject of the CRP blood test, yet it was understandable. Please feel fee to read the full text for a more in-depth look, however, if you want the highlights . . . read on!
Even if you think you are heart-healthy, please pay attention to this fact! Out of the 1.5 million heart attacks and 600,000 strokes that occur each year, half of these strike otherwise healthy individuals. We all know that older age, obesity, diabetes, high blood pressure, and smoking all contribute to high C Reactive Protein levels and cardiovascular disease but so does genetics.
The American Heart Association and the Center for Disease Control and Prevention have both endorsed the use of the high-sensitivity CRP assays. The CRP blood test should not replace a cholesterol test but should be used in tandem with it. See the chart regarding low to high CRP levels.
Please remember that CRP levels can be inherited! Also, remember that high C Reactive Protein is a sign of inflammation and too much inflammation harms the blood vessels and cause atherosclerosis. Studies have found that blood markers are elevated in those who are at high risk for future cardiovascular disease and that the levels of CRP are highly predictive of heart disease in otherwise healthy individuals.
Figure 1. Cardiovascular event-free survival based on combined hs-CRP and LDL cholesterol measurements. Adapted from Ridker et al (N Engl J Med 2002;347:1557–1565).1
This is a very interesting piece of information. You should have both tests because these tests are independent of each other and measure different components of the disease process. Please look at the chart to the left for an interesting fact that might enlighten you on a pertinent fact.
Yes, it is obvious that low levels of both CRP and LDL (bad cholesterol) result in a low risk of cardiovascular disease, and high levels of each result in a high risk. However, take a look at the chart and notice that a person with low levels of LDL may think they are doing great heart-wise but if their CRP levels are high with low LDL, they are at a significantly higher risk of heart disease!
Without the CRP test, they would have never known!! The result, CRP is actually a stronger overall predictor of heart disease than is LDL cholesterol!
Since cholesterol is typically tested in the person's 30's, it would be wise to add the hs-CRP test to the cholesterol test. The best candidates for this test are those who are concerned about vascular risk and fall into the category of "intermediate risk". Why the category? Because those at very high risk are typically, overweight, smokers, and have high blood pressure. Those in the intermediate risk are much more likely to make a lifestyle change.
After viewing the chart on my page High C Reactive Protein,
please note that there are some additional facts to acknowledge. First,
if your levels are very high, such as above 10 mg/L, you should retake
the test in two to three weeks because it may have spiked due to an
infection. This is why Dr. Ridker advises to take the test when you are
Post menopausal women who take hormone replacement therapy (HRT), such as estrogen or estrogen plus progesterone tend to have elevated levels of CRP. This might make you think twice about taking HRT because no studies have shown HRT to decrease heart disease.
To summarize, the average CRP in middle-aged people is 1.5 mg/L. Around 25% of the US population have levels above 3.0 mg/L, which is the cut point indicating a high risk of heart disease. This is an inexpensive test and requires no fasting, so why would you not order this test?
1. Ridker, Paul, M. MD, MPH. "C-Reactive Protein A Simple Test to Help Predict Risk of Heart Attack and Stroke." Circulation AHA Journals. American Heart Association. Web.23 Mar 2013. <http://circ.ahajournals.org/content/108/12/e81.full>
2. Ridker PM, Rifai N, Rose L, et al. Comparison of C-reactive protein and low-density lipoprotein cholesterol levels in the prediction of first cardiovascular events. N Engl J Med. 2002; 347: 1557–1565.