autoimune gastritis

Question 1

most common cause of chronic gastritis

Answer 1

H pylori

Question 2

other cause of chronic gastritis

Answer 2

autoimmune gastritis (10%)

Question 3

mechanism of autoimmune gastritis

Answer 3

autoreactive CD8+ T cells destroy parietal cells and CD4+ T cells against proton pump (Type IV)

autoantibodies against parietal proton pump (Na/H ATPase) and intrinsic factor (Type II)

breakdown of tolerance
HLA-B8 and HLA-DR3
H pylori infection can induce autoimmunity - reveals self antigens

Question 4

clinical presentation:

Answer 4

loss of parietals - decreased gastric acid (achlorhydria)

stimulates gastrin release (G cell hyperplasia)

insufficient iron absorption (which requires acidic pH)

decreased intrinsic factor (pernicious anemia/Vit D deficiency)

some chief cell destruction (decreased serum pepsingogen)

Question 5

histo changes

Answer 5

atrophic and metaplastic changes of parietal cells of gastric body and fundus (spares antrum)

inflammation

G cell and ECL cell hyperplasia (ECL –> histamine –> parietal cell –> acid)

loss of chief cells

intestinal metaplasia - goblet cells and columnar absorptive cells in the stomach

Question 6

symptoms

Answer 6

GI - dyspepsia, early satiety, melena possible

iron deficiency

B12 deficiency –> pernicious anemia –> weakness, LH, palpitations, sore and red tongue (atrophic glossitis),n diarrhea, constipation, abnormal sensation, general cognitive/mood changes

Question 7

Dx

Answer 7

endoscopy with biopsy (body and fundus)
CBC to check for anemia and decreased serum B12, elevated serum gastrin and decreased pepsinogen
anti intrinsic and parietal cell antibodies

Question 8

Tx

Answer 8

iron and B12 supplements
anti-inflammatories