I was tested once for celiac disease and it came back negative. in three years could that have changed?

Yes: Celiac disease is an IgA (antibody) mediated disease that can be tested through blood work. But a definitive diagnosis is best obtained through a biopsy sample taken during an endoscopic GI procedure. Hope this helps.

Check with you Doc: Discuss with your doctor why your were tested for celiac disease. As with any test, the degree of suspicion for a particular disease helps understand the results. If there was a very high index of suspicion for celiac disease and the test was negative it may need to be repeated or further testing may need to done like a biopsy of your small intestine.

Simple answer=yes: There is the day,month or year before you get any problem.With a problem like CD, you can be born with a tendency toward developing the disease, but you are not born with it. At some point, you experience the event or events that trigger a change and begin to develop antibodies to gluten based proteins.These then begin to attack gut tissues. So yes this can change in three years.