The first set of results show two positive results for celiac disease, so at the very least it looks like you could have it, or at the least NCGS.   Approximately 10x more people have non-celiac gluten sensitivity than have celiac disease, but there isn’t yet a test for NCGS. If your symptoms go away on a gluten-free diet it would likely signal NCGS.      

Elevated tissue transglutaminase IgA (tTG-IgA) levels are highly specific for celiac disease, and they are a key biomarker used in its diagnosis. However, there are some rare instances where elevated tTG-IgA levels have been reported in conditions other than celiac disease. While these cases are not common, they have been documented in the literature. Below are some examples and references to studies or reviews that discuss these scenarios:  1. Non-Celiac Gluten Sensitivity (NCGS)    - NCGS typically does not cause elevated tTG-IgA levels, as it is not an autoimmune condition. However, some individuals with NCGS may have mild elevations in tTG-IgA due to intestinal inflammation or other factors, though this is not well-documented in large studies.    - Reference: Catassi, C., et al. (2013). *Non-Celiac Gluten Sensitivity: The New Frontier of Gluten-Related Disorders*. Nutrients, 5(10), 3839–3853. [DOI:10.3390/nu5103839](https://doi.org/10.3390/nu5103839)  2. Autoimmune Diseases    - Elevated tTG-IgA levels have been reported in other autoimmune conditions, such as type 1 diabetes, autoimmune hepatitis, and systemic lupus erythematosus (SLE). This is thought to be due to cross-reactivity or polyautoimmunity.    - Reference: Sblattero, D., et al. (2000). *The Role of Anti-Tissue Transglutaminase in the Diagnosis and Management of Celiac Disease*. Autoimmunity Reviews, 1(3), 129–135. [DOI:10.1016/S1568-9972(01)00022-3](https://doi.org/10.1016/S1568-9972(01)00022-3)  3. Chronic Liver Disease    - Conditions like chronic hepatitis or cirrhosis can sometimes lead to elevated tTG-IgA levels, possibly due to increased intestinal permeability or immune dysregulation.    - Reference: Vecchi, M., et al. (2003). *High Prevalence of Celiac Disease in Patients with Chronic Liver Disease: A Role for Gluten-Free Diet?* Gastroenterology, 125(5), 1522–1523. [DOI:10.1016/j.gastro.2003.08.031](https://doi.org/10.1016/j.gastro.2003.08.031)  4. Inflammatory Bowel Disease (IBD)    - Some patients with Crohn’s disease or ulcerative colitis may have elevated tTG-IgA levels due to intestinal inflammation and damage, though this is not common.    - Reference: Walker-Smith, J. A., et al. (1990). *Celiac Disease and Inflammatory Bowel Disease*. Journal of Pediatric Gastroenterology and Nutrition, 10(3), 389–391. [DOI:10.1097/00005176-199004000-00020](https://doi.org/10.1097/00005176-199004000-00020)  5. Infections and Parasites    - While infections (e.g., giardiasis) are more commonly associated with false-positive tTG-IgA results, chronic infections or parasitic infestations can sometimes lead to elevated levels due to mucosal damage.    - Reference: Rostami, K., et al. (1999). *The Role of Infections in Celiac Disease*. European Journal of Gastroenterology & Hepatology, 11(11), 1255–1258. [DOI:10.1097/00042737-199911000-00010](https://doi.org/10.1097/00042737-199911000-00010)  6. Cardiac Conditions    - Rarely, heart failure or severe cardiovascular disease has been associated with elevated tTG-IgA levels, possibly due to gut ischemia and increased intestinal permeability.    - Reference: Ludvigsson, J. F., et al. (2007). *Celiac Disease and Risk of Cardiovascular Disease: A Population-Based Cohort Study*. American Heart Journal, 153(6), 972–976. [DOI:10.1016/j.ahj.2007.03.019](https://doi.org/10.1016/j.ahj.2007.03.019)  Key Points: - Elevated tTG-IgA levels are highly specific for celiac disease, and in most cases, a positive result strongly suggests celiac disease. - Other conditions causing elevated tTG-IgA are rare and often accompanied by additional clinical findings. - If celiac disease is suspected, further testing (e.g., endoscopy with biopsy) is typically required for confirmation. If you’re looking for more specific studies, I recommend searching PubMed or other medical databases using terms like "elevated tTG-IgA non-celiac" or "tTG-IgA in non-celiac conditions." Let me know if you’d like help with that!

