An Intrinsic Factor Antibody (IF Antibody) test is ordered to diagnose the cause of Vitamin B12 deficiency. Vitamin B12 deficiency points to pernicious anaemia. Vitamin B12 is required to produce a healthy amount of red blood cells (RBCs). Intrinsic factor is a glycoprotein secreted by the cells of the stomach lining and in small quantities by the salivary glands. It binds to Vitamin B12 for its assimilation into the bloodstream. Hence, a deficiency of intrinsic factor causes a reduction in Vit. B12 resulting in pernicious anaemia. The absence of the intrinsic factor may be caused by a thinning of the lining of the stomach or some kind of removal of the stomach lining through surgery. People who follow extremely strict vegetarian diets like Veganism are also susceptible. However, the liver can store Vit. B12 for upto 5 years. Hence, diet alone cannot lead to this condition.