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Folate and B12 Metabolism Deficiency Flashcards

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3965781771What was the historic "extrinsic factor"?Vit B120
3965781772What is cobalamin and coenzyme B12?Both are names for Vit B121
3965781773Where is Vit B12 made?by microorganisms2
3965781774What are the dietary sources of Vit B12?liver, glandular tissue, muscle, eggs, diary products, seafood3
3965781775What is the body storage level of Vit B12? How much is used daily?stores 2-5 mg, and use 2-5 ug (0.1%)4
3965781776Where is B12 absorbed?only in the terminal ileum5
3965781777What two reactions does Vit B12 mediate?(1) methyl transfer: methylation of homocystein to generate methionine. crucial for dividing tissues (like blood cell progenitors) (2) hydrogen transfer: generation of succinyl coA , crucial for myelin maintenance (explains neurological symptoms)6
3965781778What is the most frequent cause of B12 deficiency?malabsorption: due to salivary gland dysfunction, loss of intrinsic factor (gastric), pancreatic disease, terminal ileum illness, IBS7
3965781779Can B12 deficiency be caused by congenital deficiency states or inadequate ingestion?yes, but it is very rare8
3965781780What are the 3 main clinical features of pernicious anemia?Gastric atrophy (no folds), megaloblastic anemia, neurological degeneration (demyelenation)9
3965781781What does the bone marrow of pernicious anemia pts look like?huge bone marrow cells - megaloblasts10
3965781782What would a CBC and blood smear reveal with pernicious anemia?hemolysis because megaloblasts are dying in the bone marrow, thrombocytopenia, leukopenia,11
3965781783What clinical/lab findings are specific to Vit B12 deficiency?low serum B12 levels (<200) Peripheral and central nervous system disease methylmalonic acidemia elevated gastric pH12
3965781784What's the difference between TC1 and TCII B12?TC II B 12 -- is biologicallly useful! TCII can have a B12 analogue, though TCI can't be absorbed.13
3965781785Under what conditions can serum B12 levels read falsely normal?intestinal bacterial overgrowth, liver disease, myeloid disorders14
3965781786Under what conditions can serum B12 be falsely low?pregnancy, lymphoid disorders, ageing, racial differences15
3965781787What is the most reliable marker for Vit B12 deficiency?MMA (methylmalonic acid)16
3965781788What is the therapy for Vit B12 deficiency?B12 injections monthly for a lifetime17
3965781789T/F: there can be lots of variation in the presence of neurologic manifestations with Vit B12 deficiency.true18
3965781790What is Tropical Macrocytic anemia?an anemia identical to B12 deficiency but not associated with atrophic gastritis or neurologic disease19
3965781791What synthesizes folic acid?higher plants and microorganisms20
3965781792How much folic acid do you store? How much do you use daily? Where is folate stored?store 5 mg and use about 50 ug. Both folate and Vit B12 are stored in the liver21
3965781793What are some dietary sources of folate?leafy greens, asparagus, broccoli, spinach, liver, kidney, fruits, mushrooms22
3965781794How folic acid transformed, from the time it enters the body?dietary folate is mostly in methylated form. it is deconjugated in the intestine before absorption. It is reduced to N5-methyl tetrahydrofolate (FH4), and once in the tissues, it is polyglutamated23
3965781795How do folate and Vit B12 interface?Vit B12 is there to allow methioniine syntase to convert 5-methyl TH4 folate to TH4 folate24
3965781796What are the consequences of folate deficiencies?poor DNA synthesis. Get uracil misincorporation into DNA, leading to DNA strand breaks and cell cycle arrest... that is why you get macrocytosis.25
3965781797Is folate deficiency anemia micro or macrocytic?macrocytic, because of problem with DNA synthesis, and those cells being stuck in that phase of the cell cycle26
3965781798T/F: both folate and B12 deficiency result in systemic disease and neuropathyfalse! neurological disorders result from B12, not folate, deficiencies27
3965781799What are the causes of folate deficiency?inadequate ingestion (very common), inadequate absorption, metabolic block in utilization, increased requirement28
3965781800How do you assess short term folate levels? Long term folate levels?Short term : serum folic acid levels (< 3 ng/mL is bad) Long term/chronic: red cell folate levels (<135 ng/mL is bad)29
3965781801Besides folate levels, what other metabolite can suggest folate deficiency?high levels of homocysteine... but how elevated matters (normal is 4-12... for folate deficiency its 15-50, and for B12 deficiency its 20 - 241)30
3965781802B12 or folate deficiency: megaloblastic anemia?both31
3965781803B12 or folate deficiency: combined system degeneration?B1232
3965781804B12 or folate deficiency: poor diet associated with deficiency state?B12 - rare; folate - common33
3965781805B12 or folate deficiency: other dietary deficiencies present?folate34
3965781806B12 or folate deficiency: dietary source?B12: muscle, liver, milk, eggs Folate: liver, leafy greens35
3965781807B12 or folate deficiency: deficiency induces high homocystein?both36
3965781808B12 or folate deficiency: site of absorption?B12: terminal ileum folate: all small bowel37
3965781809B12 or folate deficiency: intrinsic factor required?B1238
3965781810B12 or folate deficiency: deficiency associated with high methylmalonic?B12 only39

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