Intrinsic Factor Antibody Test
You should wait at least 48 hours after receiving a vitamin B12 injection to have a blood sample taken. The doctor may prefer not to draw a blood sample for the test within 2 weeks of an injection. Intrinsic factor (IF), also known as gastric intrinsic factor (GIF), is a glycoprotein produced by the parietal cells of the stomach. Intrinsic factor is required for the absorption of vitamin B12 (cobalamin) from the small intestine. When enough Vitamin B12 is not absorbed, it leads to anaemia. Intrinsic Factory Antibody is not a very commonly ordered test and is usually ordered in cases of suspected anaemia and along with Serum Iron Studies. Signs and symptoms of anaemia include paleness, weakness, fatigue, numbness and a CBC (complete blood count or heamogram) reveals abnormality in Red Blood Cells.
In pernicious anemia, which is most commonly an autoimmune disease, autoantibodies directed against intrinsic factor or parietal cells themselves lead to an intrinsic factor deficiency, mal-absorption of vitamin B12, and subsequent megaloblastic anaemia.
Atrophic gastritis (severe inflammation of the stomach lining) can also cause intrinsic factor deficiency and anaemia through damage to the parietal cells of the stomach wall. Pancreatic exocrine insufficiency can interfere with normal dissociation of vitamin B12 from its binding proteins in the small intestine, preventing its absorption via the intrinsic factor complex.
When a person has a decreased vitamin B12 level and increased methylmalonic acid and homocysteine levels, an intrinsic factor antibody test is typically ordered.
|Related Tests||Parietal Cell Antibody, Vitamin B12, Complete Blood Count, Blood Smear, Homocysteine|