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53 Cards in this Set

  • Front
  • Back
what's pernicious anemia?
megaloblastic anemia
malabsorption of B12 due to IF deficiency
what is pernicious anemia associated w/?
atrophic gastritis
complete achloryhdia
malabsorption of B12 due to IF deficiency
Vit B12 description
complex organometallic compd
(corrin ring, cobalt)
cobalamin
source of B12?
microorganisms
daily dietary requirement of B12?
2-3 ug

body stores 2-3 grams
what is required for B12 absorbtion?
salivary gland and gastric "R-binders", IF and IF Receptors (lining the ileum)
what are 2 reactions that require B12?
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)
whats the order of the parts of the stomach?
cardia, fundus, antrum
what kind of cells are found in the fundus?
chief cells and parietal cells
what kind of cells secrete IF?

what else do they secrete?
parietal

HCL
what's atrophic gastritis?
1. chronic inflammation of mucosa (lymphs, plasma cells)
2. atrophy of glands (chief, parietal cells)
3. intestinal metaplasia
What are the most common auto-Ab's in pernicious anemia
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
where is PA most prevalent? what would a typical pt look like?
Northern Europeans (blue eye, blond) most common
more common in males
50-80 yo
what are some systems that pernicious anemia affects?
1. GI tract
2. Hematopoetic system
3. Neurological
What kinds of problems can PA cause in the GI tract?
epithelial atrophy

a. atrophic glossitis-shiny glazed, depapillated tongue ("beefy") ~50% pts

b. atrophic gastritis: achlorydia, gastric cancer (5%)
what is a "beefy" tongue associated with?
pernicious anemia can cause atrophic glossitis--shiny, glazed depapillated tongue in about 50% of pts
what effects does pernicious anemia have on the hematopoietic system?
anemia, megaloblastosis
what would you expect the bone marrow to look like in a pt w/ pernicious anemia?
hypercellular
erythroid hyperplasia
megaloblasts
nuclear/cytoplasmic dyssynchrony
giant metamyelocytes
what would you expect the peripheral smear to look like in a pt w/ pernicious anemia?
macroovalocytes (MCV >115 fl)
hypersegmented polys
giant platelets
what would the neuro findings be in a pt w/ pernicious anemia?
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
what causes the neuro findings associated with pernicious anemia?
degeneration of posterior and lateral columns of SC

found in 75% untreated PA pts

*may occur in absence of anemia
what labs would you want to test for PA?
serum B12

Schilling test--labeled B12 to test absorption
how is serum B12 assessed?
measured by radioisotope dilution assay
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
what's a Schilling test?
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
whats the treatment for PA?
lifelong tx w/ B12

initial 1g IM, then weekly, then every month for life
only 10-15% of dose retained
what will be seen in the blood if b12 therapy is started for PA?
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
what's the fxn of folic acid (THF)?
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)
what's the result of folate deficiency?
DNA synth impaired (like B12 def)--megaloblastosis
what's the major clinical difference b/w PA and folate deficiency?
no neuro defects assoc. w/ folate deficiency
how do we get folic acid?
entirely from our diet: green vegetables, fruits, liver

daily req: 50-200 mg
what's the problem w/ folate we think we're eating?
folate very sensitive to heat/boiling--destroyed in overcooked food
where is folate absorbed
proximal jejunum

(B12 in terminal ileum)
how much folate do we have stored in our body?
modest reserves

deficiency may arise in months w/o folate intake
what are the 3 major causes of folate deficiency?
1. decreased intake
2. increased requirement
3. impaired use
what might cause a decrease in folate intake?
inadequate diet (alcoholism, indigent, very old)

malabsorption (sprue, lymphoma, drugs-dilantin)
what might cause increased requirement for folate?

(3 "-cy's")
pregnancy, infancy, malignancy
what might cause impaired use of folate leading to deficiency?
folic acid antagonists inhibit enzymes in pathway
(methotrexate, cyclophosphamide)
what's the most common form of a nutritional deficiency?
iron deficiency anemia
what are normal amounts of total body iron for men? women?
men 6 gm
women 2 gm
where is iron found in the body?
80% in Hb

storage pool: ferritin, hemosiderin
how is iron transported?
transferrin
what are nl serum Fe levels?
men: 120 ug/dl
women: 100 ug/dl
what's the normal range for TIBC?
300-350 ug
how is iron balance regulated?
absorption of dietary iron
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
where is iron absorbed?

where does it go?
mainly in duodenum

some immediately binds transferrin, rest bound to ferritin
what are 4 causes of Fe deficiency anemia?
low diet intake (rare in US)
malabsorption (sprue)
increase demand (pregnancy, infant)
chronic blood loss
what's the most common cause of iron deficiency in the western world?
blood loss
what conditions increase demand of iron leading to anemia if not met (2)?
pregnancy
infancy
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
what are the lab findings of Fe deficiency anemia?
Decreased:
HCT, Hb, MCV,MCHC, serum Ferritin, serum Fe

Increased:
TIBC
what else does Fe deficiency anemia cause?
Plummer-Vinson syndrome: dysphagia, esophageal web

besides lacking iron, PAGANS don't swallow.