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18 Cards in this Set
- Front
- Back
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what is/are the most common cause(s) of megaloblastic anemia?
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vitamin B12 and folate deficiency
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where do we get B12 from?
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only animal products so vegetarians are susceptible to developing B12 deficiency
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what is the cofactor that is needed for B12 to be absorbed? where does it come from?
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- intrinsic factor
- made and released by parietal cells of the stomach |
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what is the function of B12 in the body?
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B12 is a cofactor for the conversion of
1) homocysteine to cysteine 2) methlymalonyl-CoA to succinyl-CoA |
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what is the result of a vitamin B12 deficiency?
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pernicious anemia
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what are the 2 ways we can develop pernicious anemia?
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1) autoimmune attack on gastric intrinsic factor
2) chronic gastritis leads to autoantibodies against gastric parietal cells causing the destruction of parietal cells and decreased production of intrinsic factor |
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what are the 2 main findings from a bone marrow aspirate in patients with pernicious anemia?
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- megaloblastic (large) erythrocytes
- hypersegmented neutrophils (> 5 lobes) |
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a 55 year old patient comes in complaining of fatigue. physical exam shows icterus, atrophic glossitis, and a shuffling broad gait. Labs show increased MCV, decreased Hb, and increased LDH and bilirubin levels. what is the most likely diagnosis?
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- pernicious anemia (B12 deficiency)
folate deficiency labs will present the same, but a patient only has neurological symptoms with B12 deficiency |
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where in the bowel is folate absorbed?
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jejunum
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what is the normal function of folate in the body?
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a cofactor in the conversion of homocysteine to cysteine
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what is a normal serum B12 level? what is a normal serum folate level?
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- > 300 pg/ml
- > 4 mg/ml |
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a patient with anemia has increased levels of MMA and increased levels of homocysteine. what is the most likely diagnosis?
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definitely a B12 deficiency
possibly a folate deficiency |
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a patient with anemia has normal MMA levels and increased homocysteine levels. what is the most likely diagnosis?
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folate deficiency.
a B12 deficiency is possible but a person's folate can be depleted much faster than their B12 so it is most likely a folate deficiency |
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a patient with anemia has normal MMA levels and normal homocysteine levels. what is the most likely diagnosis?
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not sure but this definitely rules out B12 deficiency.
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what are the side effects or consequences of giving too much B12 or folate as therapy for a deficiency?
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none; both are inexpensive, nontoxic, and excess amounts are readily excreted harmlessly in the urine
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you see a patient and diagnose vitamin B12 deficiency. you put the patient on B12 supplements. you see the patient every 2 weeks for the next 3 months. after 3 months their anemia is not any better. what is most likely happening?
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- it is most likely that the patient is not taking the B12 regularly. however, if a patient fails to recover from either B12 or folate deficiency after 2 months and they are taking the meds then you need to re-think the diagnosis
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what is a major concern early on during treatment for either B12 or folate deficiency?
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hypokalemia; the patient is using lots of K in making new RBCs
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do the neurologic symptoms that can be associated with B12 deficiency always improve?
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no
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