C-Reactive Protein (CRP) Test – Everything You Need to Know

What is C-Reactive Protein?

C-Reactive Protein (CRP) is a protein made by the liver in response to injury or infection1. Because of this, it is the first indicator of any infections, injuries or inflammation within the body1. CRP increases before other symptoms such as pain or increased temperatures show up1. CRP levels can increase into the thousands as a response to inflammation caused by a disease or other routes of harm for the body1.

Although it is a sensitive measurement for inflammation, it does not indicate the location of the inflammation or infection in the body1. However, there is a higher sensitivity version of the CRP test which can be used to identify very small scale changes that can be used in regards to heart health called the CRP hs test1.

What is inflammation?

Essentially, inflammation occurs when the body floods helpful cells into an area of damage, often causing swelling2. This is why when you get a cut, the area around the cut appears redder and can be hotter than surrounding skin, due to the increased amount of blood and cells2. There are two types of inflammation:

Acute Inflammation

Acute is a medical term that directly means sudden onset2. When used in regards to inflammation, this indicates that the inflammation is localised to a specific area and will reduce within days3.

Chronic Inflammation

Chronic inflammation refers to an inflammation response that lasts more than a month and can even last years3. This can occur both in a localised area of an injury or can be systematically throughout a larger area covering several organs. For example, in long-term digestive disorders such as inflammatory bowel disorder, inflammation can affect any of the digestive organs of the small intestines, large intestines, stomach, and mouth.

Why is it necessary to track CRP levels?

As mentioned before, CRP can increase before you experience any symptoms of the source of harm in your body. Having advanced warning signs of upcoming issues can help you change your daily routines to boost your immune system. Thus speeding up the recovery process!

Alongside this, some long term conditions cause CRP levels to increase and a hs CRP test is, therefore, a great way to monitor the status of that condition.

When should you get a CRP test?

In a medical view, whenever you do not feel 100%, a CRP test is carried out to identify if there is an infection. Although ElevateMe is not a medical diagnostic service, regular CRP tests can help create a picture of your overall health and the ability of your immune system to react to any infections and diseases.

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What is the difference between a CRP test and an hs-CRP test?

The hs-CRP test is fairly new and is yet to be used in widescale practice. Furthermore, the hs-CRP test is an extremely sensitive test that identifies small units of CRP to give a more accurate reading. This becomes useful when assessing heart health due to atherosclerosis (build-up of fat within blood vessels) being connected to long-term low-level inflammation4. More information on atherosclerosis and heart health is available in our post on the cholesterol test here.

hs-CRP test for heart disease

The hs-CRP test is useful for monitoring prolonged yet low levels of inflammation that point to atherosclerosis. However, the test reads inflammation levels within the entire body4. To be effectively used for heart assessment, other blood tests are also needed such as a cholesterol test and other fat level blood tests4.

There have been some studies that are investigating the use of hs-CRP tests alone and in conjunction with other tests. However, as this is such a new area, there has not been enough evidence to establish the limitations of the blood test alone4.

CRP test for autoimmune diseases

Autoimmune diseases are conditions where your own immune response inadvertently attacks healthy parts of the body. There are several different types and a number of conditions that fall into this bracket. Because this is a condition that means the immune system is active whilst experiencing the symptoms of the disease, this results in a raised CRP level.

The increasing CRP levels then create a great way to monitor the severity of the disease. Often with autoimmune diseases, the condition may not be constantly active and can be triggered to become active, however, the trigger is not always known. Thus, people who suffer from these conditions can use CRP monitoring as an early warning sign for their condition to become active.

What are the normal values for CRP blood test?

We have opted to use the more sensitive version of the CRP test, the hs-CRP test, as part of our home blood testing. This means that we will be able to identify even trace amounts of CRP in your blood.

According to most labs, the reference normal value of hs-CRP for individuals who have no underlying health issues should be below 10mg/L 1.

However, at ElevateMe, we use optimal ranges which are different from reference ranges. Optimal ranges are developed using the average values of the healthiest of individuals. Here are the optimal ranges for hs-CRP. For an optimum life, you should have values in the green (optimal) band.

Optimal Range for hs-CRP test (in mg/L)
Optimal Range for hs-CRP (in mg/L)

What does a high CRP test value mean?

When CRP levels increase, there is an indication of inflammation and an underlying illness or condition causing this1. CRP can also increase after intensive and moderate exercise5. However, this is temporary and will reduce to normal levels over several hours.

How can you lower your CRP test result?

The most effective way to reduce your CRP levels is through exercise, weight loss and dietary control6. Although all diets to lose weight will reduce CRP levels, examples of proven ones include the Mediterranean diet,7 Atkins diet, zone diet, Ornish diet and weight watchers6.

Specifically, there are groups of foods that lower your CRP levels:

  • Berries- including strawberries, blueberries, raspberries & blackberries8.
  • Fatty Fish – salmon, sardines, herring, mackerel and anchovies9.
  • Broccoli10,
  • Avocados11,
  • Green Tea12,
  • Peppers13,
  • Mushrooms14,
  • Grapes15,
  • Cherries16.

Are there people with higher risk for high CRP?

There is an increased risk for people who:

  • are within the third trimester of pregnancy,
  • use oral contraceptives,
  • undergo hormone replacement therapy,
  • are overweight.1

In conclusion

CRP directly points to any inflammation or damage your body is currently trying to recover from. Keeping this in review will enable you to identify any upcoming issues and change your daily routine to boost your immune system to help tackle these issues.

