The varieties of language you use in different areas of your life are known as speaking or writing styles. Some particularly specialized styles, such as those used in the courtroom, or poetry, or the operating room, are known as registers.
The United States National Institutes of Health recommends testing vitamin A levels in people with celiac disease at diagnosis. This is because vitamin A deficiency is common in celiac disease. Deficiency can result from incomplete digestion, absorption, or metabolism. Normal absorption of vitamin A first requires digestion, or releasing, from food protein in the stomach.
Malabsorption of nutrients, like iron, is common for individuals with celiac disease, and there is a high occurrence of anemia (up to 33%) in celiac disease patients. The relationship is so strong, in fact, that people whose anemia has no obvious cause (i.e. blood loss) should be tested for celiac disease.