I called zero water and they state their filters do not contain gluten or gluten containing ingredients. 

I agree. Doesn't look like you have celiac disease. Your elevated DGP-IGG must be due to something else. And it was within normal at that after your gluten challenge so it is erratic and doesn't seem to be tied to gluten consumption.

Hello! I want to share my situation. I had symptoms like some food intolerance, diarrhea, bloating, belching one year ago. I thought I could have celiac disease so I did the blood tests. The results were ambiguous for me so I saw the doctor and he said I needed to do tests to check whether I had any parasites as well. It turned out I had giardiasis. After treating it my symptoms didn't disappear immediately. And I decided to start a gluten free diet despite my doctor said I didn't have it. After some time symptoms disappeared but that time it wasn't unclear whether I'd had them because of eliminating gluten or that parasite. The symptoms for both are very similar. Giardiasis also damages the small intestine. The only way to check this was to start eating bread again as I thought. Now about my results.   These are my first test results (almost a year ago) when I had symptoms: The Tissue Transglutaminase IgA antibody - 0.5 U/ml (for the lab I did the tests 0.0 - 3.0 is normal) The Tissue Transglutaminase IgG antibody - 6.6 U/ml (for the lab I did the tests 0.0 - 3.0 is normal) Immunoglobulin A - 1.91 g/l (for the lab I did the tests 0.7 to 4 g/l is normal) IgA Endomysial antibody (EMA) - < 1:10 titer (for the lab I did the tests < 1:10 titer is normal) IgG Endomysial antibody (EMA) - < 1:10 titer (for the lab I did the tests < 1:10 titer is normal) Deamidated gliadin peptide IgA - 0.3 U/ml (for the lab I did the tests 0.0 - 6.0 is normal) Deamidated gliadin peptide IgG - 46.1 U/ml (for the lab I did the tests 0.0 - 6.0 is normal)   Then I didn't eat gluten for six months. Symptoms disappeared. And I started a gluten challenge. Before the challenge I did some tests. My results: The Tissue Transglutaminase IgG antibody - 0.5 U/ml (for the lab I did the tests < 20 U/ml is normal)) Deamidated gliadin peptide IgG - 28 U/ml (for the lab I did the tests < 20 U/ml is normal)   During the challenge I ate 6 slices of wheat bread. After the challenge my results are: The Tissue Transglutaminase IgA antibody - 2.0 U/ml (for the lab I did the tests < 20 U/ml is normal) The Tissue Transglutaminase IgG antibody - 2.0 U/ml (for the lab I did the tests < 20 U/ml is normal) Immunoglobulin A - 1.31 g/l (for the lab I did the tests 0.7 to 4 g/l is normal) Deamidated gliadin peptide IgA - 2.0 U/ml (for the lab I did the tests < 20 U/ml is normal) Deamidated gliadin peptide IgG - 2.13 U/ml (for the lab I did the tests < 20 U/ml is normal)   To be sure I continued consuming gluten. I ate a lot each day. Two months after I did the tests again. My results I got today are: The Tissue Transglutaminase IgA antibody - 0.7 U/ml (for the lab I did the tests < 20 U/ml is normal) Immunoglobulin A - 1.62 g/l (for the lab I did the tests 0.7 to 4 g/l is normal) Deamidated gliadin peptide IgG - 25.6 U/ml (for the lab I did the tests < 20 U/ml is normal)   Nowadays I didn't have any symptoms except tiredness but I think it's just work. I think it was this parasite because two years ago, for example, and before I didn't have these symptoms and I always ate gluten food. But I'm still not sure especially because the Deamidated gliadin peptide IgG results are sometimes high. What do you think? @Scott Adams