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heme/onc > sickle cell anemia > Flashcards

sickle cell anemia Flashcards

1
Q

sickle cell disease

  1. inheritance
  2. caused
  3. aa substitution
A
  1. A- co-dominant
  2. caused by a single base pair substitution in the Beta-globin gene
  3. glutamic acid to valine substitution
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2
Q

variant hemoglobin, meaning the
mutation imparts a biochemical change in
the hemoglobin molecule.

A

HbS

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3
Q

heterozygous inheritance or sickle trait

A

Hb AS

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4
Q

homozygous inheritance; severe disease

A

Hb SS

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5
Q

most benign of the sickle diseases

A

sickle cell trait

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6
Q

sickle cell trait:

  1. HbA:HbS ratio is
  2. trait is for
  3. risks
  4. primary clinical impact
  5. common in
A
  1. 60:40
  2. protects cells from assuming the sickle shape
  3. no anemia but risk of splenic infarction at high altitude and death with extreme dehydration/hyperthermia
  4. primary clinical impact is around child-bearing
  5. common in African-americand and less in hispanic americans
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7
Q

sickle cell disease includes

A
  1. Hb SS
  2. Hb Sc
  3. sickle thalassemia
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8
Q

disease modifiers for sickle cell disease

A
  1. tissue oxygenation status
  2. pH
  3. HbF levels
  4. co-inheritance of other hb gene abnormalities
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9
Q

Heterozygous inheritance of hemoglobin S offers some protection against

A

malaria

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10
Q

what leads to polymerization of HbS

A

RBC deoxygenation

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11
Q

HbS polymers have increased or decreased solubility

A

decreased

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12
Q

what can increase HbS

A

cellular dehydration

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13
Q

what happens when RBC become sickle

A

sickle RBC adhere to the vascular endothelium leading to an activation of coagulation and cytokines cascades leading to increased blood viscosity, entraptment of RBC and leading to vaso-occlusion and pain

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14
Q

Hemoglobin S polymers are unstable leading to _________ (both intra- and extra-vascular).

A

red cell hemolysis

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15
Q

due to the sickle survival shortened life to 10-16 days what happens to the bone marrow?

A

marrow erythropoiesis cannot fully compensate in severe hemolysis leading to anemia.

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16
Q

sickle disease the Hb is -_______ and the WBC/platelets are _____

A

sickle disease the Hb is decreased and the WBC/platelets are normal/elevated

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17
Q

MCV in HbSS

A

normal to low-normal

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18
Q

MCV in sickle thalassemia

A

low

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19
Q

MCV in HbSC

A

low

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20
Q

_____ HbS is insoluble in presence of a concentrated phosphate buffer solution and forms a turbid suspension

A

Deoxygenated

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21
Q

Sickle solubility test is positive in all sickle conditions but is unable to distinguish between the various genotypes (thus used as a screening test)

A

yep

22
Q

Hb electrophoresis on cellulose acetate

  1. HbS
  2. HbC
A
  1. HbS migrates more slowly than nl hb and fetal hb but migrates in smae position as Hb variants, HbD and HbG
  2. HbC migrates more slowly and in the same position as HbA2 and HbE
23
Q

citrates Agar (pH)

  1. S separated from
  2. C separated from
A
  1. D and G

2. A2 and E

24
Q

HbS by HPLC

A

has a distinct retention time

25
Q

sickle cell complications

A

multi organ disease

** pregnancy- perilous high morbidity and mortality

26
Q

erythroid aplasia, often due to parvovirus B19 infection

A

aplastic crisis

27
Q

pooling of erythrocytes in the

spleen with acute splenomegaly and shock-like state

A

sequestration crisis

28
Q

marked red cell hemolysis

A

hemolytic crisis

29
Q

acute pain exacerbations

obstruction of microcirculation with painful tissue hypoxia and microinfarction primarily of bones

A

Acute pain (vasoocclusive) crisis:

30
Q

chronic sickle cell complications (6)

A
  1. chronic hemolytic anemia
  2. pain syndrome
  3. skin- leg ulcers
  4. endocrinopathies- Growth retard
  5. Bone disease- acute dactylitis
  6. ocular
31
Q

often the first symptom of SCD in babies

A

acute dactylitis

Presents between 6-18 months as HbF levels decrease

Uncommon once hematopoiesis shifts to axial skeleton (≈ age 6)

32
Q

Most common lung complication in sickle disease and Most frequent cause of death in adults

A

acute chest syndrome

33
Q

Acute chest syndrome

  1. onset
  2. defined by
  3. repeat episodes lead to
A
  1. Onset insidious or rapid and fulminant evolving out of
    a pain crisis
  2. defined by new:
    - pulmonary infiltrate
    - pleuritic chest pain -
    - fever >38.5
    - dyspnea, tachypnea, wheezing, cough
  3. repeat episodes lead to pulmonary HTN and right sided heart failure (cor pulmonale)
34
Q

obliterative vasculopathy, with severe intimal hyperplasia,

fibrosis, and thrombosis

A

pulmonary HTN

35
Q

Joint space narrowing, erosion of acetabular plate –>

chronic pain, can require joint replacement

A

avascular necrosis

36
Q

Chronic hemolysis predisposes to leg ulcerations.

Very challenging to treat: hyperbaric oxygen, skin grafting

A

yep

37
Q

Free Hb is a potent inhibitor of all_____ → EC dysfunction & NO resistance

A

NO bioactivity

38
Q

Proliferative retinopathy similar to diabetic eye disease

Vitreous hemorrhage can lead to retinal detachment and blindness

A

sickle retinopathy

39
Q

Narrowing or occlusion of medium and large

cerebral arteries

A

CNS Vasculopathy & Stroke in SCD

40
Q

A leading cause of death in

children and adults with SCD

A

stroke

41
Q

which sickle type has the highest risk in developing stroke

A

HbSS

42
Q

Pathogenesis of stroke (2)

A
  1. ischemic infarcts

2. hemorrhagic stroke

43
Q

progressive vasculopathy arising from neo-vascularization to establish collateral flow because of large vessel occlusion (high incidence in Asians; “puff of smoke”)

A

moyamoya

44
Q

in adults over age 29; related

to the formation of moyamoya* vessels in the brain

A

hemorrhagic stroke SCD

45
Q

in children aged 2 - 9 years with

second peak in adults over 29 years

A

ischemic infarct SCD

46
Q

disease modifying therapy for sickle disease

A

hydroxyurea

47
Q

hydroxyurea mechanism

A

increases HbF production

48
Q

future managment of sickle disease

A
  1. bone marrow transplantation

2. L-glutamine to reduce intracellular oxidant stress and thus reducing pain crises

49
Q

treatment for sickle cell

A

treat some of the complications such as pain crisis, acute chest syndrome, ischemic stroke risk, intracranial hemorrhage

50
Q

red cell transfusion in SCD leads to

A

iron overload

51
Q

preventive car and health maintenance (3)

A
  1. folic acid- chronic anemia
  2. penicillin
  3. health maintenance

heme/onc (30 decks)

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