I'm sorry you have been so unwell for so long, Cheryl.   When the intestines do not absorb nutrients normally--as is seen in many cases of inflammatory bowel disease (IBD)--liver function tests, such as, alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), albumin, total protein, and total and direct bilirubin levels may become skewed due to malnutrition.   You mention that you are about to have a sigmoidoscope done. Have you discussed having a colonoscopy done, instead? With a colonoscopy, more of your GI tract can be viewed, and tissue samples can be taken for biopsy--this can not be done within the limitations of a sigmoidoscope. The trained eyes of a pathologist generally complement those of the gastroenterologist. Another suggestion is to talk to your doctor about having a video capsule endoscopy done in addition to the colonoscopy; while biopsies can not be obtained this way, just about all of the small intestine can be clearly viewed, while this is not the case with any other current exam.   IBD is not the only GI problem that could cause chronic diarrhea, and/or some of the other symptoms you've described. For instance, celiac disease, and other related disorders may be at play. Biopsies are done during the colonoscopy as the standard way of helping to make a differential diagnosis.