I went to the specialist endo guy thinking it was the thyroid issue (I was misdiagnosed by a nitwit and by the time it was figured out--it was too late to reverse) and it telling him about both abdominal surgeries and losing 8 lbs in 3 days for no reason (3 times) he nailed it and said to see a gastroenterologist, which I did--I told him my symptoms and it was determined that it was most likely malabsorption (I get bloodwork done 2-3 times a year and the doctors have access to the results) which were pretty much all normal except for the thyroid thing--so he said to try the Creon--and I did put on 7-8 pounds and maintain that. I don't know what tests they do--but I was never told I needed them. I have read (online) that having abdominal surgeries sometimes do result in malabsorption.