and diarrhea), dry skin, chronic fatigue, depression, irritability, brain fog, hair loss, Graves disease, low nutrient levels, weight gain
(as well as weight loss), anemia (pernicious or otherwise) are all frequently associated with celiac disease. I would hope that no one experiences all symptoms of celiac or they would be a miserable wreck. Nonetheless, some do get a larger share than others. Your symptoms certainly warrant testing for celiac disease, both blood and biopsy.
Nonetheless, it is possible to have all these same symptoms and not have celiac disease, but still be intolerant of gluten -- what is known as non-celiac gluten intolerance (NCGI) for which there is no current testing available (in fact it was only recognized within the last year or two as a real medical condition). As for the accuracy of the testing, there are very few false positives, but about a 20% false negative rate. It is important to run the entire celiac panel:
Anti-Gliadin (AGA) IgA
Anti-Gliadin (AGA) IgG
Anti-Endomysial (EMA) IgA
Anti-Tissue Transglutaminase (tTG) IgA
Deamidated Gliadin Peptide (DGP) IgA and IgG
Total Serum IgA
because you may test positive on some and negative on others. Only one positive is needed for the diagnosis. The total serum IgA is a control test to validate the other results (ensuring you are a normal IgA producer).
As for the biopsy, the small intestine is a very large area and the endoscope cannot reach most of it. So your celiac must be within reach of the scope, if it is in early stages and damage is not yet visible to the naked eye, you must hope that you are lucky and can make your doctor take enough samples (at least 6-8) to have a chance of finding it. Then you must hope that the pathologist is experienced in reading celiac slides. So yes, there are unfortunately false negatives in biopsies too.
Generally speaking you will be advised by members of this board (and by more and more doctors) that even if you test negative you should give the gluten free diet a three-month strict trial at least, and see if you notice any difference in your symptoms. You should also be tested for vitamin levels, especially b!2 which you have already covered, D, folate, and minerals potassium, magnesium, calcium, zinc and ferritin.
Welcome to the board, and do feel free to question away
"Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted." - Albert Einstein
"Life is not weathering the storm; it is learning to dance in the rain"
"Whatever the question, the answer is always chocolate." Nigella Lawson
Caffeine free 1973
Lactose free 1990
(Mis)diagnosed IBS, fibromyalgia '80's and '90's
Diagnosed psoriatic arthritis 2004
Self-diagnosed gluten intolerant, gluten-free Nov. 2007
Soy free March 2008
Nightshade free Feb 2009
Citric acid free June 2009
Potato starch free July 2009
(Totally) corn free Nov. 2009
Legume free March 2010
Now tolerant of lactose
Celiac.com - Celiac Disease