What Is an hs-CRP Test
The hs-CRP test is a blood test that measures levels of high-sensitivity C-reactive protein, a substance the liver produces when inflammation is present in the body. Unlike a standard CRP test, the high-sensitivity version can detect very low concentrations of the protein, which makes it useful for assessing cardiovascular risk even when inflammation is subtle.
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Why Doctors Order the Test
Physicians use the hs-CRP test to help evaluate a person's risk of heart disease, heart attack, or stroke. Inflammation in the arteries contributes to the buildup of plaque, and elevated hs-CRP levels may signal that this process is active. The test is not a standalone diagnostic tool but provides information that complements other risk markers such as cholesterol, blood pressure, and blood sugar.
When It Is Recommended
A doctor may recommend an hs-CRP test for people who have an intermediate risk of cardiovascular disease based on traditional risk factors. It is also used to monitor inflammation in conditions such as rheumatoid arthritis, lupus, or inflammatory bowel disease, though different lab ranges often apply for those contexts compared with cardiac risk assessment.
Understanding the Results
Results are reported in milligrams per liter of blood. Generally, a reading below 1.0 mg/L suggests low cardiovascular risk, a reading between 1.0 and 3.0 mg/L indicates average risk, and a reading above 3.0 mg/L signals high risk. However, a single elevated result does not confirm heart disease, because infections, injuries, and other inflammatory conditions can also raise CRP temporarily.
What the Test Cannot Do
The hs-CRP test does not identify the source of inflammation, nor does it replace standard heart disease screening. It works best when interpreted alongside a full clinical picture, including family history, lifestyle factors, and other lab work.
Preparing for the Test
Fasting is not usually required, but patients should tell their doctor about any medications, supplements, or recent illnesses that could affect inflammation levels. The test itself involves a simple blood draw and carries minimal risk.