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Hematology > Hemoglobinopathies > Flashcards

Hemoglobinopathies Flashcards

1
Q

Hemoglobinopathies

A

Qualitative or Quantitative Abnormalities in the syntesis of hemoglobin

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2
Q

Thalassemia

A

Quantitative abnormalities resulting in decrease in production of globin chains in hemoglobin

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3
Q

Intracorpuscular defects

A

Hemoglobinopothies
- Defects in RBC membrane
- Defects in Metabolic Enzymes
- Paroxysmal Nocturnal Hemoglobinuria

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4
Q

Abnormal Hemoglobins - genetics

A

Most abnormalities arise from a single amino acid substitution and express co-dominance

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5
Q

Homozygous is almost always affects more

A

Disease

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6
Q

Heterozygous, may have slight, if any, clinical symptoms

A

Trait

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7
Q

Hemoglobin S structure

A

2 Alpha chains
2 Beta(6) Glu -> Val

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8
Q

Sickle cell

A

group of genetic disorders caracterized by the producion ot abnormal Hemoglobin S

most common severe hemoglobinopathy worldwide

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9
Q

Sickle Cell
Beta chain 6th position:

A

Valine substitutes glutamic acid

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10
Q

Homozygous inheritance = SS

A

A2 B2 ^6Glu-Val

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11
Q

Heterozygous inheritance = SA

A

A2 B1 B1 ^ 6Glu-Val

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12
Q

Hemoglobin S has no problem when

A

oxygenated

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13
Q

sickle cell anemia in the body

A
  • Low O2 tension, pH, or hydration,
  • Hgb S polymerizes
  • Polymers form long, thin fibers causing RBC to become inflexible and rigid
  • RBC sickles
  • RBC sickling (RBC sickling is reversible up to a point)
  • Repeated sickling damages RBC membrane permeability
  • Hgb S polymers cause abnormal cation homeostasis leading to sickle cell dehydration
  • cells become dehydrated, dense, irreversibly sickled cells
  • leads to hemolytic anemia and cases of vaso-occlusion
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14
Q

Vasooclusion further lowers the pH and O2 tension, leads to..

A
  1. Increased sickle cells
  2. results in tissue damage, painful crisis and infarction of organs
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15
Q

Sickle cell anemia is a…

A

normocytic, normochromic hemolytic anemia

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16
Q

vaso-occlusions

A

ischemic tissue injury

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17
Q

organs at greatest risk (Sickle cell anemia)

A

Spleen, kidney, and BM

  • blood flow is slowed through sinuses
  • O2 tension and pH are decreased
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18
Q

3 sickle cell anemia crisis

A
  1. Aplastic
  2. Vaso-occlusive
  3. Hemolytic
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19
Q

Sickle cell anemia - Aplastic crisis

A
  • temporary suppression of erythopoiesis - often initated from infections (esp. parvoviruses)
  • BM becomes overworked and decrease in production
    1. Since RBC is already shortened (10-20 days)
    2. any decrease in RBC production results in anemia
  • Reticulocyte count decreased
  • Often spontaneous recovery within 5-10 days (usually self-limiting)

Treatment option: Transfusion

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20
Q

Aplastic crisis

A

Decresed reticulocyte count

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21
Q

Sickle Cell Anemia - Hemolytic crisis

A

Acute exarbation of anemia
- caused by acute splenic sequestration (sickled cells pooling in spleen)

Spleen is enlarged and can develop mutliple infarctions/fibrosis
- leads to “autosplenectomy” aka functional asplenia
1. spleen becomes small, fibrotic and nonfunctional

Resticulocyte Count INCREASED - BM is responding

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22
Q

SS - hemolytic crisis symptoms

A
  • Sudden weakness
  • rapid pulse
  • faintness
  • pallor of the lips and mucous membranes
  • abdominal fullness
  • jaundice
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23
Q

SS - Vaso-occlusive crisis

A

“Hallmark of sickle cell anemia”

Occlusion of small blood vessels -> tissue damage and necrosis

Time span: 4-6 days but can persist for weeks

symptoms - PAIN

Worsened with infectiction, fever, acidosis, dehydration and exposure to extreme cold..
- children are prone to encapsulated organisms

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24
Q

Sickle cell anemia - Vaso-occlusive crisis treatment

A
  • adequate rehydration
  • pain relief
  • antibiotic therapy if infection is present
  • Severe cases –> exchange transfusion
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25
Q

Sickle cell anemia complications

A
  • Acute Chest syndrome
  • Cutaneous Manifestations
  • Dactylitis
  • Hand - foot syndrome
  • Infections
  • stroke
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26
Q

SS anemia - Acute Chest Syndrome

A
  • occlusion in the pulmonary microvasculature
  • 2nd most common cause of hospital admissions in SS patients

Characterized by fever, chest pain, hypxia, and pulmonary infiltrates

Often caused by an infectious agent in children
- higher incidence of acute chest syndrome, lower mortality rate

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27
Q

Dactylitis (SS)

A

Painful swelling of hands and feet

28
Q

Cutaneous Manifestations (SS)

A
  • development of ulcers and sores
  • often on lower leg/shin
29
Q

SC anemia - Hand-Foot syndrome

A

Microinfarcation in small bones of hands feet lead to unequal growth and bone deformities

  • Especially fingers and toes
30
Q

SC anemia - Infections

A

Prone to recurrent infections that can lead to sepsis

Hemoglobin S has selective advantage against malaria.
- parasitized sickle cells faster leading to preferential destruction of parasitized cells.

