Pernicious Anemia: Early Detection of the Historical “Great Pretender"

Abstract

Pernicious anemia (PA) is the late manifestation of autoimmune metaplastic atrophic gastritis (AMAG) characterized by the presence of anti-intrinsic factor with eventual decreased absorption of cyanocobalamin. Various clinical manifestations from subtle anemia to serious neurological symptoms gives PA notoriety as a “great pretender”. We present a case of an asymptomatic patient who was found to have severe gastritis with anemia leading to further evaluations revealing a chronic autoimmune disorder. A 52-year-old female with history of HTN, abnormal uterine bleeding, DM2 and anemia presented with abnormal labs. Colonoscopy completed 6 years ago for iron deficiency anemia found no etiology. Labs revealed Hb 6.0g/dl, Hct 17.5%, Plt 140,000/uL, MCV 114, RDW 27.2%, Iron 108μg/dL, ferritin 338ng/ml. Iron Saturation 32%, transferrin 258mg/dL, TIBC 335μg/dL, vitamin B12 <50pg/mL, Folate 22.8ng/mL, vitamin D 25-OH 13ng/mL. Fecal occult blood test was negative.EGD was performed to screen for (PA) and gastric malignancies which revealed frank blood in the gastric fundus, friable gastric mucosa, and erythematous mucosa in the pylorus. Pathology was consistent with autoimmune gastritis. Intrinsic factor antibody assay was positive. She was started on Cyanocobalamin injections, and continued on lifelong B12 supplementation. PA accounts for 20-50% of all cobalamin deficiencies in adults, and it is a complex disorder associated with hematological, gastric, immunological and neurological alterations. It has a prevalence 0.1% in the general population and is diagnosed in up to 15-25% of patients with AMAG. Disease progression includes symptoms ranging from fatigue and weakness, to atrophic glossitis, to more severe peripheral neuropa thies and subacute combined degeneration. Increase in MCV and hypersegmented neutrophils are usually the initial laboratory findings. This case illustrates the need to have early detection and timely treatment of PA induced vitamin B12 deficiency. Vitamin D displays immunomodulatory properties may be a risk factor. One case-control study revealed levels of vitamin D in autoimmune gastritis patients were significantly lower than in the general population. Evaluation by EGD and histopathology of AMAG is necessary due to its precancerous nature. Gastric carcinoid tumors have been observed in 4-9% of patients with AMAG and PA so continued surveillance should always remain a part of the patient's plan of care.2036_A Figure 1. Upper GI Bleed2036_B Figure 2. Gastritis2036_C Figure 3. Friable Gastric Mucosa