USMLE Forum Archives - USMLE Step 2 CK - IM 49
IM 49
TheOne - 07-14-07 18:33
A 60 years old woman consults a physician because of a 3 months history of weight loss, burning sensation of the tongue, fatigue, anorexia, and poorly localized abdominal pain. The woman appears pale to the physician. Intraoffice hematocrit is 33% with peripheral smear showing large erythrocytes and hypersegmented neutrophils. Serum folate is 2.4 ng/mL (normal greater that 1.9 ng/mL) and serum vitamin B12 is 100 pg/mL (normal 200-800 pg/mL). Stomach biopsy demonstrates chronic gastritis. Autoantibodies to which of the following are most likely involved in this patient's condition?
A. Basement membrane
B. Insulin receptor
C. Intrinsic factor
D. SS-B
E. TSH receptor
TheOne - 07-14-07 18:33
A 60 years old woman consults a physician because of a 3 months history of weight loss, burning sensation of the tongue, fatigue, anorexia, and poorly localized abdominal pain. The woman appears pale to the physician. Intraoffice hematocrit is 33% with peripheral smear showing large erythrocytes and hypersegmented neutrophils. Serum folate is 2.4 ng/mL (normal greater that 1.9 ng/mL) and serum vitamin B12 is 100 pg/mL (normal 200-800 pg/mL). Stomach biopsy demonstrates chronic gastritis. Autoantibodies to which of the following are most likely involved in this patient's condition?
A. Basement membrane
B. Insulin receptor
C. Intrinsic factor
D. SS-B
E. TSH receptor
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#3
Re: IM 49
TheOne - 08-01-07 16:30 The correct answer is C. This patient has pernicious anemia, in which autoimmune gastritis causes a lack of the intrinsic factor needed to absorb vitamin B12. Autoantibodies that are often present include those directed against the microsomal fraction of parietal cells and those capable of neutralizing intrinsic factor. The result is that vitamin B12 can no longer be absorbed by the terminal ileum. Since some vitamin B12 is stored in the liver, deficiency tends to develop slowly. Vitamin B12 deficiency can cause megaloblastic anemia; neurologic abnormalities that tend to begin with loss of position and vibration sense; and GI manifestations including anorexia, intermittent constipation or diarrhea, and abdominal pain.
Antibodies to basement membrane (choice A) are associated with Goodpasture syndrome.
Antibodies to insulin receptors (choice B) are associated with insulin resistance.
Antibodies to SS-B (choice D) occur in association with Sjögren syndrome.
Antibodies to TSH receptor (choice E) are associated with Graves disease.
#4
Re: IM 49 bingousmle - 06-20-10 07:41 these old lady probably suffers from autoimmune gastritis and pernicious anemia auto antibodies will be seen against intrinsic factor
#5
Re: IM 49 babbu5508 - 06-20-10 13:28 C. Intrinsic factor...the lady is probably suffering from pernicious anaemia due to auto antibodies to intrinsic factor..decreased absorption of vit b12
#7
Re: IM 49 babbu5508 - 06-21-10 14:20 in an atrophic gastritis, the autoimmune destruction of gastric parietal cells leads to a lack of intrinsic factor causing megaloblastic anaemia
#9
Re: IM 49 bingousmle - 06-30-10 17:44 an important association to remember is that a patient who has hypothyroidism can subsequently develop pernicious anemia as an autoimmune disorder
#10
Re: IM 49 babbu5508 - 07-10-10 03:41 Usually seated in an atrophic gastritis, the autoimmune destruction of gastric parietal cells leads to a lack of intrinsic factor and since the absorption from the gut of normal dietary amounts of vitamin B12, is dependent on intrinsic factor, the loss of intrinsic factor leads to vitamin B12 deficiency.
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