How to track your hs-CRP over time

High-sensitivity CRP is the inflammation test that gets ordered next to a cholesterol panel. It is meant to say something about heart risk, and it is one of the noisiest numbers you will ever have drawn. A cold, a hard workout, or a pulled muscle can move it more than years of slow change. That makes a single hs-CRP close to useless on its own and a run of them quite useful, as long as you know which results to set aside.

What hs-CRP measures

C-reactive protein (CRP) is made by the liver in response to inflammation. It is an acute-phase protein, which means it reacts fast and by a lot. In their review of CRP, Pepys and Hirschfield describe it rising above 5 mg/L within about 6 hours of a trigger such as an infection or an injury, peaking around 48 hours, and climbing as much as 10,000-fold in severe cases. Its half-life in the blood is about 19 hours, and it is not affected by meals or the time of day. Outside acute illness, each person tends to sit at a fairly stable level of their own.

hs-CRP and standard CRP

There is only one protein. The two tests differ in the range they are built to measure and the question they answer:

• Standard CRP is used to look for and follow infection and inflammatory disease, where values run high. It is often reported in mg/dL.
• High-sensitivity CRP (hs-CRP) uses an assay that can measure very small amounts accurately. It is used to estimate cardiovascular risk, where the differences that matter are between 1 and 3 mg/L. MedlinePlus describes it as measuring “very tiny increases” in CRP.

A standard CRP of “normal” tells you there is no major inflammation. It does not tell you which hs-CRP risk group you are in. If your history has both, chart them as two separate tests.

The numbers on the report

The 2003 statement from the CDC and the American Heart Association, which set out how hs-CRP should be used, says results should be expressed as mg/L only. Many labs follow that. Standard CRP, though, is often reported in mg/dL, and some labs use mg/dL for hs-CRP too.

The two units differ by a factor of 10:

mg/L = mg/dL × 10

This is the most common way an hs-CRP chart goes wrong. A result of 0.2 mg/dL plotted next to results in mg/L looks like a dramatic improvement, when it is the same 2 mg/L. Check the unit on every result before you compare them. The lab unit converter has the factor for CRP and most other common tests.

Risk categories

The CDC/AHA statement set three groups, which correspond roughly to thirds of the adult population:

The current U.S. cholesterol guideline uses a different line. The 2026 ACC/AHA dyslipidemia guideline, which replaced the 2018 cholesterol guideline in March, lists an hs-CRP of 2 mg/L or higher on more than one occasion, if it was measured, as a risk-enhancing factor. The 2018 guideline used the same 2.0 mg/L cutoff. A risk enhancer does not mean you need treatment. It is one of several factors that can tip a borderline decision about a statin. The guideline treats hs-CRP as a selective test for when the usual risk estimate is uncertain. How to track your cholesterol over time covers the rest of that picture.

The 2 mg/L cutoff also has a trial behind it. JUPITER, described below, enrolled people with hs-CRP of 2.0 mg/L or higher.

How often it is tested

hs-CRP has no routine schedule. The CDC/AHA statement recommended against screening the whole adult population with it. It suggested hs-CRP for people at intermediate risk, at their clinician’s discretion, to help decide on further testing or treatment.

That position is under debate. In September 2025, an ACC scientific statement on inflammation and cardiovascular disease argued that guidelines should move to broad hs-CRP screening, together with LDL cholesterol, for people with and without heart disease. A scientific statement is not a guideline. The 2026 dyslipidemia guideline, published six months later, still uses hs-CRP selectively.

The part of the 2003 statement that matters most for tracking is how to measure it:

• Twice, about two weeks apart, and averaged. Fasting is not needed.
• When you are well. The statement calls for testing “in metabolically stable patients” without an obvious infection or inflammation.
• Results above 10 mg/L set aside. A value that high should prompt a look for an infection or inflammation. The statement says that result should be discarded and the test repeated in two weeks.

The 2026 guideline’s “more than one occasion” points the same way. One result is a starting point, not an answer.

What counts as a real change

hs-CRP varies a great deal within the same person. A 2024 systematic review of studies that measured it repeatedly found a median within-person variation of about 44 percent, with individual studies ranging from 27 to 76 percent. The authors note the estimates come from small studies, but all of them point to a test that moves a lot on its own. For comparison, the variation for TSH, itself a jumpy test, is about 18 percent.

In practice:

• A result of 1.4 followed by 2.3 is within ordinary noise. Both are in the same broad range, and the change would not be surprising with nothing different.
• A category on one result is weak. A single 3.2 that sits next to 1.8 and 2.1 says less than three results around 3.5.
• Look at the average and the spread. A cluster of results, taken when you were well, describes your level better than any one of them.
• Anything above 10 is a different question. It reflects something acute, and it belongs in your history as a note, not as part of your baseline.

When you compare before and after a change, such as starting a statin or losing weight, compare averages of two or more results on each side if you can. Did the medication actually do anything? covers reading a before-and-after fairly.

Things that move hs-CRP

Most of these are reasons to add a note to a result, not to doubt the lab.

