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All the things continued > 5.5 Normocytic anemias with extravascular Hemolysis > Flashcards

5.5 Normocytic anemias with extravascular Hemolysis Flashcards

1
Q

What, generally, is hereditary spherocytosis?

A

Mutation in the cytoskeletal components of RBCs, causing them to bulge into spheres d/t loss of membrane blebs

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2
Q

What are the cytoskeletal tethering proteins that are defective in hereditary spherocytosis? (3)

A
  • Spectrin
  • Ankyrin
  • Band 3.1
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3
Q

What is the RDW with hereditary spherocytosis? Why?

A

Large, since there is a large variation between new and old RBCs

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4
Q

What causes the anemia with hereditary spherocytosis?

A

RBCs are consumed by the macrophages in the spleen

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5
Q

What happens to the MCHC with hereditary spherocytosis? Why?

A

Increases–Same amount of Hb in a smaller RBC

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6
Q

What are the clinical features of hereditary spherocytosis?

A
  • Splenomegaly
  • Jaundice with unconjugated bili
  • Increased risk for bilirubin gallstones
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7
Q

There is an increased risk of aplastic crisis in patients with hereditary spherocytosis with what infectious disease? Why?

A

Parvovirus B19–infects the erythroid precursors

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8
Q

What causes the splenomegaly with hereditary spherocytosis?

A

Work hypertrophy

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9
Q

What is the classic test to diagnose hereditary spherocytosis? What is the basis for this?

A

Osmotic fragility test–Increased fragility in a hypotonic solution, since the loss of membrane that occurs with hereditary spherocytosis leaves no room for excess water to accumulate.

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10
Q

What is the treatment for hereditary spherocytosis?

A

Splenectomy

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11
Q

What are the classic peripheral blood smear findings with a splenectomy? What causes this?

A

Howell-Jolly bodies–lack of removal of DNA from RBCs due to a loss of splenic macrophages

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12
Q

What is the problem that occurs in sickle cell anemia? Inheritance pattern?

A

AR mutation in the beta globin chain, where a glutamic acid is replaced with a valine

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13
Q

What causes the RBCs to sickle with sickle cell anemia?

A

Hydrophobic valine patch causes RBCs to stick together to hide hydrophobic patch away from water in the serum

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14
Q

What is the supposed benefit of sickle cell anemia?

A

Protection against falciparum malaria

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15
Q

When does sickle cell disease result, as opposed to sickle cell trait?

A

Trait = one mutated beta globin gene

Disease = both beta globin genes are mutated

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16
Q

What are the components of HbS?

A

Alpha-2 beta (S) 2

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17
Q

HbS polymerize with under what conditions? (3)

A
  • Deoxygenation
  • Dehydration
  • Acidosis
18
Q

What is the role of HbF in sickle cell disease?

A
  • Protective factor in the first few months of life

- Hydroxyurea increases levels of HbF

19
Q

What is the role of hydroxyurea in the treatment of sickle cell anemia?

A

Increases levels of HbF

20
Q

What is the problem that occurs with constant cycling of sickling seen with HbS?

A

Results in damage to the RBC membrane, leading to decreased flexibility

21
Q

What are the clinical characteristics of sickle cell anemia?

A
  • Anemia
  • Jaundice with unconjugated bili
  • Increased risk for bili gallstones
22
Q

What happens to haptoglobin levels with sickle cell disease?

A

Decreased due to intravascular hemolysis

23
Q

What are the PBS findings with sickle cell disease? Why?

A
  • Target cells

- Dehydration of cells causes blebbing of RBCs with Hb accumulation in the blebs

24
Q

What are findings of the erythroid hyperplasia seen with sickle cell disease?

A

Chipmunk facies

  • Crewcut appearance of the skull on x-ray
  • HSM
25
Q

What are the complications that arise from the irreversible sickling that is seen with sickle cell disease?

A

Vasoocclusion and infarction of tissues

26
Q

What is the common presenting sign of sickle cell disease in infants? Why?

A

Dactylitis–Vaso-occlusive infarct of bones with sickling

27
Q

What causes the autosplenectomy seen with sickle cell disease?

A

Infarction of the spleen from vasoocclusion by sickled RBCs

28
Q

What bacteria is the classic cause of osteomyelitis with sickle cell disease?

A

Salmonella paratyphi

29
Q

What are the characteristics PBS findings with splenectomy?

A

Howell-Jolly bodies

30
Q

What are the SHINE SKiS bacteria that patients with sickle cell disease are susceptible to?

A
  • Strep pneumo
  • HiB
  • Neisseria meningitidis
  • E. Coli
  • Salmonella
  • Klebsiella
  • GBS
31
Q

What is the most common cause of osteomyelitis overall?

A

Staph aureus

32
Q

What is the acute chest syndrome seen with sickle cell disease? What are the s/sx of this?

A
  • Vaso-occlusion in the pulmonary microcirculation

- Chest pain, SOB

33
Q

What is the most common cause of death with sickle cell disease?

A

Acute chest syndrome

34
Q

What usually precipitates episodes of acute chest syndrome in patients with sickle cell disease? Why?

A
  • Pneumonia
  • Causes vasodilation, which increases transit time for RBCs, and increases the chances that sickled RBCs will sickle and occlude
35
Q

What are the renal sequelae of sickle cell disease? How does this present?

A
  • Renal papillary necrosis

- Gross hematuria and proteinuria

36
Q

How much HbS is needed to cause sickling? Why is this relevant?

A

More than 50%

-Explains why sickle cell trait does not lead to the same issues as sickle cell disease

37
Q

Generally, RBCs in sickle cell trait do not sickle, and thus do not cause problems. There is one exception to this however. What is this? Why?

A

Renal medulla has extreme hypoxia and hypertonicity, causing microinfarctions, leading to progressive kidney damage

38
Q

What are the clinical findings of renal medulla damage with sickle cell trait?

A
  • Microscopic hematuria

- Decreased ability to concentrate urine

39
Q

What is the chemical that can cause cells to sickle if HbS is present at all?

A

Metabisulfite

40
Q

What happens to HbA with sickle cell disease?

A

Absent

41
Q

What is the amino acid change that occurs with hemoglobin C? What is the inheritance pattern of this?

A
  • AR mutation in beta chain

- Glutamic acid to lysine (“lys-ccc-ene”)

42
Q

What is the classic PBS finding of HbC?

A

Hb C crystals

All the things continued (28 decks)

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