Frequently Asked Questions

Q. Can CRP test detect cancer?

A. No. Although some cancers can produce inflammation, CRP only detects general inflammation within the body.

Q. Can CRP test detect lymphoma?

A. No. Although some cancers can produce inflammation, CRP only detects general inflammation within the body.

Q. Can CRP test detect covid?

A. No. COVID, like any illness, triggers the immune system to act. This then increases CRP levels, but cannot be used to specifically identify an illness.

Q. Can CRP test detect HIV?

A. No. HIV, like any illness, triggers the immune system to act. This then increases CRP levels, but cannot be used to specifically identify an illness.

Q. Can CRP test detect TB?

A. No. TB, like any illness, triggers the immune system to act. This then increases CRP levels, but cannot be used to specifically identify an illness.

Q. Can CRP test detect pregnancy?

A. No. Pregnancy causes many changes from your normal levels for several biomarkers. Pregnancy should always be confirmed using a dipstick pregnancy test or blood test.

Q. What kinds of foods increase CRP levels?

A. Fast foods17, fried food and sugar-sweetened drinks18, can all increase CRP levels.

Not feeling great? 

Any kind of inflammation in the body will make you feel unwell. A CRP test checks if your body is actively fighting some illness, infection, disease, or injury.  

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1 Lab Tests Online. (2018). C-Reactive Protein. Last accessed 12/08/2021.

2 Waugh, A (2018). Anatomy and Physiology in Health and Illness. 13th ed. London: Elsevier.

3 Openlearn. (2012). Histopathology. Last accessed 12/08/2021.

4 Lab Tests Online. (2018). hs-CRP. Last accessed 12/08/2021.

5 Cerqueira, E., Marinho, D., Neiva, H. & Lourenco, O. (2020). Inflammatory Effects of High and Moderate Intensity Exercise—A Systematic ReviewFrontiers in Physiology. 10 (1550), ID: 10.3389/fphys.2019.01550.

6 Ridker, P. (2005). C-Reactive Protein, Inflammation, and Cardiovascular DiseaseTexas Heart Institution Journal. 32 (3), 384-386.

7 Casas, R. et al. (2014). The effects of the Mediterranean diet on biomarkers of vascular wall inflammation and plaque vulnerability in subjects with high risk for cardiovascular disease. A randomized trial. PLoS One. 9 (6), e100084.

8 Joseph, S., Edirisinghe, I. & Burton-Freeman, B. (2014). Berries: anti-inflammatory effects in humans. Journal of Agricultural and Food Chemistry. 62 (18), 3886-3906.

9 Weylandt, H., Chiu, C-Y., Gomolka, B., Waechter, S. & Wiedenmann, B. (2012). Omega-3 fatty acids and their lipid mediators: towards an understanding of resolvin and protectin formation. Prostaglandins Other Lipid Mediators. 97 (3-4), 73-82.

10 Hwang, J-H. & Lim, S-B. (2014). Antioxidant and Anti-inflammatory Activities of Broccoli Florets in LPS-stimulated RAW 264.7 Cells. Preventive Nutrition and Food Chemistry. 19 (2), 89-97.

11 Li, Z. et al. (2013). Hass avocado modulates postprandial vascular reactivity and postprandial inflammatory responses to a hamburger meal in healthy volunteers. Food and Function. 4 (3), 384-391.

12 Molina, N., Bolin, A. & Otton, R. (2015). Green tea polyphenols change the profile of inflammatory cytokine release from lymphocytes of obese and lean rats and protect against oxidative damageInternational Immunopharmacology. 28 (2), 895-896.

13 Kang, J-H., Kim, C-S., Han, I-S., Kawada, T. & Yu, R. (2007). Capsaicin, a spicy component of hot peppers, modulates adipokine gene expression and protein release from obese-mouse adipose tissues and isolated adipocytes and suppresses the inflammatory responsesFEBS Letters. 581 (23), 4389-4396.

14 Elsayed, E., Enshasy, H., Wadaan, M. & Aziz, R. (2014). Mushrooms: a potential natural source of anti-inflammatory compounds for medical applicationsMediators of Inflammation, ID 805841.

15 Tomé-Carneiro , J. et al. (2013). Grape resveratrol increases serum adiponectin and downregulates inflammatory genes in peripheral blood mononuclear cells: a triple-blind, placebo-controlled, one-year clinical trial in patients with stable coronary artery diseaseCardiovascular Drug Therapy. 27 (1), 37-48.

16 Kelley https://pubmed.ncbi.nlm.nih.goKelley, D., Adkins, Y., Reddy, A., Woodhouse, L., Mackey, B. & Erickson, K. (2013). Sweet bing cherries lower circulating concentrations of markers for chronic inflammatory diseases in healthy humansJournal of Nutrition. 143 (3), 340-344.

17 Lopes, A., Araújo, L., Levy, R., Barreto, S. & Giatti, L. (2019). Association between consumption of ultra-processed foods and serum C-reactive protein levels: cross-sectional results from the ELSA-Brasil study. Sao Paula Medical Journal. 137 (2), 169-176.

18 Buyken, A., Goletzke, J., Joslowski, G., Felbick, A., Cheng, G., Herder, C. & Brand-Miller, J. (2014). Association between carbohydrate quality and inflammatory markers: a systematic review of observational and interventional studiesAmerican Journal of Clinical Nutrition. 99 (4), 813-833.

CRP test to detect illness - ElevateMe

Written by Louise Taylor

After completing Clinical Technology at the University of Bradford, I am venturing into the NHS as a General Medical Engineer.


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