What does having a result of 21.1 on a C-reactive protein test mean?

General responses to selected questions from Joel Braunstein, MD, of Johns Hopkins University and Joseph Toscano, MD.

Question:

What does having a result of 21.1 on a C-reactive protein test mean?

Answer:

Thank you for asking such an important question, which, I am sure, occupies the minds of many other individuals also reading this column. C-reactive protein is a molecule found inside the bloodstream. It is manufactured by the liver in response to tissue injury or inflammation, which may occur as a result of infection or other condition that stimulates the immune system. Based upon what I've told you thus far, you may be wondering what C-reactive protein has to do with the cardiovascular system.

Over the last decade, our understanding of the process of atherosclerosis (hardening of the arteries) has fundamentally evolved - formerly, we presumed atherosclerosis was primarily due to abnormal cholesterol deposition in the walls lining blood vessels. Over time, this progressive deposition would lead to progressive narrowing of the arteries and ultimately lead to the well-recognized clinical manifestations of cardiovascular disease such as heart attack and stroke. New insight into atherosclerosis now tells us that we grossly underestimated the complexity of this process. Part of this new knowledge recognizes that inflammation is among the most essential mediators of atherosclerosis. Inflammation plays a vital role in nearly every stage of development of atherosclerosis, from the earliest beginnings of silent heart disease to the most acute moments of a heart attack. Because C-reactive circulates in the bloodstream and its levels are an indicator of the amount of inflammation that occurs in the body at any given time, medical researchers have increasingly studied it as a potential marker of the severity and acuity of atherosclerotic heart disease. The results of these studies have been dramatic. C-reactive protein is a very strong predictor for the development of future cardiovascular events like heart attack, stroke, and peripheral vascular disease. C-reactive protein also closely correlates with other cardiovascular risk factors like smoking, obesity, and type 2 diabetes mellitus. What remains unknown is whether C-reactive protein is, in and of itself, involved with the inflammation of atherosclerosis or merely just a marker of the process. In addition, there is some controversy about how much additional cardiovascular risk information elevated C-reactive protein levels offer over more conventional risk factors like high blood pressure or cholesterol, diabetes, obesity, smoking, smoking, and family history of heart disease.

The risk scale for C-reactive protein is generally regarded as: less than 1 mg/L is low risk, 1 to 3 mg/L is average risk, and more than 3 mg/L is high risk. These values, however, should be considered in the context of your other risk factors for cardiovascular disease, including your age and gender; and before ascribing a high C-reactive protein level to any form of atherosclerosis, it is important to rule out other potential causes for elevated levels.

What to do for individuals who have elevated C-reactive protein levels is another debated issue. In general, you should discuss your need for and type of treatment with your physician. Individuals who are at high risk for future cardiovascular events should ensure that their other risk factors are optimally controlled, frequently with medications and through healthy lifestyle habits. Aspirin is also frequently recommended in the absence of contraindications, since aspirin reduces both inflammation and one's propensity to form blood clots.

If your doctor determines that you have only an intermediate cardiovascular risk based on a review of your other risk factors, he/she may decide that you could benefit from taking statins, which are a cholesterol-lowering agent and have been shown to protect against the development of future heart disease among individuals with high C-reactive protein levels, but normal or near-normal cholesterol levels. If you fall into a low risk category, and only have a high C-reactive protein level without other risk factors, aspirin may be your only recommended treatment.

Ultimately, it is important to carefully discuss the meaning of your high C-reactive protein level with your physician. Together, you should be able to design a strategy that effectively protects you from cardiovascular disease in your years to come.