There is none.
There are potentially 7 tests in the initial celiac blood test. The TTG IgA and TTG IgG are the most common initial tests run for celiac disease. These test the amount of anti- transglutaminase in the blood demonstrate whether the the immune system is reacting to gluten or not. Know that the TTG IgG test predicts a positive celiac biopsy only 3% of the time, even when exceptionally high – so it has low predictability for celiac.
Yhe control test is the Total IgA test. The Total IgA test is the test that confirms the immune system is functioning properly. If the Total IgA is low, then the TTG tests are invalid. The immune system isn’t functioning enough to even produce antibodies to gluten in order to be tested.
Sometimes if the TTG IGA and TTG IGG or Total IgA test are negative, there are additional tests that can be run. The DGP IgA and DGP IgG is one additional test that looks for deanimated gluten peptide. It is less accurate than the TTG testing. There is also the EMA IgA and EMA IgG tests as well. The EMA tests are the most difficult to run in the lab and have the most room for error but is the most specific to celiac. EMA stands for anti-endomysial antibody.
If any of the above tests are positive, please get an upper endoscopy with biopsy through a board certified gastroenterologist.
Now, many, many people test negative on the blood tests. Many times doctors then refuse an endoscopy because the celiac blood tests are negative. Lots of people are then still searching for answers, believe they have an issue with gluten, and will look for alternative testing to confirm their issue with gluten.
Let’s talk a little about the immune system first. There are lots of different types of cells in the immune system. The five classes of antibodies are:
- Immunoglobulin A (IgA), which is found in high concentrations in the mucous membranes, particularly those lining the respiratory passages and gastrointestinal tract. This is why the IGA testing is most accurate for celiac diease, because these cells are in the gastrointestinal tract.
- Immunoglobulin G (IgG), the most abundant type of antibody, is found in all body fluids and protects against bacterial and viral infections.
- Immunoglobulin M (IgM), which is found mainly in the blood and lymph fluid, is the first antibody to be made by the body to fight a new infection.
- Immunoglobulin E (IgE), which is associated mainly with allergic reactions (when the immune system overreacts to environmental antigens such as pollen or pet dander). It is found in the lungs, skin, and mucous membranes. This is the stuff of patch tests and anaphylactic reactions.
- Immunoglobulin D (IgD), which exists in small amounts in the blood, is the least understood antibody.
So, now that we know all about the immune system functions.
IGG allergy testing is often the first stop. This is a blood test – like those from chiropractors, functional medicine doctors, Everlywell, or other testing sources. These tests do not indicate an actual intolerance to food, but that these foods are consumed often. Eliminating the foods that indicate a sensitivity on these tests might be foods that are perfectly healthy and eliminating them may cause burden and an unnecessarily restrictive diet.
There are also stool tests that look at gluten antibodies in the stool. There is no scientific or anecdotal evidence these tests are accurate.
Fecal fat tests may indicate a malabsorption issue in the digestive tract. Malabsorption may be celiac or it may be something else and needs further investigation.
Hair tests are not accurate and are full of hype. Just don’t do it.
Genetic testing is good to get. It lets you know if you carry the genetic markers for celiac disease, but does not indicate whether you have the disease or not. For example, based on my genetic markers I have a 3% chance of developing the disease. I have it. 🙁 My mother has a 40% chance of developing the disease and she does not have it. Has never had gastrointestinal issues.
That’s all I can think of now. Let me know if there are other tests that you can think of, but just be careful. There are lots and lots of charlatans out there. There are people that will take your money, run tests, and tell you that you have issues with gluten because you have the test to prove it. Know that you may or may not have issues with gluten but it doesn’t take money to figure it out.