<<Disclaimer: Verify this information before applying it to your situation.>> In reading through literature on Celiac disease, I have encountered not only IgA deficiency, but also low C3 and C4 levels. These complements are necessary for the making of antibodies in human subjects. Furthermore, all hormone, enzyme and immunoglobulin manufacture would be adversely affected by a longstanding malnutrition situation. I also just read a post that spleen function may be impaired, as well. All of these have profound effects on the proper functioning of the immune system. Indeed, I personally have had depressed C3, C4, as well as immunoglobulins, such as IgG and IgM. My question is regarding the logic of medical diagnostics. How can we use tests that depend upon a properly functioning immune system to prescreen for a disease that might depress the very system upon which the test depends? Isn't this illogical? Specifically, why do they insist upon anti-endomysial antibodies, in a person who may be unable to manufacture antibodies at a level high enough to test? The sickest people are the most likely to not measure proper antibody levels. Joanne