What Is hs-CRP (High-Sensitivity C-Reactive Protein)?

C-reactive protein is made by the liver in response to signals released when tissue is inflamed. Inflammation is the body's standard reaction to infection, injury, and irritation, and CRP is one of the substances that rises with it. It has been measured in laboratories for decades.

The high-sensitivity version measures that identical protein. The difference sits in the method, not the target. You may see it written hs-CRP, high-sensitivity CRP, cardiac CRP, or CRP-hs on an order form or a result. All of these refer to the same measurement, and none of them is a separate marker in the body.

The standard CRP assay was designed for a different job. Infections, injuries, surgery, and flares of inflammatory disease push CRP up sharply, and a conventional assay reads those large movements perfectly well. What it cannot do is resolve the small differences that sit near the bottom of its range — for the standard method, a modestly elevated result and a genuinely quiet one can be hard to tell apart.

That bottom of the range turned out to matter. Research linked small, persistent differences in CRP among people who felt entirely well to differences in cardiovascular risk over time. Reading those differences reliably required an assay with finer resolution at low concentrations, and that is what the high-sensitivity method provides. So "high-sensitivity" is a statement about measurement precision, not about a more sensitive form of inflammation.

Standard CRP is the one used when inflammation is expected to be substantial and the question is how much: an active infection, recovery after surgery, or following the course of a condition such as rheumatoid arthritis or inflammatory bowel disease. In those situations the added precision at the low end contributes nothing, because the result is nowhere near the low end.

hs-CRP is the one used when a person feels well and the question is whether a quiet, low-grade inflammatory signal is present. That is a cardiovascular risk conversation, usually held alongside cholesterol markers. The distinction has a practical edge: ordering standard CRP when the question was about low-grade inflammation can leave you with a result too coarse to answer it, so it is worth confirming which version a clinician wants before booking a draw.

CRP reflects inflammatory activity somewhere in the body. What it cannot do is say where. A dental infection, a sprained ankle, a flaring joint condition, and arterial inflammation can all lift the same marker, and the number carries no label identifying the source.

That non-specificity shapes how it is used. In a cardiovascular context, hs-CRP contributes an angle that cholesterol and particle-count markers do not cover, because it describes inflammatory tone rather than the fats being carried in the blood. It is one input into a risk picture that a clinician assembles from several sources, including blood pressure, family history, smoking status, and metabolic markers. On its own it settles nothing.

Recent illness is the biggest confounder. A cold, a stomach bug, a dental procedure, a cut that became infected, or surgery within the preceding weeks can lift the marker well above where it usually sits for that person, and the effect fades as recovery proceeds. That is why clinicians generally want the sample drawn during a stretch of good health.

Other everyday influences include intense or unaccustomed exercise in the days before a draw, poor sleep, smoking, body weight, pregnancy, and oral hormone preparations. Ongoing inflammatory conditions raise the baseline in a persistent way. Because a single reading can be thrown off by any of these, clinicians often prefer to look at more than one measurement taken a couple of weeks apart while a person is well, rather than acting on one figure.

This page does not describe what any particular result means. Interpretation depends on the assay, the surrounding markers, and a person's history, and belongs with the clinician reviewing it.

hs-CRP is commonly ordered with a lipid panel — LDL cholesterol, HDL cholesterol, and triglycerides — and increasingly with apolipoprotein B, which counts the cholesterol-carrying particles rather than the cholesterol they hold. Some clinicians add lipoprotein(a), which is largely inherited and worth knowing once.

Metabolic markers such as fasting glucose and hemoglobin A1c often appear on the same requisition, since metabolic and inflammatory patterns tend to travel together. Drawing them at one visit means the results describe the same moment, which makes the overall picture easier for a clinician to read.

hs-CRP is measured from a routine blood draw collected at a Quest patient service center. Fasting is not typically required for this marker on its own, though the lipid or glucose tests often ordered with it may have their own instructions, so follow whatever comes with your order.

Ordering through Celio Health includes the physician's order the test requires, so no separate appointment is needed and no insurance is billed. Results are emailed to you securely as a PDF and are meant to be reviewed with a clinician, who can weigh them against the rest of your picture.