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clin med IV > macrocytic anemias > Flashcards

macrocytic anemias Flashcards

1
Q

what is a macrocytic anemia

A
  • retic are big
  • grouped as megaloblastic vs macrocytic
  • > 100 MCV vs > 115 MCV
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2
Q

mechanisms of macrocytic anemia

A
  • abnorm in DNA metabolism (b12 or folate def)
  • shift to immature cells
  • bone marrow disorders- MDS
  • hypothyroidism
  • alcoholism
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3
Q

how does alcoholism cause macrocytic anemia

A
  • unknown mechanism
  • acetaldehyde has direct effect on RBCs
  • d/t regular ingestion of 80 g of alcohol daily
  • resolution after 2-4 mo
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4
Q

types of macrocytic anemias

A
  • reticulocytosis
  • alcoholism
  • liver disease
  • hypothyroidism
  • med effect
  • aplastic anemia
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5
Q

types of megaloblastic anemia

A
  • B12 def

- folic acid def

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6
Q

meds that cause macrocytic anemias

A
  • combo antiretroviral therapy for HIV
  • hydroxyurea for sickle cell disease
  • mtx- inhibits dihydrofolate reductase
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7
Q

aplastic anemia

A
  • considered a macrocytic anemia
  • more common in Asia
  • biphasic age distribution: 10-25 vs > 60
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8
Q

causes of aplastic anemia

A
  • acquired causes
  • autoimmune
  • congenital causes
  • fanconi anemia
  • dyskeratosis congential
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9
Q

acquired causes of aplastic anemia

A
  • radiation and chemo, toxins
  • viral infx
  • drugs
  • immune disorders
  • pregnancy
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10
Q

clinical presentation of aplastic anemia

A
  • weakness, fatigue
  • cardiopulm compromise
  • progressive anemia
  • mucosal/ skin bleeding, petechiae, menorrhea in women
  • recurrent infx
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11
Q

what is a common cause of death in aplastic anemia

A
  • invasive fungal infections
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12
Q

PE findings for aplastic anemia

A
  • generally not helpful
  • pallor or petechiae common
  • purpura
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13
Q

lab study findings in aplastic anemia

A
  • pancytopenia, severe anemia
  • normocytic or macrocytic
  • decreased or absent polychromic RBCs
  • reduced cell components, morphologically normal
  • abnormal cells NOT present
  • retic count decreased
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14
Q

diagnostic criteria for aplastic anemia

A
  • bone marrow cellularity < 30%
  • absence of severe pancytopenia
  • depression of 2-3 blood elements below normal
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15
Q

severe aplastic anemia criteria

A
  • bone marrow bx shows < 25%
  • OR
  • bone marrow bx showing< 50% with the following:
  • < 30% of cells are hematopoietic
  • absolute retic count < 40,000
  • absolute neutrophil count < 500
  • platelet count < 20,000
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16
Q

very severe aplastic anemia

A
  • criteria for severe met

- ANC < 200

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17
Q

essentials for dx of aplastic anemia

A
  • pancytopenia
  • no abnormal hematopoietic cells in circulation or in bone marrow
  • hypocellular bone marrow
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18
Q

treatment for mild-mod aplastic anemia

A
  • supportive care, treat underlying cause
  • EPO GF likely wont work
  • myeloid GF
  • transfusions
  • abx or antifungals for infx
  • monitor closely
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19
Q

treatment for severe aplastic anemia

A
  • allogenic HSCT tx of choice in kids < 20, preferred in adults 20-50
  • immunosuppressive if adults > 50 without HLA match, consider with severe comorbidities
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20
Q

prognosis of aplastic anemia

A
  • if untreated 70% 1 year mortality
  • rapidly fatal if severe and untreated
  • most die from fungal infections
  • good survival if HSCT, immunosupressives, improved supportive care
  • 1/3 of pts will relapse
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21
Q

fanconi anemia

A
  • most common cause of congenital inherited aplastic anemia
  • autosomal recessive, dx very young d/t severe congenital abnorm
  • progressive bone marrow failure
22
Q

what is a complication of fanconi anemia

A
  • increased malignancy like AML or ALL
23
Q

treatment for fanconi anemia

A
  • supportive modalities
  • androgens
  • hematopoietic GF for transient improvement
  • many become refractory or dev intolerable side effects
  • allogenic HSCT is only option to restore function
24
Q

when would you consider a B12 or folate deficiency based on H&P

A
  • unexplained neuro si/sx
  • older adults
  • alcoholics
  • patients with malnutrition
  • bariatric surgery pts
25
Q

b12 absorption

A
  • comes from animal products: meat, fish, dairy
  • requires intrinsic factor to be absorbed
  • B12 + intrinsic factor complex absorbed in terminal ileum
26
Q

