5 - Sideroblastic and Megaloblastic Anemia Flashcards

1
Q

size of RBCs in sideroblastic anemia

A

microcytic

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2
Q

3 general etiologies of microcytic anemias

A

iron deficiency
defects in porphyrin (sideroblastic anemia)
defects in globin - thalassemias

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3
Q

sideroblastic anemias are due to defects in

A

porphyrin ring

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4
Q

ringed sideroblast

A

pathologic finding in bone marrow - large blocks of iron stained with Prussian Blue indicating buildup of iron since porphyrin is defective and can’t incorporate it

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5
Q

key histo finding in sideroblastic anemia

A

RINGED sideroblast (plain sideroblasts are normal)

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6
Q

congenital sideroblastic anemia inheritance pattern

A

most often x linked, but can also be autosomal recessive or mitchondrial

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7
Q

relationship between congenital sideroblastic anemia and porphyrias

A

both are defects in porphyrin synthesis - sideroblastic anemia is defect in first step, porphyrias are in later steps and produce backup of toxic intermediates

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8
Q

enzyme deficient in congenital sideroblastic anemia

A

delta aminolevulinic acid synthase (delta ALA synthase)

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9
Q

some pts with congenital sideroblastic anemia improve when given ___ because ___

A

pyridoxine, it is a cofactor of the deficient enzyme

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10
Q

causes of acquired sideroblastic anemia (5)

A
alcohol (depletes pyridoxine)
lead
copper deficiency (2/2 past gastric bypass, zinc in denture adhesives; also presents w/ peripheral neuropathy)
INH (TB drug)
chloramphenicol
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11
Q

what clue can you see in PBS in pt w/ lead induced sideroblastic anemia?

A

coarse basophilic stipling (fine basophilic stipling could just be a retic)

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12
Q

acquired sideroblastic anemia can also be a part of what syndrome?

A

myelodysplastic syndrome

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13
Q

blood work findings in acquired sideroblastic anemia as part of myelodysplastic syndrome:
serum iron?
% sat w/ iron?
ferritin?

A

inc serum iron
inc % sat
high ferritin

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14
Q

general tx of siderblastic anemia

A

pyridoxine, transfusions if severe

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15
Q

why would the MCV in acquired sideroblastic anemia not be low?

A

often have 2 distinct populations of cells - micro and macrocytic, average out to normal-ish MCV

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16
Q

mechanism behind megaloblastic anemia

A

DNA synth impaired > arrest cell division while cytoplasm continues to grow > macrocytosis

17
Q

main causes (2) of megaloblastic anemia

A

B12 and folate deficiency

18
Q

other findings in PBS with megaloblastic anemia (besides macrocytosis) (3)

A

hypersegmented neutrophils
oval shaped cells
Howell Jolly bodies (small basophilic spot in mature erythrocyte)

19
Q

cobalamin (B12) deficiency results in increase in ____ and ____ (chemicals)

A

methylmalonic acid and homocysteine

20
Q

absorption of B12

A

binds to haptocorrin (from saliva) in stomach
GIF (from parietal cells) grabs B12 in duodenum
absorbed in ileum
B12 exported into plasma and binds transcobalamin

21
Q

absorption of B12 is inhibited by what common drug?

A

metformin

22
Q

pernicious anemia

A

autoimmune attack on parietal cells
also get blocking anti GIF antibodies
decreased B12 absorption

23
Q

clinical manifestations of B12 deficiency

A
megaloblastic anemia (ineffective erythropoiesis and increased apoptosis)
thrombocytopenia
leukopenia
cardiomyopathy
pale "lemon yellow" skin
gastric atrophy / CA
glossitis
combined systems degeneration
24
Q

lab values indicating b12 deficiency

A
inc LDH
low haptoglobin
inc MMA, homocysteine
serum iron often inc
TIBC normal, % sat inc
ferritin inc
25
Q

main way to tell B12 deficiency from folate clinically

A

folate has no neuro sx

26
Q

causes of folate deficiency

A
nutritional
dialysis
celiac
gastric bypass
IBD
pregnancy
hemolysis
drugs/ETOH
27
Q

main way to tell B12 deficiency from folate from bloodwork (other than just measuring vitamin levels..)

A

folate > inc homocysteine

B12 > inc homocysteine AND MMA

28
Q

less common causes of megaloblastic anemia

A

nitrous oxide
drugs (methotrexate, hydroxyurea, DNA synth inhibitors, anti convulsants, oral contraceptives)
inborn errors of metabolism
myelodysplastic syndrome