Lab tests
CRP and ESR (inflammation marker) explainer
CRP and ESR are both called inflammation markers, but they are measured in completely different ways and reported in different units, and CRP comes in a standard and a high-sensitivity version. Add your report below to see which test you had and how each value sits against the range printed beside it.
Explain your CRP and ESR (inflammation marker)
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What you get
- CRP and ESR on separate rows, with a short note on how each is measured.
- Standard CRP told apart from high-sensitivity CRP (hs-CRP) when the report names the method.
- Units such as mg/L, mg/dL and mm/hr written out.
- Questions to ask about what the test was looking for.
Lines you may see on an inflammation marker report
- CRP (C-reactive protein)A protein made by the liver that rises in the blood when there is inflammation in the body
- hs-CRP (high-sensitivity CRP)The same protein measured with a method that can read much lower levels
- ESR (erythrocyte sedimentation rate), also called sed rateHow far red blood cells settle in an upright tube in one hour
- mm/hrMillimetres per hour, the unit for ESR
- WestergrenThe name of a common method for measuring ESR
- Plasma viscosityA measure of how thick the liquid part of the blood is, which some laboratories use in place of ESR
What this tool cannot tell you
These tests are non-specific. They can show that inflammation is present somewhere but not where it is or what is behind it, and they do not always move together. ESR ranges usually depend on age and sex, and CRP may be printed in mg/L or mg/dL, units that differ by a factor of ten, so figures from different reports are easy to misread. MedicDecode explains the lines on your report and leaves the cause, if there is one, to your clinician.
Common questions
Why were both CRP and ESR ordered?
They reflect inflammation in different ways and change at different speeds, so clinicians sometimes request both. The report will not usually say why; the person who ordered the tests can.
Is hs-CRP a different substance from CRP?
No. It is the same protein. High-sensitivity describes the laboratory method, which can measure lower concentrations than the standard test.
My CRP is printed as less than a number, such as <5. Is that a result?
Yes. It means the level was below the lowest value that laboratory's method reports. Laboratories print it that way instead of giving an exact figure.
Words you may see on this report
Tap a word for its plain-English meaning, an example line and what it does not mean.
- CRP (C-Reactive Protein)
CRP is a protein made by the liver that rises quickly when there is inflammation or infection in the body.
- ESR (Erythrocyte Sedimentation Rate)
ESR measures how fast red blood cells sink in a tube of blood over an hour; a faster rate can be a general sign of inflammation.
- ALT (Alanine Aminotransferase)
ALT is an enzyme found mainly in the liver; when liver cells are irritated or damaged, more ALT leaks into the blood.
- AST (Aspartate Aminotransferase)
AST is an enzyme found in the liver, muscles, heart and other tissues; raised levels can signal stress or damage in one of these.
- Bilirubin
Bilirubin is a yellow substance made when old red blood cells break down; the liver processes it so it can leave the body.
- Creatinine
Creatinine is a waste product from normal muscle activity that the kidneys filter out, so its blood level helps show how well the kidneys work.
- Culture and Sensitivity
A culture and sensitivity test grows germs from a sample to identify them, then checks which antibiotics can stop them.
- eGFR (Estimated Glomerular Filtration Rate)
eGFR is an estimate of how well your kidneys filter waste from your blood, calculated from a creatinine blood test plus details like age.
- Electrolytes
Electrolytes are minerals in the blood, such as sodium, potassium and chloride, that carry an electric charge and help the body work.
- Fasting Sample
A fasting sample is blood taken after you have had nothing to eat or drink except water for a set number of hours.
- Ferritin
Ferritin is a protein that stores iron; its blood level gives a good idea of how much iron the body has in reserve.
- HbA1c
HbA1c shows your average blood sugar over roughly the past two to three months by measuring how much sugar is attached to red blood cells.