Gastrointestinal · Year 2 · from Gastrointestinal
Case 3: Autoimmune Gastritis with Pernicious Anemia
Patient Presentation
Demographics: 55-year-old female
Chief Complaint: Progressive fatigue, tingling in feet, and glossitis for 8 months
History of Present Illness: The patient describes worsening fatigue that limits her daily activities. She has noticed tingling and numbness starting in her toes and progressing up her feet. Her tongue has been sore and appears smooth. She has had intermittent episodes of loose stools. She denies weight loss, abdominal pain, or blood in stool.
Past Medical History: Hashimoto's thyroiditis (on levothyroxine), vitiligo
Family History: Mother had "thyroid problems" and anemia requiring injections
Physical Examination
- Vital Signs: BP 118/70 mmHg, HR 92 bpm
- General: Pale female with visible vitiligo patches
- HEENT: Smooth, beefy-red tongue (atrophic glossitis); pale conjunctivae
- Cardiac: Mild tachycardia, systolic flow murmur
- Neurologic: Decreased vibration sense in feet, diminished position sense in toes
- Skin: Depigmented patches on hands and face (vitiligo)
Workup and Results
- CBC: Hemoglobin 8.4 g/dL, MCV 122 fL (macrocytic), WBC 3.4, Platelets 145
- Peripheral Smear: Macro-ovalocytes, hypersegmented neutrophils
- Vitamin B12: 88 pg/mL (severely low)
- Methylmalonic Acid: Markedly elevated
- Fasting Gastrin: 1,250 pg/mL (elevated due to achlorhydria)
- Anti-Parietal Cell Antibodies: Positive
- Anti-Intrinsic Factor Antibodies: Positive
- Upper Endoscopy: Atrophic mucosa limited to gastric body and fundus; antrum normal; small polyps in body
Endoscopic appearance of autoimmune atrophic gastritis showing pale, thin mucosa in the gastric body with loss of normal rugal folds and visible submucosal vessels, contrasting with normal antral mucosa.
Image Source: Case courtesy of Radiopaedia.org
Diagnosis
Autoimmune Gastritis (Type A Gastritis) with Pernicious Anemia
Clinical Correlation
Autoimmune gastritis is characterized by autoantibodies targeting parietal cells and intrinsic factor, leading to destruction of acid-secreting cells in the gastric body and fundus. This results in: (1) achlorhydria - loss of acid production; (2) intrinsic factor deficiency - causing B12 malabsorption and pernicious anemia; (3) hypergastrinemia - loss of acid-mediated feedback inhibition of G cells; (4) ECL cell hyperplasia - from chronic gastrin stimulation, with potential for carcinoid tumors. The condition associates with other autoimmune diseases (thyroiditis, vitiligo, type 1 diabetes). Neurologic manifestations (subacute combined degeneration) result from B12 deficiency affecting myelin synthesis.
Treatment
- Intramuscular vitamin B12 (cyanocobalamin) 1000 mcg daily for 7 days, then weekly for 4 weeks, then monthly lifelong
- Monitor for hypokalemia during early treatment
- Surveillance endoscopy for gastric carcinoid tumors and adenocarcinoma
- Monitor chromogranin A levels
- Screen for concurrent autoimmune conditions
- Family screening for autoimmune gastritis