Test Details: Intrinsic factor antibody test is done to diagnose pernicious Anemia, most common cause of vitamin B12 deficiency. Symptoms include Anemia, neuropathy, numbness, tingling, pain and weakness in the affected area. Intrinsic factor antibodies are protein produced by the immune system that are associated with pernicious Anemia. Symptoms include pale skin, weakness, fatigue, numbness, tingling etc.