Clinical features:
(1) age of the patients is usually > 50 years of age
(2) type A atrophic gastritis with intestinal metaplasia, primarily affecting the body of the stomach, with relative sparing of the gastric antrum
(3) achlorhydria unresponsive to stimulation
(4) variable presence of other autoimmune disorders (Hashimoto's thyroiditis, etc.)
(5) neurologic complications of vitamin B12 deficiency
(6) atrophic glossitis
Laboratory features:
(1) autoantibodies
(1a) antiparietal cell antibodies
(1b) anti-intrinsic factor antibodies
(2) hypergastrinemia
(3) pancytopenia with megaloblastic anemia and hypersegmented neutrophils
(4) decreased serum levels of pepsinogen I (PGI)
(5) decreased serum vitamin B12
(6) increased urinary excretion of methylmalonic acid
