I don't know about the accuracy of blood tests vs. stool/saliva tests. However, when I stopped eating gluten my blood pressure dropped from systolic often at 200 to normal. This was a complete surprise and a long story. I had a terrible problem with canker sores. I heard that you can have celiac disease with NO gi symptoms and at that time I didn't have typical gi symptons, just pain. No doctor was going to test me for celiac disease without symptoms, so I thought. So, I cut out gluten myself. This is not advised because to be formally tested I had to go back to eating gluten. I wasn't expecting it at all, but a few weeks into the diet my blood pressure returned to normal and I had to go off my blood pressure meds (I was on two, searching for a third) . I have read about this in some medical literature. While on this gluten free diet I developed inflammatory arthritis of the knee which was probably the CD.
I decided to be formally tested so went to a gi doctor who was in charge of the local celiac support group. He agreed that you can have celiac with a negative blood test (even the more specific ttGA) and no gi symptoms. He did an EGD with duodenal biopsy which was negative so I am convinced I don't have celiac disease. I went back to eating gluten and developed gi symptoms and by a year later my blood pressure was back up. Whether or not this was some kind of coincidence I have no idea. At this point I saw a doctor who did functional medicine and she ordered the blood tests which showed very high levels of IGG antibody to gluten and related grains, casein, egg protein, corn syrup and ginger with a moderate reaction to soy. I cut out all foods in these groups and not only did my blood presure return to normal again, all joint pain went away and canker sores improved tremendously. I realize that this is not accepted by mainstream medicine but it works for me.
Yogaprof, the way I looked at it, mainstream medicine had not done much for me so I decided to do what I could on my own. I could control what I put in my mouth to see what happened. Cutting out gluten may deprive you psychologically but it is not going to kill you. We eat way too much gluten these days anyway. There are plenty of gluten substitutes, rice, etc that can add calories. Since you don't have celiac, you can eat oats and barley also.
10 years, many tests, 3 gi doctors, Pentasa 1000mg 3x day
diovan, simvastatin and now trying good ol' zoloft