For people with celiac disease hidden gluten in their diets is the main cause of elevated Tissue Transglutaminase IgA Antibodies (tTG-IgA), but there are other conditions, including cow's milk/casein intolerance, that can also cause this, and here is an article about the other possible causes:    

One thing I've learned over many years here, is that everyone needs to be their own health advocate, and that may include not trusting what some doctors may say or do. In my case I had gluten sensitivity issues all my life, but for ~5 years full blown celiac disease and went to many doctors and was not tested for it until I specifically asked for the tests. So 5 years of torture could have been avoided. On the other side of this was a great allergy doctor that I had who warned me 5 years before all that happened that I should not eat wheat more than once per week--and I ignored him. So there are both bad doctors, and bad patients!

Perhaps the sorghum was cross contaminated with a gluten containing grain in the field or in harvesting, transport, storage or processing. Or it could be that something other than gluten is causing a gluten-like reaction when you consume sorghum. But the fact is, the protein component of sorghum is different than gluten. Gluten is found only in wheat, barley, rye and some cultivars of oats.

In some countries, like the UK, there are tangible benefits to having an official celiac diagnosis such as government stipends to offset the cost of gluten free food and supplemental follow-up care. Also, some people find it difficult to stay on the gluten free bandwagon without an official diagnosis. But I hear you. If the toll on your health and livelihood is too great to stay the course with the gluten challenge until the biopsy, it isn't smart to do so. By the way do you have access to the celiac antibody blood test scores? Along with the reference ranges? We don't know where you live but in Europe it is becoming increasingly common for physicians to declare an official diagnosis of celiac disease based on the blood test alone if the TTG-IGA score is 10x normal or greater.

Hello! My daughter was diagnosed last year. Her ttg was 21.5 at the time; went to 8.6 a month later; 5.4 six months later; and is 6.1 now. 15 and over is considered abnormal, so we are “ok” right now. Im wondering how I can get her to as close to 0 as possible. I am also wondering why there is a normal range of anti-ttg, as I don’t think it’s a good thing to have? What could contribute to having this present other than celiac. We are a gluten free household, rarely eat out. We don’t eat oats or many grains in general. thank you!