C-Reactive Protein
(CRP)

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Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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What is C-reactive protein (CRP)?

C-reactive protein (CRP) is a blood test marker for inflammation in the body. CRP is produced in the liver and its level is measured by testing the blood.

CRP is classified as an acute phase reactant, which means that its levels will rise in response to inflammation. Other common acute phase reactants include the erythrocyte sedimentation rate (ESR) and blood platelet count.

What are the main causes of an elevated C-reactive protein?

In general, the main causes of increased CRP and other markers of inflammation are:

• burns,
  
  
• trauma,
  
  
• infections,
  
  
• inflammation,
  
  
• active inflammatory arthritis, and
  
  
• certain cancers.

Is there a link between C-reactive protein (CRP) and cardiovascular disease risk?

The elevation of CRP has also been recently linked to atherosclerosis and heart disease. Atherosclerosis, or cholesterol plaquing of the arteries, is known to have an inflammatory component that is thought to cause the rise in CRP levels in the blood. Atherosclerosis is also felt to be affected by age and other cardiovascular risk factors including diabetes mellitus, high cholesterol, high blood pressure, and cigarette smoking.

In atherosclerosis, the blood vessel wall becomes injured. This injury acts as focus of inflammation and leads to the formation of plaques in the blood vessel walls. The plaques typically contain blood cells of inflammation, cholesterol deposits, and debris from the injured cells in the blood vessel lining. The accumulation of these elements leads to narrowing of the wall of the blood vessel. The blood vessel narrowing can hinder the blood flow and the plaque can rupture and flake off of the blood vessel wall causing blockage and leading to strokes and heart attacks.

The burden of plaques in the body can be proportional to the degree of CRP elevation in persons with atherosclerosis. Atherosclerotic plaques can exist in different stages throughout the body.