hs-CRP, or high-sensitivity C-reactive protein, is a blood test that measures the same liver-made inflammation protein as an ordinary CRP test, but with an assay sensitive enough to read the low concentrations that matter for long-term cardiovascular risk. Ordinary CRP is used to spot obvious inflammation: infection, injury, a flaring autoimmune disease. The high-sensitivity version detects the quiet, low-grade inflammation that sits in the background for years without symptoms, which is what ties the test to aging rather than to acute illness.
What it measures
The liver makes C-reactive protein in response to inflammatory signaling, largely interleukin-6 released by immune cells and by fat tissue. Levels climb within hours of an acute stimulus and fall back over days once the trigger clears. The test is a standard venous blood draw, usually reported in milligrams per liter (mg/L); some US labs report milligrams per deciliter, where 1 mg/dL equals 10 mg/L. No separate molecule is involved: C-reactive protein (CRP) and hs-CRP are the same protein read on assays with different working ranges.
The number is non-specific. It says inflammation is present, not where it comes from, so gum disease, a recent cold, a hard unaccustomed workout and visceral fat all push it the same way. Because a single reading bounces around, the usual practice is two measurements at least two weeks apart while you are well, read alongside the rest of the panel and any other Inflammatory markers a clinician orders.
Typical values
The bands most widely quoted come from a joint American Heart Association and CDC scientific statement, and they are risk categories for adults rather than a normal range.
| hs-CRP (mg/L) | Usual reading |
|---|---|
| Below 1 | Lower relative cardiovascular risk |
| 1 to 3 | Average relative risk |
| Above 3 | Higher relative risk |
| Above 10 | Suggests acute inflammation or infection; repeat once you have recovered |
Treat these as convention, not physiology. The distribution differs by sex, age, body weight and ancestry, and assays are not perfectly interchangeable, so the units and reference interval on your own report govern. Some guidelines and trials have instead used a threshold near 2 mg/L to define an inflammatory risk group. The categories and retest rules are set out in more detail in hs-CRP — high-sensitivity C-reactive protein.
Why it matters for longevity
In large observational cohorts, higher hs-CRP is associated with more heart attacks and strokes and with higher all-cause mortality; in older adults it also tracks with frailty and physical and cognitive decline. It is one of the nine routine blood measures behind the PhenoAge score, which is why an inflammation marker turns up inside blood-based estimates of biological age.
The causal story is more careful than the association. Genetic studies that vary CRP levels directly suggest the protein is a messenger rather than the culprit, so lowering the number for its own sake is not the goal. What trials support is treating the inflammation it reports: in JUPITER a statin reduced cardiovascular events in people whose LDL was not high but whose hs-CRP was, and in CANTOS an antibody against interleukin-1 beta reduced recurrent events while leaving cholesterol untouched.
What changes it
The largest everyday lever is body fat, especially around the abdomen: losing excess weight lowers levels and gaining raises them. Stopping smoking helps. Regular aerobic and strength training are associated with lower values, partly through fat loss, though a single hard session raises the marker for a few days. Short sleep, chronic stress, untreated gum disease and any active infection push it up; a Mediterranean-style, fiber-rich pattern is associated with lower values.
Medication matters too. Statins lower hs-CRP alongside cholesterol, and drugs for inflammatory disease lower it substantially. Estrogen-containing contraceptives and oral hormone therapy raise measured levels without implying more vascular inflammation. Recent surgery, injury or vaccination raise it transiently, which is the main reason to postpone testing. Part of the variation is simply inherited.
Related reading
- Chronic Inflammation and Aging: Inflammaging
- Which Blood Tests Reflect Aging and How to Read Them
- What Biological Age Is and How to Measure It
Disclaimer. This article is for information only and does not replace medical advice. Talk to a qualified clinician before changing anything about your health.