• Infection, injury, surgery, and dental work. The classic causes. CRP rises within hours and falls with a half-life of about a day once the trigger is gone. A result drawn while you are getting over a cold is not your baseline.
• Hard exercise. In a study of 51 marathon runners, hs-CRP rose from 0.88 mg/L before the race to 11.5 mg/L the next day. Leave a few days between a long race or heavy training block and a draw.
• Body weight. In a large U.S. survey, Visser and colleagues found that obese adults were much more likely to have elevated CRP than normal-weight adults, with an odds ratio of about 2 in men and 6 in women. A big change in weight is worth a note next to the results that follow it.
• Smoking, poor sleep, and depression are all linked to higher CRP. MedlinePlus also notes that females often run slightly higher than males.
• Oral estrogen. In a randomized trial of 196 postmenopausal women, oral estrogen raised CRP over six months, while estrogen through the skin had no effect compared with placebo. The CDC/AHA statement noted that it is not known whether a rise caused this way reflects higher heart risk. If you start or stop oral estrogen, your hs-CRP may step up or down for that reason.
• Pregnancy. In a study of 100 healthy pregnancies, median CRP was 2.39 mg/L in the first trimester and 4.12 mg/L in the third, without infection. Pregnancy results do not belong in the same baseline as the rest.
• Your cycle. In the BioCycle study, CRP was about 1.6 times higher during a period than at ovulation, and more women were above 3 mg/L during their period. Your cycle shows up in your labs covers that study and suggests drawing at a similar point in the cycle each time.
• Statins. In the JUPITER trial, rosuvastatin lowered LDL cholesterol by 50 percent and hs-CRP by 37 percent in people who started with an hs-CRP of 2.0 mg/L or higher. If you started a statin, expect hs-CRP to fall along with LDL, and read the results that follow with that in mind.
• Chronic inflammatory conditions, such as rheumatoid arthritis or inflammatory bowel disease. A flare raises CRP for reasons unrelated to heart risk.

CRP also affects how other tests read. Ferritin rises with inflammation, so a ferritin drawn while your CRP was high can look better than your iron stores really are. How to track your ferritin over time explains why CRP is often ordered next to it.

What to record with each result

For each hs-CRP, keep:

hs-CRP appears on reports under many names: hs-CRP, HS CRP, High Sensitivity CRP, CRP High Sensitivity, and C-Reactive Protein, Cardiac among them. Pick one name and use it everywhere, or your history will split into short, separate lines.

Charting it

A few choices make an hs-CRP chart honest:

• Convert every result to mg/L first. A single mg/dL value on a mg/L chart looks like a tenfold drop.
• Draw lines at 1, 2, and 3 mg/L, or at whatever cutoff your clinician uses. A lab range printed as a single upper limit says little about which risk group you are in.
• Use a log scale if your results range widely, for example from 0.4 to 12. On a plain scale, everything under 3 looks flat.
• Flag anything above 10. Keep it on the chart with a note about the illness or injury behind it, and leave it out when you work out your average.
• Mark statin and estrogen starts, and any big change in weight or training.
• Keep standard CRP on its own chart. It answers a different question.
• Space points by date. A pair two weeks apart and a gap of three years should not look evenly spaced.

How to track your lab results over time has the general method for any test.

Tracking hs-CRP in HealthViewer

HealthViewer is a lab results tracker that runs on your own computer. It imports hs-CRP from lab report PDFs, MyChart downloads, and direct connections to your health system. It keeps hs-CRP and standard CRP as two separate tests on purpose, because their ranges answer different questions. Names such as hs-CRP, HS CRP, High Sensitivity CRP, and CRP High Sensitivity file under hsCRP, and results your health system sends under the standard code for high-sensitivity CRP file there too. CRP and C-Reactive Protein, and the standard CRP code, file under CRP. A name the app does not recognize, such as “C-Reactive Protein, Cardiac”, arrives as its own test. Combine it with your other hs-CRP results using Merge… in the Test Catalog.

Results in mg/L and mg/dL are converted so they share one chart, and the chart title shows the unit in use. That takes care of the factor-of-10 trap, as long as each result was imported with its unit.

In Trends, the Inflammation tag pulls together CRP, hsCRP, ESR, and homocysteine. hs-CRP is not in the Heart tag by default, but you can add it in the Test Catalog so it appears with your lipids. The overlay view puts hs-CRP and LDL on one chart, and medication markers show where a statin or oral estrogen started or stopped. Set a custom range in the Test Catalog, such as below 2 mg/L, and the chart shades that band instead of the lab’s.

Add a journal entry for a cold, a race, or dental work, then turn on Show journal to see it next to the spike it explains. If you track your cycle in Cycle with lab context turned on, each result shows the cycle day it was drawn on, and the Cycle button in Trends shades your periods behind the chart.

Everything stays in an encrypted file on your computer, with no account and no cloud service. Getting Started walks through the first import.

This post is general information, not medical advice. Talk to your clinician about what your hs-CRP means for you and before starting or changing any treatment.