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53 Cards in this Set
- Front
- Back
what's pernicious anemia?
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megaloblastic anemia
malabsorption of B12 due to IF deficiency |
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what is pernicious anemia associated w/?
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atrophic gastritis
complete achloryhdia malabsorption of B12 due to IF deficiency |
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Vit B12 description
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complex organometallic compd
(corrin ring, cobalt) cobalamin |
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source of B12?
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microorganisms
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daily dietary requirement of B12?
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2-3 ug
body stores 2-3 grams |
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what is required for B12 absorbtion?
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salivary gland and gastric "R-binders", IF and IF Receptors (lining the ileum)
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what are 2 reactions that require B12?
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1. methyltransferase to convert homocysteine to methionine (generate 5,10, methylene FH4 for DNA synth)
2. isomerize methylmalonyl CoA to succinyl CoA (??generate abnl FA's incorporated into neuronal lipids) |
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whats the order of the parts of the stomach?
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cardia, fundus, antrum
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what kind of cells are found in the fundus?
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chief cells and parietal cells
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what kind of cells secrete IF?
what else do they secrete? |
parietal
HCL |
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what's atrophic gastritis?
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1. chronic inflammation of mucosa (lymphs, plasma cells)
2. atrophy of glands (chief, parietal cells) 3. intestinal metaplasia |
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What are the most common auto-Ab's in pernicious anemia
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90% pts w/ anti-Parietal cell Ab
75% pts w/ anti-IF (blocking/binding Ab's) 50% pts have Ab's to thyroid tissue 30% pts w/ chronic thyroiditis (hashimoto) have anti-Parietal Ab and high coincidence of PA |
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where is PA most prevalent? what would a typical pt look like?
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Northern Europeans (blue eye, blond) most common
more common in males 50-80 yo |
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what are some systems that pernicious anemia affects?
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1. GI tract
2. Hematopoetic system 3. Neurological |
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What kinds of problems can PA cause in the GI tract?
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epithelial atrophy
a. atrophic glossitis-shiny glazed, depapillated tongue ("beefy") ~50% pts b. atrophic gastritis: achlorydia, gastric cancer (5%) |
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what is a "beefy" tongue associated with?
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pernicious anemia can cause atrophic glossitis--shiny, glazed depapillated tongue in about 50% of pts
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what effects does pernicious anemia have on the hematopoietic system?
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anemia, megaloblastosis
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what would you expect the bone marrow to look like in a pt w/ pernicious anemia?
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hypercellular
erythroid hyperplasia megaloblasts nuclear/cytoplasmic dyssynchrony giant metamyelocytes |
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what would you expect the peripheral smear to look like in a pt w/ pernicious anemia?
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macroovalocytes (MCV >115 fl)
hypersegmented polys giant platelets |
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what would the neuro findings be in a pt w/ pernicious anemia?
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symmetric numbness and tingling of extremitities
impaired vibratory/position sense spastic ataxia (subacute combined system dz) found in 75% pts w/ untreated PA *may occur w/o anemia |
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what causes the neuro findings associated with pernicious anemia?
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degeneration of posterior and lateral columns of SC
found in 75% untreated PA pts *may occur in absence of anemia |
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what labs would you want to test for PA?
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serum B12
Schilling test--labeled B12 to test absorption |
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how is serum B12 assessed?
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measured by radioisotope dilution assay
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what's the normal range of B12?
what range indicates deficiency? |
nl 150-650 pg/ml
deficiency seen clinically w/ levels below 100 pg/ml |
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what's a Schilling test?
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measures absorption of labeled B12
normally 10-20% excreted in 24hr urine. if less, repeat test w/ IF before oral B12. then, if excretion increased, PA likely |
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whats the treatment for PA?
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lifelong tx w/ B12
initial 1g IM, then weekly, then every month for life only 10-15% of dose retained |
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what will be seen in the blood if b12 therapy is started for PA?
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retic count rises on 3rd day then slowly declines while Hb rises
may see improvement in neuro Sx (6-12 mo), or may be permanent |
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what's the fxn of folic acid (THF)?
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intermediate in transfer of 1-carbon units (methyl):
1. synth of purines 2. synth of methionine from homocysteine 3. synth of deoxythymidylate monophosphate (DNA synth) |
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what's the result of folate deficiency?
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DNA synth impaired (like B12 def)--megaloblastosis
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what's the major clinical difference b/w PA and folate deficiency?
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no neuro defects assoc. w/ folate deficiency
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how do we get folic acid?
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entirely from our diet: green vegetables, fruits, liver
daily req: 50-200 mg |
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what's the problem w/ folate we think we're eating?
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folate very sensitive to heat/boiling--destroyed in overcooked food
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where is folate absorbed
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proximal jejunum
(B12 in terminal ileum) |
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how much folate do we have stored in our body?
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modest reserves
deficiency may arise in months w/o folate intake |
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what are the 3 major causes of folate deficiency?
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1. decreased intake
2. increased requirement 3. impaired use |
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what might cause a decrease in folate intake?
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inadequate diet (alcoholism, indigent, very old)
malabsorption (sprue, lymphoma, drugs-dilantin) |
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what might cause increased requirement for folate?
(3 "-cy's") |
pregnancy, infancy, malignancy
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what might cause impaired use of folate leading to deficiency?
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folic acid antagonists inhibit enzymes in pathway
(methotrexate, cyclophosphamide) |
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what's the most common form of a nutritional deficiency?
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iron deficiency anemia
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what are normal amounts of total body iron for men? women?
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men 6 gm
women 2 gm |
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where is iron found in the body?
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80% in Hb
storage pool: ferritin, hemosiderin |
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how is iron transported?
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transferrin
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what are nl serum Fe levels?
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men: 120 ug/dl
women: 100 ug/dl |
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what's the normal range for TIBC?
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300-350 ug
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how is iron balance regulated?
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absorption of dietary iron
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how much iron is in the typical western diet?
how much do we lose/day? how much of that is normally absorbed? |
10-20 mg of iron (heme, inorganic)
we lose about 1-2 mg/day via shedding of mucosal and skin cells about 20% absorbable--avg diet more than enough to cover loss |
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where is iron absorbed?
where does it go? |
mainly in duodenum
some immediately binds transferrin, rest bound to ferritin |
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what are 4 causes of Fe deficiency anemia?
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low diet intake (rare in US)
malabsorption (sprue) increase demand (pregnancy, infant) chronic blood loss |
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what's the most common cause of iron deficiency in the western world?
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blood loss
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what conditions increase demand of iron leading to anemia if not met (2)?
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pregnancy
infancy |
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What are some findings of Fe deficiency anemia?
(only PAGANS would lack iron) |
PAGANS:
Pallor of skin and mucous memb Atrophic Glossitis Anemia: microcytic, hypochromic Nails are Spoon-shaped |
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what are the lab findings of Fe deficiency anemia?
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Decreased:
HCT, Hb, MCV,MCHC, serum Ferritin, serum Fe Increased: TIBC |
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what else does Fe deficiency anemia cause?
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Plummer-Vinson syndrome: dysphagia, esophageal web
besides lacking iron, PAGANS don't swallow. |