Pathophysiology and laboratory diagnosis of pernicious anemia

Area of Science:

• Gastroenterology
• Immunology
• Hematology

Background:

• Pernicious anemia is a hematologic condition stemming from chronic atrophic gastritis affecting stomach parietal cells.
• Autoimmune gastritis, characterized by Th1 CD4 T cell activation against gastric H/K ATPase, precedes corpus atrophy by 10-20 years.

Purpose of the Study:

• To detail the pathogenesis, clinical presentation, and diagnostic criteria of pernicious anemia and its precursor, autoimmune gastritis.
• To highlight the association of autoimmune gastritis with other autoimmune conditions.

Main Methods:

• Review of the pathophysiology of autoimmune gastritis and pernicious anemia.
• Description of diagnostic laboratory findings, including antibodies and blood counts.
• Discussion of the clinical associations of autoimmune gastritis.

Main Results:

• Autoimmune gastritis involves parietal cell antibodies targeting gastric H/K ATPase, leading to loss of intrinsic factor and HCl acid.
• Intrinsic factor loss causes cobalamin deficiency, while acid loss results in iron deficiency anemia.
• Laboratory diagnosis relies on specific antibodies, megaloblastic anemia, and elevated serum gastrin.

Conclusions:

• Pernicious anemia is a complex condition with a long preclinical phase of autoimmune gastritis.
• Accurate diagnosis requires a combination of serological markers, hematologic evaluation, and assessment of acid secretion.
• Autoimmune gastritis is linked to other autoimmune disorders, suggesting a shared underlying immune dysregulation.