C-reactive Protein Test

Overview

The liver creates C-reactive protein (CRP), which circulates in the blood. CRP levels rise when the body experiences inflammation, making it an important indicator for several health conditions. A routine blood test measures CRP levels.

There is also a high-sensitivity version, called the hs-CRP test, which detects even slight increases in CRP and helps predict the risk of coronary artery disease.

Key Uses of CRP Testing:

Test type Purpose
CRP Detects inflammation
hs-CRP Heart risk analysis

Reasons for C-reactive Protein Tests

Doctors use a C-reactive protein (CRP) test for several important health reasons. When someone has symptoms that could signal infection or inflammation, a doctor may check their CRP levels. High CRP can point to conditions such as infections, rheumatoid arthritis, lupus, or inflammatory bowel disease (IBD).

Information About CRP Tests and Heart Health

CRP tests can also provide insight into potential heart disease. A specialized version, called the high-sensitivity CRP (hs-CRP) test, detects even small increases in inflammation. Research suggests that higher hs-CRP levels may be linked to a greater risk of heart problems, including heart attacks.

However, hs-CRP results are not specific to the heart. Elevated levels could be due to other infections or inflammatory conditions. Doctors usually recommend hs-CRP testing for people with a moderate risk of heart disease, based on health history, lab findings, and lifestyle factors.

Potential Side Effects

A C-reactive protein test has only minor risks. Possible issues include:

  • Temporary pain or bruising where the blood is drawn.
  • A rare chance of infection at the needle site.
  • Lightheadedness or fainting during or after the blood draw (less common).

Most people tolerate the test well and recover quickly without complications.

How You Get Ready

You usually do not need to fast or change your eating habits before a C-reactive protein test. However, you should avoid heavy exercise like running or lifting weights just before the test, as this can increase CRP levels for a short time.

Tell your healthcare professional about all medicines, even those bought without a prescription. Some medicines can change the results. If you are having more than one blood test, like a cholesterol check along with the CRP test, your doctor might ask you not to eat or drink for several hours.

How the Test Happens

A healthcare worker uses a needle to draw blood from a vein, often in the armโ€™s bend, during a CRP blood test. The process takes just a few minutes. The lab analyzes the blood, and you can usually carry on with your normal day right after. Only mild soreness or bruising might occur.

Findings

Labs usually provide C-reactive protein (CRP) test results in a few days. Medical professionals measure these results in milligrams per liter (mg/L). The value and context of the person being tested determine the meaning of the result. High-sensitivity CRP (hs-CRP) tests help check for low levels of inflammation linked to heart disease.

CRP Test Reference Table

CRP Level (mg/L) Risk Category
Less than 2.0 Lower risk of heart disease
2.0 or higher Higher risk of heart disease
8.0 or higher High, possible inflammation present
10.0 or higher Markedly elevated, further evaluation

Different labs may use different reference numbers, so a healthcare provider will interpret the result. A single CRP value may not provide enough information. Doctors often average two hs-CRP values, usually measured two weeks apart, to better assess heart disease risk.

Since CRP levels can change over time, this approach gives more accurate information. A higher CRP test result does not identify the cause of inflammation. It only indicates likely inflammation somewhere in the body. Other health problems, such as infections or injuries, can raise CRP levels.

Healthcare professionals consider CRP alongside other test results and risk factors before giving advice. They may suggest additional tests or changes to daily habits if they have concerns about heart disease.


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