ESR vs hsCRP: Key Differences Explained
ESR measures how fast red blood cells settle in mm/hr and moves over days to weeks. hsCRP measures C-reactive protein in mg/L and reacts within hours.
ESR and hsCRP are both blood tests for inflammation, but they measure different things at different speeds. ESR (erythrocyte sedimentation rate) measures how far red blood cells settle in a tube in one hour, an indirect effect of inflammatory proteins. hsCRP measures one specific protein, C-reactive protein, with a high-sensitivity assay.
Neither test identifies the cause or location of inflammation. Results need to be interpreted with symptoms, medical history, and the reporting laboratory’s reference information.
What is ESR?
ESR is an inexpensive, widely available test used to evaluate and monitor inflammatory conditions. It moves slowly, rising and falling over days to weeks, which gives it a long-window view of inflammatory activity. Inflammatory proteins make red blood cells clump and settle faster, so a higher sedimentation rate, reported in millimeters per hour (mm/hr), suggests inflammation.
Because the test reads a physical settling rate rather than an inflammatory protein itself, it is an indirect marker. Anemia, age, sex, pregnancy, and immunoglobulin levels all change how fast red cells settle, which makes ESR less specific than CRP-based tests.
What is hsCRP?
hsCRP measures C-reactive protein, which the liver produces in response to inflammation, reported in milligrams per liter (mg/L). CRP rises within hours of an inflammatory stimulus, peaks around two days, and falls quickly once the trigger resolves.
The high-sensitivity assay measures low CRP concentrations, which is what makes the result usable for cardiovascular-risk context. Current prevention guidance treats a persistent result of 2 mg/L or higher as a risk-enhancing factor. A result above 10 mg/L usually reflects acute inflammation rather than a cardiovascular-risk baseline, so retest when you are feeling well.
If you are weighing hsCRP against the standard CRP assay instead, see CRP vs hsCRP.
ESR versus hsCRP
Question | ESR | hsCRP |
|---|---|---|
What does it measure? | How far red blood cells settle in a tube in one hour | The concentration of C-reactive protein in blood |
Units | mm/hr | mg/L |
Direct or indirect? | Indirect: a physical settling rate influenced by inflammatory proteins | Direct: one specific protein the liver produces during inflammation |
How fast does it change? | Slowly, over days to weeks | Within hours, peaking around two days, then falling quickly |
What else can shift the result? | Anemia, age, sex, pregnancy, and immunoglobulin levels | Estrogen-containing medicines raise it and statins lower it, independent of inflammation |
Common clinical role | Supporting the evaluation and monitoring of inflammatory conditions | Answering the low-level, cardiovascular-risk question; broader inflammation monitoring uses standard CRP or ESR |
Which test should you choose?
It depends on the question you are answering.
- For cardiovascular-risk context with no active illness, hsCRP is the assay designed for that question.
- For evaluating or monitoring an inflammatory condition, your doctor may order either test, and often both.
Ordering both is common because the two move at different speeds. hsCRP flags new inflammation early, and ESR can stay elevated after CRP has returned to normal, which helps distinguish new inflammation from inflammation that is resolving.
Frequently asked questions
- Do you need to fast? No. You don’t need to fast for ESR or hsCRP on its own. If other tests are collected at the same visit, follow the instructions on your order.
- Can medicines or supplements affect the results? Yes, some can affect either measurement or its interpretation. Do not stop a prescription medicine because of a result without speaking with your prescribing clinician.
- Does a high hsCRP result mean heart disease is present? No. hsCRP adds information to an overall cardiovascular-risk assessment, but it does not diagnose cardiovascular disease.
Order the hsCRP test
If you want the high-sensitivity CRP measurement, view the individual hs-CRP test for current member and non-member pricing, availability in your state, and checkout. For prices across labs, see the hs-CRP test cost comparison. For how testing works step by step, see the hs-CRP blood test guide.
Sources
- MedlinePlus: Erythrocyte Sedimentation Rate (ESR) test
- MedlinePlus: C-Reactive Protein test
- American Heart Association: hsCRP and cardiovascular-risk assessment
Medical disclaimer
This comparison is for informational purposes only and does not provide medical advice, diagnosis, or treatment. It is not a substitute for care tailored to your health history and symptoms.
