Anti-parietal cell antibody (APCA)

What sample is needed for Anti-parietal cell antibody (APCA)?

1. Venous blood is needed to prepare the serum.
2. The patient’s serum is needed and should be stored at -20 °C.
   • How to get good serum: Take 3 to 5 ml of blood in a disposable syringe or a vacutainer. Keep the syringe for 15 to 30 minutes at 37 °C and then centrifuge for 2 to 4 minutes to get the clear serum.

What are the indications for Anti-parietal cell antibody (APCA)?

• This antibody test is done to diagnose the autoimmune type of Pernicious anemia.

What are the precautions for Anti-parietal cell antibody (APCA)?

• APCA is present in many healthy persons over the age of 60 years.

How will you discuss the pathophysiology of Anti-parietal cell antibody (APCA)?

1. The parietal cells are present in the proximal portion of the gastric mucosa and produce acid (HCL) and Intrinsic factors.
2. The intrinsic factor is needed for the absorption of vit B12.
3. A lack of an intrinsic factor due to the antiparietal cell antibodies (APCA) will lead to pernicious anemia.
4. These antiparietal cell antibodies lead to the destruction of the gastric mucosa.

5. Parietal cell antibodies occur in patients with pernicious anemia (50% to 100%).
6. There will be a disruption (no production) of the intrinsic factor by the parietal cells.
7. In pernicious anemia, two types of antibodies were found:
   1. One against the parietal cells.
   2. Second, against the intrinsic factor.

8. This antibody can be seen in other autoimmune diseases (20% to 30%), such as Thyroiditis, myxedema, juvenile diabetes, Addison’s disease, and iron-deficiency anemia.

How will you discuss Anti-parietal cell antibodies (APCA)?

1. These are 95% positive in cases of Pernicious anemia (another reference says 76% to 91%).
   1. The normal population has 10% to 15% of these antibodies.
   2. This is nonspecific to the IF antibody.
2. With increasing age, the incidence of APCA increases, especially in the relatives of pernicious anemia patients.
3. In pernicious autoimmune anemia, antiparietal antibodies are >80% positive; 50% have antibodies to intrinsic factors.
4. Antiparietal antibodies are seen in healthy adults >60 years of age.
5. Sometimes these antiparietal antibodies are seen in:
   1. Atrophic gastritis (idiopathic atrophic gastritis shows 30% to 60% APCA.
   2. Gastric ulcer.
   3. Gastric malignancies.
   4. Juvenile diabetes mellitus.
   5. Iron-deficiency anemia.
   6. Myxedema.
   7. Thyroiditis.
   8. Addison’s disease.
6. APCA, when positive, then needs a more invasive procedure like a gastric biopsy to rule out a gastrointestinal disease.

What are the other possibilities of APCA in various diseases?

What are the normal antiparietal cell antibodies?

• These are normally negative.

Source 4

• Negative anti-parietal antibody by IFA technique.
  • When positive, then titrate the serum.
  • Positive = Titer level of 1:240

What are the positive possibilities of Anti-parietal cell antibody (APCA)?

1. Pernicious anemia (in 95% of the cases, although its specificity is low).
2. Atrophic gastritis (30% to 60%).
3. Gastric cancer and gastric ulcer.
4. These are present in 25% to 30% of the autoimmune diseases of the thyroid.
   1. Hashimoto’s thyroiditis (25%).
   2. Myxedema.
   3. Thyrotoxicosis (25% to 35%)
5. Juvenile diabetes (12% to 28%).
6. Addison disease.
7. Iron deficiency anemia.
8. A normal person (5% to 10%).

What are the causes of increased Anti-parietal cell antibody (APCA)?

1. Pernicious anemia.
2. Atrophic gastritis.
3. Myxedema.
4. Hashimoto’s thyroiditis.
5. Juvenile diabetes.
6. Addison disease.

Questions and answers: