The hs-CRP test measures C-reactive protein, a substance your liver releases when there is inflammation somewhere in the body. The "high-sensitivity" version can detect the very low levels seen in people who feel well. Persistently raised levels are linked to a higher risk of heart attack and stroke.
It is a useful extra piece of information, not a diagnosis. hs-CRP cannot show where inflammation is coming from or whether you have plaque, and a single result is easy to distort. Read it alongside your other risk factors.
Key takeaways
- hs-CRP measures low levels of C-reactive protein, a marker of inflammation somewhere in the body.
- Persistently raised levels are linked to higher heart attack and stroke risk, though the link is moderate.
- It cannot show where inflammation comes from or whether you have plaque.
- Illness, injury, inflammatory flares, excess body fat and smoking can push the number up, so a raised result is worth repeating.
- The test is not universally endorsed for screening and helps most when a treatment decision is uncertain.
What hs-CRP measures
C-reactive protein rises quickly and sharply when you have an infection or injury. That is the standard CRP test doctors use to track illness. The high-sensitivity test uses the same protein but measures much smaller amounts, in the range that reflects quiet, long-running inflammation.
That low-grade inflammation takes part in how plaque forms and becomes unstable in artery walls. Our article on inflammation and heart disease explains the biology. This one is about the test itself and how to read your number.
What the ranges mean
Results are reported in milligrams per liter (mg/L). The categories in common use trace back to a 2003 statement from the American Heart Association and the Centers for Disease Control and Prevention.
| hs-CRP result | Relative risk category | How to read it |
|---|---|---|
| Below 1 mg/L | Lower | Little sign of ongoing inflammation |
| 1 to 3 mg/L | Average | Neither reassuring nor alarming |
| Above 3 mg/L | Higher | Worth confirming with a repeat test and looking for a cause |
Values below 1, from 1 to 3, and above 3 mg/L indicate lower, average and higher relative cardiovascular risk.12
These are relative categories. They compare you with other people. They do not tell you your absolute chance of a heart attack, which depends far more on age, blood pressure, cholesterol, diabetes and smoking.
There is one more number to know. US cholesterol guidance has listed an hs-CRP of 2.0 mg/L or higher as a risk enhancer, a finding that can tip the balance toward treatment when your calculated risk sits in a gray zone.3
How much does a raised result matter? The link with heart risk is real but moderate. In a UK study of nearly 450,000 adults without known cardiovascular disease, people with hs-CRP above 3 mg/L had a 34% higher risk of a major cardiovascular event than those below 1 mg/L, after adjusting for other risk factors. People at 2 mg/L or above had a 22% higher risk than those below 2.4
The middle of the range is ordinary. The median level in that study was 1.32 mg/L. So a result of 1.5 is not a warning sign. It is close to the middle of the population.
What throws the result off
CRP responds to almost any inflammation, not just the kind linked to arteries. A single reading can be misleading if it was taken at the wrong time. Things that push it up include:
- A cold, flu, urinary infection, dental infection or any other recent illness
- An injury, surgery or a recent dental procedure
- A flare of an inflammatory condition such as rheumatoid arthritis, psoriasis or gout
- Excess body fat, particularly around the waist
- Smoking
If you were unwell around the time of the blood draw, tell your clinician. A result that is far above the usual range more likely reflects something acute than your long-term heart risk, and the sensible step is to repeat the test once you have recovered. It is reasonable to confirm any raised result with a second test before acting on it.
When the number is settled, it tends to stay put. In the UK study, repeat measurements taken about four years later in nearly 16,000 people showed long-term stability.4
What experts disagree about
You should know that hs-CRP is not universally endorsed for screening. In 2018 the US Preventive Services Task Force concluded that the evidence was insufficient to assess the balance of benefits and harms of adding hs-CRP to traditional risk assessment in adults without symptoms.5 Adding it improved risk prediction a little, but it was unclear whether that leads to fewer heart attacks.
Cardiology guidance has given the test a limited role. It is considered most appropriate in people without known heart disease when the decision to start treatment is uncertain.2
The practical reading is this: hs-CRP is most useful when a decision is uncertain and the result could change it. It is less useful as a stand-alone number with no plan attached.
What tends to lower hs-CRP
The measures with the best evidence are the same ones that lower heart risk generally.
- Weight loss. A review of 33 weight-loss studies found CRP fell by about 0.13 mg/L for each kilogram lost.6
- Exercise, diet and stopping smoking. Cardiologists treat these as the first steps for anyone with a raised result.
- Treating the source. A lingering infection, a poorly controlled inflammatory condition or insulin resistance can each keep CRP up. See our page on insulin resistance.
Medication is a separate question. In one large trial, statin treatment lowered the rate of first heart attack, stroke or cardiovascular death in people with hs-CRP above 2 mg/L whose LDL cholesterol was below 130 mg/dL.2 Whether that applies to you is a decision about your overall risk, made with your clinician, not something to settle from a CRP result alone.
hs-CRP in a Cardio Res-Q assessment
hs-CRP is part of the lab panel in both Cardio Res-Q assessments. The Comprehensive Assessment ($775) includes it with ApoB, Lp(a), homocysteine, insulin, glucose and A1c, the Cleveland Heart cardiac panel and Dr. Varano's clinical evaluation. The Enhanced Assessment ($999) adds a CIMT ultrasound and a coronary calcium score.
Your result is reviewed together with the rest of the panel, since inflammation means more when it sits beside a high ApoB or raised blood sugar. You fast for 10 to 12 hours before the blood draw. For the full sequence, read what to expect at your assessment, or go to the Cardio Res-Q program page to book.
Are You a Candidate for Cardio Res-Q?
Three quick questions about the risk factors we screen for. Your answers stay between you and the clinic.
Frequently asked questions
Is hs-CRP the same as a regular CRP test?
It measures the same protein with a more sensitive method. A standard CRP test is built to track large rises during infection or inflammatory disease. The high-sensitivity test reads the low range that relates to heart risk.
My hs-CRP is high. Does that mean I have heart disease?
No. It means there is inflammation somewhere, and the cause may have nothing to do with your arteries. A repeat test when you are well, plus a look at your other risk factors, tells you far more than one raised number.
Should I postpone the test if I have a cold?
Tell the clinic. An infection can raise CRP sharply and make the result hard to interpret, so it may make sense to wait until you have recovered or to plan a repeat.
Can a normal hs-CRP rule out heart risk?
No. Plenty of people with low inflammation have high cholesterol particles, high blood pressure or a strong family history. A low hs-CRP is one favorable sign, not an all-clear.
Related reading
This article is for general education and is not medical advice. Decisions about testing and medication should be made with your clinician. If you have chest pain or other symptoms of a heart attack, call 911.
