C-Reactive Protein- High Sensitivity hs-CRP

This test measures high-sensitivity CRP, a marker of inflammation.

What is High-Sensitivity CRP?

The high-sensitivity C-reactive protein (hs-CRP) test is a blood test that measures the level of hs-CRP in the blood. CRP is a protein produced by the liver that increases in response to inflammation in the body. The hs-CRP test is a more sensitive version of the CRP test, meaning it can detect lower levels of CRP in the blood.

High levels of hs-CRP in the blood may be a sign of inflammation in the body, which can be caused by various conditions, such as infections, injuries, autoimmune disorders, and certain chronic diseases. The hs-CRP test is often used to help evaluate a person's risk of developing cardiovascular disease, as high levels of hs-CRP have been associated with an increased risk of heart attack and stroke. A healthcare provider usually orders the hs-CRP test as part of a routine health check-up or if they suspect a person may have inflammation in the body.

Defining hs-CRP

To illustrate the difference between CRP and hs-CRP, traditional testing measures CRP (quantitative) within the range of 10 to 1,000 mg/L, whereas hs-CRP values range from 0.5 to 10 mg/L. In simpler terms, hs-CRP measures trace amounts of CRP in the blood. Hs-CRP is the analyte of choice for cardiovascular risk assessment.

High-Sensitivity CRP Reference Ranges

Jellinger PS et al. Endocr Pract. 2017;23(Suppl 2):1-87.

For ages >17 years

Role of hs-CRP

People who are at a high risk for cardiovascular events, including those who are candidates for secondary prevention, are likely already taking or can get statin or aspirin therapy, which is known to lower hs-CRP and improve overall cardiovascular outcomes. People have said that hs-CRP may be useful as an independent marker of prognosis for recurrent events like death, myocardial infarction, and restenosis in patients with stable coronary disease, acute coronary syndromes, or who have had percutaneous coronary intervention. This information could be especially helpful when talking to patients about how important it is to follow the instructions for secondary preventive interventions.  Hs-CRP may also be helpful for people who don't have any risk factors for cardiovascular disease.

These people are called low cardiovascular risk patients, and they would not have been found to be good candidates for primary prevention therapy without Hs-CRP. At the moment, however, there is no evidence that using a hs-CRP >2 mg/L to predict cardiovascular risk on its own is clinically useful or cost-effective. In fact, the AHA says that all adults shouldn't have their hs-CRP levels checked as a way to figure out their risk of heart disease. So, hs-CRP will have the biggest effect on people who are at an intermediate risk for cardiovascular events and don't know if they should start primary preventive therapy.

People with a hs-CRP level of more than 2 mg/L and other cardiovascular risk factors should be tested again in two weeks to rule out an acute inflammatory response. This is because people with a hs-CRP level of more than 2 mg/L and other cardiovascular risk factors are considered to have intermediate cardiovascular risk. Patients with a high hs-CRP level of >10 mg/L that can't be explained after multiple tests should be checked for noncardiovascular causes, such as an infection, active arthritis, or another illness. If the hs-CRP level stays high, the patient may be reclassified as having a high cardiovascular risk, which would be a good reason to start treatment for primary cardiovascular prevention. It's important to remember that the best ways to lower CRP are also the best ways to lower the risk of heart disease. These include diet, exercise, controlling blood pressure, and quitting smoking.

Reference:

The Application of High-Sensitivity C-Reactive Protein in Clinical Practice: A 2015 Update