What is C-reactive protein (CRP)?

An hs-CRP blood test is often included in a routine blood test, but what does CRP indicate and what can it tell you about your overall health?

What is CRP? 

C-reactive protein (CRP) is a protein produced by the liver. CRP levels rise in response to inflammation (which can be said in most situations associated with tissue damage).  

A CRP blood test will often be used to: 

  • Screen for inflammatory diseases  
  • Monitor conditions such as rheumatoid arthritis or cancer 
  • Help distinguish between viral and bacterial infections  

Acute vs low-grade chronic inflammation 

Acute and chronic are common medical terms.  

Acute refers to something that has come on quickly. Whereas chronic relates to a slow onset or a condition that lasts for an extended period.  

In the case of inflammation, acute inflammation often occurs due to infection. However, there could be other causes too.  

Causes of acute inflammation include: 

  • Rheumatological conditions  
  • Trauma  
  • Malignancies  
  • Drug reactions 
  • Organ damage  

On the other hand, low-grade chronic inflammation is usually seen in other long-term conditions.  

Causes of low-grade chronic inflammation can include: 

What is a CRP or hs-CRP blood test? 

An hs-CRP Blood Test stands for a high-sensitivity CRP test. It refers to a blood test that can detect lower levels of inflammation than traditional CRP blood tests.  

Why do I need an hs-CRP blood test? 

An hs-CRP blood test detects chronic low-level inflammation in the body, which is associated with an increased risk of cardiovascular disease. 

Therefore, hs-CRP, alongside other markers such as cholesterol, can be useful to determine your risk of heart disease.  

Any inflammatory process in the body can increase hs-CRP, such as a short-term infection or chronic inflammatory conditions like rheumatoid arthritis. So, if your levels are persistently raised, other causes should be considered.  

What is a normal CRP?  

CRP is usually present in your blood at a concentration of less than 5 mg/L. 

When used as a marker for cardiovascular risk, a higher level indicates a higher risk. The table below indicates levels and their associated cardiovascular risk. 

CRP levels table

What can a raised hs-CRP tell me about my risk of heart disease? 

Levels between 1 mg/L and 3 mg/L are considered moderate risk, and levels greater than 3 mg/L are considered high risk.  

There is data to suggest that your hs-CRP level is a stronger predictor of cardiovascular disease than unhealthy LDL cholesterol levels alone. In addition, studies propose that hs-CRP levels can be useful in identifying seemingly healthy men who are at increased risk of sudden cardiac death in the future.  

It is important to bear in mind that recent injury or illness can falsely elevate CRP levels, particularly when using this test for cardiac risk stratification. Therefore, it is advisable to wait for any acute illness to settle before taking an hs-CRP test

Can I test my CRP levels at home? 

Yes, with our CRP (High Sensitivity) Blood Test you can easily check for long-term low-level inflammation, from the comfort of your home.   

How can I lower my CRP levels naturally? 

Levels of CRP rise and fall depending on the cause of inflammation. If the cause of inflammation is something like an infection (such as a viral respiratory infection), your CRP level will fall of its own accord as your body clears the virus.  

If your CRP levels are found to be raised, often it’s recommended to have a repeat test to see whether your raised results were due to a temporary infection rather than chronic inflammation.  

On the other hand, if the cause of raised CRP level is thought to reflect low-grade chronic inflammation, and you have been found to have cardiovascular risk factors, there are certain lifestyle changes you could make to lower your CRP level.  

Lifestyle factors to reduce your CRP level and cardiovascular risk include: 

  • Stopping smoking  
  • Increasing activity levels  
  • Having a healthy weight 
  • Increasing your intake of inflammation-reducing foods 

What should I do if my CRP levels are abnormal? 

If your hs-CRP level is above 3 mg/L but less than 5 mg/L, the cause of your raised level is most likely factors such as obesity, smoking, diabetes, or leading a sedentary lifestyle. Therefore, you may be advised to make lifestyle changes to lower your levels.  

However, infections, organ damage, and autoimmune conditions can also increase your hs-CRP level, so in some cases, you may need to further assessment with your doctor.  

If you have ongoing concerns about your abnormal results, please speak to your doctor.  


  1. Nehring SM, Goyal A, Patel BC. C Reactive Protein. [Updated 2022 Jul 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan. 
  2. Landry A, Docherty P, Ouellette S, Cartier LJ. Causes and outcomes of markedly elevated C-reactive protein levels. Can Fam Physician. 2017 Jun;63(6):e316-e323. PMID: 28615410; PMCID: PMC5471098. 
  3. Mahmood SS, Levy D, Vasan RS, Wang TJ. The Framingham Heart Study and the epidemiology of cardiovascular disease: a historical perspective. Lancet. 2014 Mar 15;383(9921):999-1008. doi: 10.1016/S0140-6736(13)61752-3. Epub 2013 Sep 29. PMID: 24084292; PMCID: PMC4159698. 
  4. Ridker PM, Rifai N, Rose L, Buring JE, Cook NR. Comparison of C-reactive protein and low-density lipoprotein cholesterol levels in the prediction of first cardiovascular events. N Engl J Med. 2002 Nov 14;347(20):1557-65. doi: 10.1056/NEJMoa021993. PMID: 12432042. 
  5. Parrinello CM, Lutsey PL, Ballantyne CM, Folsom AR, Pankow JS, Selvin E. Six-year change in high-sensitivity C-reactive protein and risk of diabetes, cardiovascular disease, and mortality. Am Heart J. 2015 Aug;170(2):380-9. doi: 10.1016/j.ahj.2015.04.017. Epub 2015 Apr 18. PMID: 26299237; PMCID: PMC4548857. 
  6. GP Notebook. C-reactive protein. https://gpnotebook.com/en-gb/simplepage.cfm?ID=946536472 (accessed 4 June 2023). 



Related tests

CRP (High Sensitivity) Blood Test

Check for chronic (long-term) low-level inflammation in your body, which is a risk factor for heart disease, with our easy home finger-prick blood test

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