When I had my very first colonoscopy, which is when my rectal tumor was found, my GI was trying to find out why I had constant bowel issues. He took numerous biopsies to rule things out such as celiac disease. If you are having a colonoscopy anyway, have them do a biopsy for celiac. The blood test is a screening tool, but only a biopsy can confirm the diagnosis.
Just an idea....
Dx Feb 2010 4 cm tumor, just inside rectum
EUS stated T3 tumor
2nd opinion, need better path
Mar 2010 transanal surgery. Surgery by board certified CRS found tumor only in lining
6 exams of surg site, 3 PET, 3 scopes laterNED.
Scope in Mar2015, clean colon
Next scope/test in 3 years