how long is B12 sotred for

A
  • 3 years
27
Q

what are the functions of B12

A
  • nucleic acid metabolism
  • myelin synthesis
  • critical for DNA synthesis and regulation
28
Q

causes of B12 deficiency

A
  • dietary def is rare
  • inadequate intrinsic factor
  • pancreatic insuff
  • ileal disease
  • competition for B12 in gut
  • meds that block absorption: PPIs, metformin
  • transcobalamin II def- rare
29
Q

si/sx of B12 def

A
  • based on severity of def
  • glossitis
  • vague GI disturbances
  • neurologic sx*
30
Q

neuro sx assoc with B12 def

A
  • peripheral nerves affected first- distal/ peripheral paresthesias
  • difficulty with balance and proprioception
  • altered cerebral function
31
Q

PE findings for B12 def

A
  • pale
  • mildly icteric or sallow
  • atrophic glossitis
  • decreased vibration
  • decreased proprioception
  • memory disturbances
32
Q

lab findings for B12 def

A
  • macrocytic, MCV 110-140
  • HCT as low as 10-15%
  • pancytopenia if severe
  • low retic count
  • low serum b12
  • elevated MMA*
  • elevated total homocystein*
  • elevated LHD and indirect bili
  • consider TSH and liver fn
33
Q

essentials of B12 def

A
  • macrocytic anemia
  • megaloblastic anemia
  • low serum B12
34
Q

treatment of B12 def

A
  • parenteral replacement if absorption issues: SC or IM
  • sublingual or PO replacement indef
  • concurrent folic acid tx: 1 mg PO 1-4 mo
  • transfusion rarely needed
35
Q

expected response to B12 def tx

A
  • immediate improval
  • hematologic picture normalizes in 2 mo
  • hypoK possible in first few days
  • reticulocytosis days 5-7
  • hypersegmented neutrophils disappear after 10-14 d
  • neuro sx may persist if present for > 6 mo before tx
36
Q

monitoring tx for B12 def

A
  • CBC: 1-2 weeks, 2 mo, periodic

- B12 levels: indefinite monitoring

37
Q

what is pernicious anemia

A
  • autoimmune disease
  • Ab destroy parietal cells -> atrophic gastritis, bind to/ neutralize intrinsic factor
  • higher risk for GI/ gastric cancers
  • must treat B12 def
38
Q

diagnosis of pernicious anemia

A
  • schilling test*
  • measure gastric acid secretion
  • Ab to intrinsic factor
  • anti-parietal cell Ab
  • serum gastrin elevated
  • serum pepsinogen low
  • ratio to pepsinogen I: pepsinogen II low
39
Q

where is folic acid found

A
  • fruits
  • leafy greens
  • folate= found in nature
  • folic acid= synthetic version
40
Q

daily requirements of folic acid

A
  • healthy pts: 50-100 mcg/d

- pregnant/ lactating pts: 600-800 mcg/d

41
Q

how long is folic acid stored in the body

A
  • 2-3 moths
42
Q

where is folic acid absorbed

A
  • through entire GIT

- duodenum or jejunum

43
Q

function of folic acid

A
  • common pathway with B12
  • nucleic acid metabolism
  • critical in DNA synthesis- synth in hematopoietic cells
44
Q

causes of folic acid def

A
  • inadequate daily intake*- most common
  • reduced absorption- rare
  • increased requirement i.e. pregnancy
  • excessive loss
  • meds
  • alcohol abuse- lower folic acid stores
45
Q

medications that can cause folic acid def

A
  • mtx
  • trimethoprim
  • ethanol
  • phenytoin
46
Q

si/sx of folic acid def

A
  • based on severity of anemia
  • glossitis
  • vague GI disturbances
  • NO neuro sx
47
Q

PE findings for folic acid def

A
  • depends on severity
  • pale
  • mildly icteric or sallow
  • atrophic glossitis
  • neuro exam normal*
48
Q

lab findings for folic acid def

A
  • macrocytic anemia- MCV 110-140
  • pancytopenia if severe
  • low retic count
  • normal B12
  • RBC folic acid level low
  • elevated homocysteine*
  • normal MMA*
  • elevated LDH and indirect bili
  • consider TSH and liver fn
49
Q

essentials of folic acid def dx

A
  • macrocytic anemia
  • megaloblastic blood smear
  • reduced folic acid levels in RBCs or serum
  • normal B12 levels
50
Q

treatment of folic acid def

A
  • folic acid PO daily for 1-4 mo or until hematologic recovery
  • continue tx if underlying cause cant be fixed
  • ensure no B12 def
51
Q

expected response to tx of folic acid def

A
  • rapid improvement within 5-7 d
  • reticulocytosis in 5-7 d
  • normalization of hematologic abnormalities within 2 mo

clin med IV (23 decks)

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