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Internal factor Antibodies

Known as: intrinsic factor antibodies
SKU: 1373

₾165.00

Study material: Venous blood
Response time (working day): 14
The test is done on an empty stomach: no
Home call service: Yes
Country: EU

General Information

Anti-Intrinsic Factor Antibodies — This is a blood test used to diagnose pernicious anemia.

Internal factor

A glycoprotein (a complex protein containing both a polysaccharide or carbohydrate component and a protein component) that is synthesized by the parietal cells of the stomach and is an essential component for the absorption of vitamin B12 (it also participates in the absorption of other substances).

The term "intrinsic factor" was named by the American doctor William Castle, who discovered that 2 factors are involved in the formation of pernicious anemia: internal - which is produced by the parietal cells of the stomach, and external - which was later called vitamin B12.

Autoantibodies against intrinsic factor (FI) are characteristic of pernicious anemia and are found in the blood serum of 56% of patients. These antibodies are of class G and A. Only IgG is present in serum (IgA may be present in gastric juice).

Autoantibodies prevent binding of vitamin B12 to the intrinsic factor, or bind to already formed complexes (intrinsic factor + vitamin B12) and prevent its absorption.

Autoantibodies against intrinsic factor (FI) are found in a large percentage of children with juvenile pernicious anemia.

Preparation of the patient:Vitamin B2 intake should be stopped for 12 weeks before the analysis

Material for examination:Venous blood

When should we take the test?

The study is performed to confirm the diagnostics of pernicious anemia.

Possible interpretation of the results

Determination of autoantibodies against intrinsic factor (FI) is important for differential diagnostics of vitamin B12 deficiency. Megaloblastic anemia associated with low serum vitamin B12 levels and anti-intrinsic factor (FI) autoantibodies is evidence of pernicious anemia. At the same time, a negative response to antibodies does not exclude the diagnostics of pernicious anemia, since 50% of patients do not develop antibodies at all.

Reference values

Determination of autoantibodies against intrinsic factor (FI) is not recommended in patients who have been treated with injectable vitamin B12 for at least 2 weeks. Elevated levels of free vitamin B12 in the serum may be observed within 2 weeks of injection treatment, which may give a false positive response in the anti-intrinsic factor (FI) autoantibodies test. Thus, a positive result obtained in the determination of autoantibodies against intrinsic factor (FI) requires also the determination of serum vitamin B12 concentration.

In patients with autoimmune diseases, autoantibodies against intrinsic factor (FI) may be positive even without the presence of pernicious anemia.

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This medical information is not intended to be a universal treatment guide for all patients. The treatment process, including the type, volume, and frequency of diagnostic tests and therapeutic procedures, is determined by the physician individually — based on an assessment of the patient's condition and relevant medical indications. The decision is made in consultation with the patient. Before purchasing a test, please read the instructions for its preparation.
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