It’s been a busy three weeks since I attended the 2013 International Celiac Disease Symposium (ICDS) in Chicago and I have dedicated only two posts to the symposium thus far (as I was reminded by my friend last night). So, here is some more information for you. This will be post #3 of about 9 or 10 total.
On the first day of the conference, Dr. Benjamin Lebwohl from Columbia gave a lecture entitled “The Correct Diagnostic Approach.” Some of his bullet points on the diagnosis of Celiac Disease included the following:
- At the current time, most algorithms for diagnosis use both blood tests (serology) and a small bowel biopsy.
- The TTG IgA antibody is the blood test that is the most sensitive and specific for Celiac Disease. If a patient has a selective IgA deficiency (occurs in about 3% of the population), the deamidated gliadin peptide IgG (DGP IgG) can be useful for screening. The DGP IgA antibody is also more sensitive than the TTG IgA antibody in children under the age of 2.
- The Celiac antibody tests are imperfect. In approximately 10% of Celiac patients, at time of diagnosis the antibody tests will be negative (normal) but there is still damage seen on biopsy. If these patients had only blood tests performed, their cases of Celiac Disease would be missed.
- All patients with Irritable Bowel Syndrome (IBS) should be tested for Celiac Disease.
- It is not feasible to screen all people for Celiac Disease because the positive predictive value (PPV) of the Celiac tests is too low. PPV refers to the percentage of patients with a positive test result who actually have a disease. He stated that if all people were screened, 2/3 of people with abnormal Celiac antibodies would actually not have Celiac Disease (too many false positives) .
- Lastly, he reminded us that it is crucial that 4 to 6 biopsies be taken during endoscopy, as the damage from Celiac Disease can be missed if too few biopsies are taken. There are many people walking around who have Celiac Disease but were told that their small bowel biopsies were normal because not enough biopsies were taken. If you are interested in reading more about this, I discussed this in a recent post.
Later in the day, Dr. Enzo Bravi from Europe discussed rapid “point of care” tests for Celiac Disease. There are several tests on the market that require only a few drops of blood and can give results in 5 to 10 minutes. Simtomax and Biocard are two examples that are used in Europe and other parts of the world. All of the rapid tests look for some combination of antibodies (TTG IgA, total IgA, DGP IgA and IgG, etc). There are hopes that these tests will be especially useful in pediatric populations and in developing countries. Dr. Bravi is currently researching if these tests can be used to assess compliance with the GF diet in Celiac patients who are already GF. He emphasized that these tests are not intended to be used for the final diagnosis of Celiac Disease. For more on the Simtomax tests, please see link. I had an opportunity to briefly speak with Dr. Bravi during one of the breaks and learned that none of these tests are FDA approved for use in the U.S. If/when they are approved, I would love to be able to use them in a clinical research study!
Session 4 of the ICDS focused on the pathology of Celiac Disease. The speakers were Drs. Marsh, Hart, and Bhagat. We were reminded that small intestinal (duodenal) tissue biopsies are graded from Marsh Type 0 (normal) to Type 3 (villous atrophy and destruction). Types 1 and 2, the intermediate lesions, have infiltration of tissues with white blood cells, which is called intraepithelial lymphocytosis (IEL). Type 2 also includes tissue hyperplasia, or thickening.
Type 1 lesions, with IEL only, can be seen in IBS and other causes of malabsorption. If a patient has a Marsh Type 1 lesion in the duodenum and positive TTG antibodies, the diagnosis is either Celiac Disease or Crohn’s Disease. If anti-endomysial antibodies are present, it is Celiac Disease, and if they are absent, it is Crohn’s Disease.
There are several other diseases that can cause villous blunting that is similar to that seen in Celiac Disease. They include the following:
- Olmesartan associated enteropathy
- Common variable immunodeficiency (CVID)
- Crohn’s Disease
- Giardia infection
- Tropical sprue
- Autoimmune enterocolitis
CVID, an immunodeficiency, has a mean age of diagnosis of 35. Two thirds of patients with CVID have increased IEL +/- villous atrophy on their biopsies. Celiac antibody tests are often negative. Patients with CVID have no improvement on the gluten free diet. This is one of the biggest red flags that CVID is a possibility for a patient. CVID needs to be ruled out in cases of refractory (non-responsive) Celiac Disease.
Olmesartan is a medication used for high blood pressure (hypertension) that is in a category of drugs called ACE inhibitors. It can cause duodenal damage that is almost identical to that seen in Celiac Disease. Colchicine is another drug that can cause similar bowel changes.
The speakers emphasized that in patients with refractory Celiac Disease (that do not respond to the gluten free diet), #1-6 need to be excluded.
More information from ICDS to come, including what to do for those with “potential” Celiac Disease and nutrional aspects of Celiac Disease. Thank you for both reading and being patient with me!