The What and Why: Inflammation & CRP

Disclaimer: This information is based on my own research into this particular aspect of IBD as well as some personal experience and should not be used as medical advice or a diagnostic tool. The suggestions given within are taken from sources laid out in the references header.  If you seek advice regarding the things you experience within your own disease, please contact your IBD team for medical advice.

If you are looking for the entire ‘What and Why’ series, you can find them all here.

What is Inflammation & CRP?

Inflammation is the process in which the body’s white blood cells and substances they produce protect us from infection with foreign organisms, such as bacteria and viruses.

CRP – C-Reactive Protein is the most sensitive ‘acute phase protein’ and is the top choice in most situations when detection or monitoring of the acute phase response is required.  It has a rapid response time and will rise within two hours of acute insult – surgery or infection, for instance. CRP has a short half-life (8 hours) and should peak and begin decreasing within 48 hours if no other inflammatory event occurs.

Why is it important?

Inflammation and the body’s response to it is a normal process of the immune system. It provides us with a warning to fight off infections which might become life threatening.

However, in some instances, the body’s defense system – the immune system – triggers an inflammatory response when there are no foreign invaders to fight off. In these ‘autoimmune diseases’ the body’s normally protective immune system causes damage to its own tissues. The body responds as if normal tissues are infected or somehow abnormal.

What is the relevance to IBD?

CRP is a general, nonspecific marker of inflammation. CRP levels rise early after the onset of inflammation and decrease rapidly after its resolution. An elevated CRP result demonstrates the presence of inflammation and is consistent with active IBD.

An elevated CRP result strongly suggests active disease. In Crohn’s Disease patients, CRP concentrations correlate with more severe endoscopic disease activity. Where as in Ulcerative Colitis patients, failure of CRP normalisation should prompt consideration of further endoscopic evaluation, regardless of symptoms.

Confirmation of inflammation is often the first step in the IBD differential diagnosis. Four markers are available: C-Reactive Protein (CRP), erythrocyte sedimentation rate (ESR), fecal calprotectin and quantitative fecal lactoferrin. When inflammation is present, anti-neutrophil cytoplasmic antibody (ANCA) and anti-Saccharomyces cerevisiae antibody (ASCA) tests can be used to help differentiate Ulcerative Colitis and Crohn’s Disease. From here, they will use radiology, endoscopy, and histology to confirm the diagnosis of IBD and the differentiation of UC and CD.

How can it be resolved?

Once identified, medications are used to lower the CRP and control the condition associated from the high CRP levels.

For IBD this usually means starting cortisteriods and potentially immunosuppressants, in cases where the disease is unable to be controlled after endoscopy and histology results come back.

CRP is usually monitored for all the medications taken for IBD. They are usually also taken when your IBD team suspect you might be suffering from a flare up, as CRP will establish how high the inflammation markers are within the body.

Typically, an ideal level of 10mg/l is considered good with IBD, but for some blood work does not show a true picture of the inflammation inside the body.

Important information

  1. ESR – erythrocyte sedimentation rate, or sed rate –  is a measure of the rate of which red blood cells sediment in a period of one hour. This is sometimes used in combination with CRP to give an indication of inflammation. High ESR indicates inflammation, but can sometimes show false negatives.  Levels of ESR are naturally higher in women and increase as you age.
  2. Generally, CRP levels of 10–40 mg/l are found in cases of mild inflammation or viral infections. Severe active inflammation or bacterial infection will typically generate CRP levels of 50–200 mg/l, and very high levels of >200–250 mg/l are only found in severe conditions and burns.
  3. CRP is an objective marker of inflammation and correlates well with disease activity in Crohn’s Disease. Increased CRP levels are associated with better response rates and normal CRP levels predict high placebo response rates in clinical trials with biologicals.
  4. CRP should not be used a stand alone test for diagnosing IBD. It is a guide to assess inflammation in the body, which could be a number of things – ranging from a cold to a heart attack.
  5. Using Fecal Calprotectin along side CRP and ESR gives more solid results for assessing inflammation in the gut. Adding in radiology and endoscopy can confirm as suspicion of IBD as well as confirming the differences in CD and UC – ie, the depth and location of damage to the gut lining.

My Experience

I’ve had my CRP checked hundreds of times over the last seven years. It was at its highest shortly after diagnosis – roughly in the 320 mg/l range – and at its lowest when Humira had got me to clinical remission, my CRP was 4 mg/l.

In between those times, and since – especially after and pre surgery/ies.- my CRP has been raised and it has been the first indication of a flare up. Anything above 40 mg/l was a strong indication to begin on a new medication or to start a short course of steroids to dampen down the effects of inflammation. The level of when to intervene is dependent on NHS Trust and their own guidelines alongside those of the BSG – British Society of Gastroenterlogy.

I’ve never had trouble with a blood test when they were taking samples for inflammation. I have however, always had issues with all blood tests due to small veins and persistent dehydration. Whilst I can plan ahead for my regular and routine blood tests, those ones that happen off the cuff used to be a problem. However, I just allow the phlebotomist to take their time and let them poke me more than one. I’ve become more and more used to the multiple pokes.

Have you experienced raised CRP and inflammation markers? Has your team explained the significance to you? Do you get tested often? Why is this?

Do you have any questions or queries? Or just want to share your own experiences? Leave me a reply or tweet me @sapphire20 or find my blog page on Facebook!


Crohn’s Colitis Foundation of America: Diagnosising and Managing IBD

IBD Relief: Blood Tests for IBD

Quest Diagnosis: IBD – Laboratory Support of Diagnosis and Management

NCBI: World Journal of Gastronenlogy – Disease Monintoring in Inflammatory Bowel Disease

NCBI: BSJ Gut – Laboratory Markers in IBD: useful, magic or unnecessary toys?


  • Ailish Doohan

    05/06/2018 at 08:48

    Hi, thank you for sharing your story. I am just wondering how you plan ahead for your routine blood tests. I have started having problems getting bloods. I was always OK in the past but after numerous hospital stays, surgery for ileostomy due to UC, & lots of biologic drugs, my veins aren’t so good anymore. So any tips greatly appreciated.

    1. Admin

      05/06/2018 at 20:16

      Hiya! If I know my bloods are due I tend to drink lots of water the evening before. My IBD Nurse always said it was easier to get a stick if I was hydrated and that would be fluids 24 hrs prior to my bloods. I always show them where to get my blood from, and which type of needle to use. Smallest is usually better for me. And as weird as it sound, relax. I think our bodies tense up and it makes the veins dive down when a needle is produced to the skin. Failing that, warming your arms up by wearing long sleeves, walking abit to the appointment so you have your blood bumping. Hope that helps. I have a blood test post coming in a week or so, that might be helpful too.

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