Summary: Celiac.com 02/05/2023 - If you have celiac disease symptoms, for example chronic diarrhea, anemia, bloating, abdominal pain, rashes, are in a higher risk group, etc., your doctor may order a blood test for celiac disease. Note that before doing the blood test you must be eating gluten for a while beforehand, and the amount and length of time can vary, but is somewhere between 2 slices of wheat bread daily for 6-8 weeks and 1/2 slice of wheat bread or 1 wheat cracker for 12 weeks, to be accurately tested celiac disease, otherwise you may end up with false negative results. For a celiac disease antibody test, a clinician collects a small amount of the patient's blood. The sample is then sent to a lab, where the blood cells are then removed, and the test is conducted. The Celiac Disease Blood Screening Panel A full blood panel for celiac disease includes all of the following tests: tTG-IgA and tTG-IgG tests (specific for celiac disease) EMA-IgA test (specific for celiac disease) DGP-IgA and DGP-IgG tests (specific for celiac disease, not always included in adults, but should always be included when screening children, especially if they are under 2 years old) IgA deficiency (to determine the accuracy of the first two tests above) Celiac Disease Blood Antibody Screening in Children - Deamidated Gliadin Peptide IgA/IgG Antibody Levels (Also known as DGP tests) DGP screening should always be done in children, especially in those who are 2 years old or younger. The DGP test is not as sensitive or specific as the tTG-IgA test, but it may be used by healthcare professionals in certain situations. For example, in children under 2 years old, the DGP test may be combined with the tTG-IgA test due to their lower sensitivity. For those with IgA deficiency, the DGP-IgG test may be used. The DGP test was created to detect celiac disease in those with IgA deficiency, as it tests for both IgA and IgG antibodies. To obtain accurate results, those screened need to be eating gluten daily, at least 1/2 slice of wheat bread or 1 wheat cracker for at least 12 weeks leading up to the tests, just like the tTG test (be sure to check with your doctor for the latest protocol). The IgG tTG test is slightly less accurate than the IgG DGP test, while the IgA tTG test is more accurate and specific than the IgA DGP test. Celiac Disease Blood Antibody Screening is ~98% Accurate in Adults Using This Protocol A celiac disease blood panel includes several tests to determine whether someone has celiac disease. These tests are very specific because certain antibodies only appear in those with gluten sensitivity, celiac disease and/or dermatitis herpetiformis. Testing begins with a test called Immunoglobulin A (IgA). If the results are normal, then a Tissue transglutaminase, antibody, IgA test is given. A weak positive should lead to the following tests: Endomysial antibodies (IgA) and; Gliadin (deamidated) antibody, IgA. If the initial Immunoglobulin A (IgA) test is lower than normal, then these two tests should be done: Tissue transglutaminase antibodies, IgA and IgG profle. Gliadin (deamidated) antibodies evaluation, IgG and IgA. If the initial Immunoglobulin A (IgA) test is below the level of detection (<1.0 mg/dL), then these two tests should be done: Tissue transglutaminase (tTG) antibody, IgG. Gliadin (deamidated) antibody, IgG. It sounds complicated, but it's pretty standard procedure now, and when blood screening is done this way the results for celiac disease are ~98% accurate. Many People Can Be Diagnosed Using Only Blood Tests and No Biopsy According to the latest research, if the blood test results are at certain high levels that range between 5-10 times the reference range for a positive celiac disease diagnosis, it may not be necessary to confirm the results using an endoscopy/biopsy: Blood Test Alone Can Diagnose Celiac Disease in Most Children and Adults TGA-IgA at or Above Five Times Normal Limit in Kids Indicates Celiac Disease in Nearly All Cases No More Biopsies to Diagnose Celiac Disease in Children! Biopsy Still Standard in Adult Celiac Diagnosis After positive blood tests some doctors still require a biopsy to confirm the diagnosis. However, this is changing, as new techniques allow doctors to accurately detect celiac disease in adults without a biopsy. Remember, nearly all tests and screening for celiac disease require the patient to be eating a gluten-containing diet before testing, usually you should be eating at least 1/2 slice of wheat bread or 1 wheat cracker daily for at least 2 weeks before the endoscopy. Be sure to check with your doctor for the latest protocol. Blood Tests for Follow Up Care Blood tests may also be useful in follow up care in those with celiac disease to confirm that their diet is indeed free of gluten. Also, because of the lack of standardization, keep in mind that blood test results may not be directly comparable from one lab to the next. More Celiac Disease Testing Resources What is a Gluten Challenge and How Long Must it Last? Interpretation of Celiac Disease Blood Test Results Ten Facts About Celiac Disease Genetic Testing Blood Test Questions on the Celiac Disease and Gluten-Free Forum Test results and question about gluten challenge How Long To Eat Gluten For Accurate Blood Test Read more at mayocliniclabs.com
