What is hs-CRP? A guide to the inflammation marker

CRP and hs-CRP are the same protein

C-reactive protein rises when the body is dealing with inflammation, from infection to injury to chronic disease. MedlinePlus explains that the standard CRP test shows how much inflammation is present, while the high-sensitivity version detects very small increases and is used to estimate heart disease risk.

What hs-CRP cannot do is tell you where the inflammation is or why it is there. It is a smoke alarm, not a map.

Why inflammation matters for the heart

Atherosclerosis, the buildup of plaque in arteries, is partly an inflammatory process. People with persistently raised low-grade inflammation have, on average, a higher risk of heart attack and stroke even when cholesterol looks acceptable. That is why hs-CRP can help refine risk for someone in a gray zone.

It is not a cause in itself, and lowering it directly has not been shown to be the point. It is best treated as one more piece of evidence about overall risk.

What raises it besides heart disease

A long list of everyday factors can push hs-CRP up, which is why timing and context are crucial.

• A recent cold, flu or other infection
• Intense exercise in the previous day or two
• Injury, dental work or gum disease
• Excess abdominal fat
• Smoking and polluted air
• Poor sleep, insomnia and depression
• Menopausal hormone therapy, particularly oral estrogen
• Autoimmune and inflammatory conditions such as rheumatoid arthritis or inflammatory bowel disease

How the numbers are commonly read

Commonly used bands for cardiovascular purposes are below 1 mg/L (lower), 1 to 3 mg/L (average) and above 3 mg/L (higher). The 2018 ACC/AHA cholesterol guideline lists a persistently elevated hs-CRP of 2.0 mg/L or more as a risk-enhancing factor that can tip a borderline or intermediate-risk person toward statin therapy.

A result above about 10 mg/L generally signals an acute infection or inflammatory process rather than cardiovascular risk and should be repeated once that has settled. Check the units: MedlinePlus reports CRP in mg/dL, and 1 mg/dL equals 10 mg/L.

One result is never enough

Because so many things move hs-CRP, a single value is unreliable. A common approach is to repeat the test at least two weeks later, at a time when you are well and have not just done a hard workout, and to use the lower or average of the two. A level that is raised on both occasions carries more weight.

Where it fits in risk assessment

hs-CRP is an adjunct, not a primary risk factor. The U.S. Preventive Services Task Force concluded that the evidence is insufficient to recommend adding hs-CRP to traditional risk assessment for everyone. In practice, clinicians use it selectively, alongside age, blood pressure, cholesterol or ApoB, diabetes status, smoking, family history and sometimes a coronary calcium score.

A high hs-CRP in someone otherwise at low risk is a reason to look for an inflammatory cause and to review lifestyle, not to start treatment on that basis alone.

What brings it down

The same habits that lower heart risk tend to lower hs-CRP.

• Losing abdominal fat
• Regular moderate exercise
• Quitting smoking
• Improving sleep, including treating sleep apnea
• Treating gum disease and other chronic inflammation
• Statins, when indicated for cholesterol, also lower CRP

Preparing for the test

You do not usually need to fast for hs-CRP, although it is often drawn with other tests that do require fasting. To get a result that reflects your baseline, avoid testing within about two weeks of a cold, infection, injury or dental procedure, and skip strenuous exercise for a day or two beforehand. Tell your clinician about medicines and supplements, including NSAIDs, aspirin, statins and hormone therapy, since several can influence CRP.

Supplements and HealifyMD testing

Many supplements are marketed as anti-inflammatory, but none has strong evidence for lowering hs-CRP in a way that improves outcomes. With HealifyMD, a licensed clinician can include hs-CRP in your workup when it would help interpret risk, and will read it alongside your other results. The Comprehensive Lab Panel is $199, confirmed at your eligibility review.