It’s tempting to assume that doctors are up on all the latest research. But celiac and gluten-intolerance research is changing fast, and much of what doctors were taught about it is no longer the best information out there. In the past 15 years the estimates of how many people have celiac disease have gone from 1 in 10,000 to at least 1 in 133! So forgive your doctors if they do not think to check for it without some prompting!
Since realizing that doctors can’t possibly know everything and ask all the right questions during every visit, I’ve changed my approach to doctor visits, with great results. If you are considering getting tested for celiac, make sure to ask your doctor about all of these tests:
Labs for Celiac Screening
In order to get valid results, you must be eating a full gluten diet (at least 20 grams a day) for at least 3 months prior to testing. Some anti-inflammatory medications such as steroids (even topical) used in the month prior to testing can also invalidate results.
When your labs come back, get a full copy of them, along with the reference ranges. Reference ranges tell what the normal range of values is for each test. Without this information, you won’t be able to interpret your results, since every lab is a bit different. With a copy of your test results, you will be able to get a second opinion on your doctor’s interpretation of them.
Celiac disease is defined by damage already done to the lining of the small intestine. The “gold standard” diagnosis is biopsy of the small intestine. Because of this, many doctors will not give a diagnosis of celiac disease on blood work alone. However, blood work is usually the first step in screening for celiac disease because biopsies are so invasive. Researchers are now finding that there are many forms of gluten intolerance. They are also finding that people with positive bloodwork who have negative biopsies can go on to develop classic celiac damage. Positive bloodwork is a very strong sign that you have celiac disease.
Here is the list of tests included in a typical full celiac panel:
- Total IgA (Immunoglobulin Antibody) Some people have low total IgA. If you are deficient in Total IgA, the other tests involving IgA are invalidated.
- tTG IgA (Anti-tissue Transglutaminase) This is very strongly correlated with celiac disease, however, some people with diseases such as Type 1 Diabetes, Hashimoto’s thyroiditis, HIV, and autoimmune liver conditions can have a falsely positive tTG test. Those conditions all have a higher incidence in celiacs, though, so there is a chance you may have both conditions.
- EMA IgA (Anti-endomysial Antibody) This test is very specific to celiac disease. If these levels are elevated it’s celiac! However, this test is not as sensitive as tTg IgA
- AGA IgA (Antigliadin IgA antibodies) Positive results indicate intolerance, and potential for celiac. Is being repaced by DGP IgA
- AGA IgG (Antigliadin IgG antibodies) Positive results indicate intolerance, and potential for celiac. This may be positive in people with low Total IgA.
- DGP (anti-Deamidated Gliadin Peptide) IgA This is a newer test. It is more specific to celiac disease than the tTG and AGA tests, and can sometimes catch celiac disease in younger children and people with deficient Total IgA.
- DGP (anti-Deamidated Gliadin Peptide) IgG This is a newer test, replacing AGA IgG
Update:Cyrex Labs has more comprehensive panels available, that include these tests but test for more ways you could be reacting to gluten, and other foods that could be triggering similar responses. Many of the naturopaths I know are now using them. Check out the list of available tests here.
- find out the extent of the damage establish a baseline for follow-up testing
- confirm a negative diagnosis
- receive an official diagnosis
If receiving an endoscopy, make sure that the doctor plans to take 6-8 samples from different areas of the small intestine and duodenum and that they will be sent to a qualified lab even if they “look fine.” The samples will be viewed under a microscope and given a Marsh score that tells how severe the damage is. A colonoscopy is not the same as an endoscopy and can not diagnose celiac disease. There are a few other conditions that can cause a positive result. However, false negatives are far more common. Celiac damage isn’t uniform, and in the early stages it can be hard to spot.
People who have a negative biopsy but positive blood work or a family history of celiac are sometimes told to stay on a gluten diet and retest every three years. Other doctors treat positive blood work as a positive diagnosis, and recommend a completely gluten-free diet.
Update 1/26/2012: There are new standards for official diagnosis of celiac disease in children without biopsy coming out.
Celiac bloodwork and endoscopy may be negative, but a dermatitis herpetiformis diagnosis still makes you positive for celiac disease. People with dermatitis herpetiformis usually need to drastically reduce their iodine intake in addition to completely cutting out gluten.
DNA testing can give you an idea of how likely it is that you have celiac disease. But since this post was so long, it got its own post!
So… Doctor Knows Best? Myth: Plausible
Check out the other myths we’ve exposed so far:
- Celiac Testing Myth #1 – No Symptoms = No Celiac
- Celiac Testing Myth #2 – Go Gluten-Free First
- Celiac Testing Myth #3 – Gluten-Free 4 Life = No Reason to Test
- Celiac Testing Myth #5 – DNA = Proof
- Celiac Testing Myth #6 – Negative Results = No Problems
- Wheat Allergy and Non-celiac Gluten Intolerance
This post is a part of Food Renegade’s Fight Back Friday!