31
Q

Sickle cell Anemia - stroke

A

Neurologic complications caused by an ischemia or hemorrhagic lesion in a specific cerebral vessel

32
Q

Sickle cell anemia treatment

A

Stem cell/BM transplant considered curative, but only considered in children or teenagers with complications

33
Q

Hydroxyurea

A

increases Hgb F production

34
Q

Erythropoietin

A

Increases reticulocytes

35
Q

SS anemia treatment (SYMPTOMS)

A
  • Hydroxurea
  • Erythropoietin
  • Prophylactic antibiotics
  • Crisis management
    1. transfusion
    2. pain medication
    3. vasodilators and O2
  • prevention education - good diet, hydration and avoid crisis initiators
36
Q

Sickle cell anemia lab findings

A

CBC and Reticulocyte
- Low Hgb, HCT, RBC count
(chronic hemolytic anemia)

  • Reticulocyte count Increased
    (EXCEPT aplastic crisis)
  • Normal MCV
    (may be increased from reticulocytes
37
Q

ESR/SED rate is _ in Sickle cell anemia

A

decreased

38
Q

only sickle cell crisis with DECREASED reticulocyte count

A

Aplastic crisis

39
Q

Peripheral smear Sickle cell anemia

A

Normocytic/ normochromic RBCs
Non crisis
- Some polychromasia; target cells
- few oat cells (reversible sickled cells)

Crisis
- Sickled cells (drepanocytes) and oat cells
- increased Erythropoiesis
- nRBCs
- Howell-Jolly Bodies
- Target Cells
- Potentially Schistocytes/fragments

40
Q

Sickle cell anemia - bone marrow

A

Marked erythroid hyperplasia
- response from chronic hemolytic anemia

41
Q

Sickle cell screen - Solubility testing (qualitative)

A

RBCs are lysed and the Hgb is released in a solution containinf sodium hydrosulfite or dithionite reducing hemoglobin
- redcued Hgb A is soluble
- Reduced Hgb S is insoluble - Turbid/opaque suspension

Any Hgb S present will result in a positive test
- including sickle cell trait

Caution: there are other very rare abnormal Hgb that can also give a positive result. DIagnosis requires further testing.

42
Q

Reduced Hgb S is

A

insoluble - tubid/opaque suspension

43
Q

what test is used with sickle cell hemoglobin

A

Electrophoresis

44
Q

Sickle cell trait Hemoglobins Present

A
  • 60% Hgb A1
  • 40% Hgb S
  • Tiny Hgb A2
  • Tiny Hgb F
45
Q

Sickle cell anemia hemoglobins present

A
  • > 80% Hgb S
  • <20% Hgb F
  • Tiny Hgb A2 (not always)
46
Q

Sickle cell trait

A

Heterozygous (SA)
- inherit normal beta globin gene and sickle globin gene

Hemoglobins formed
- 60% Hemoglobin A1
- 40% Hemoglobin S
- Tiny amount of Hgb A2 and F

Requires much more severe low oxygen for sickling to occur

Usually asymptomatic
- since potential sickling exists, must be cautionary with low O2 or pH.

47
Q

Hemoglobin C chains

A

2 alpha chains
2 beta (6th, Glu-Lys)

48
Q

Hemoglobin C

A

Beta chain 6th position: glutamic acid substituted by lysine (+)
- same position as Hgb S but with a positively charged amino acid

49
Q

Hemoglobin C disease (Chains)

A

A2 B2 (6thGlu-Lys)

50
Q

Hemoglobin C trait - Chains

A

A2 B1 B1(6thGlu-Lys)

51
Q

Hemoglobin C Disease

A

Milder normocytic, normochromic anemia

Possible: Increased MCHC - RBCs denser from Hgb C

52
Q

Hemoglobin C disease - Clinical manifestations

A
  • Splenomegaly
  • abdominal comfort
53
Q

Hemoglobin C disease - Peripheral smear

A
  • normocytic, normochromic RBCs
  • Numerous target cells
  • Hemoglobin CC crystals
  • Moderate polychromasia
54
Q

Hemoglobin C disease - Hemoglobin electrophoresis

A
  • 95% Hgb C
  • <7% Hgb F
  • NO Hgb A1/A2
55
Q

Hemoglobin C trait

A

Peripheral smear
- possible target cells

Hemoglobin electrophoresis
- 60% Hgb A1
- 40% Hgb C

56
Q

Hemoglobin SC disease -chains

A

Beta chain spot 6
- Glutamic acid -> valine (S)
- Glutamic acid -> lysine (C)

A2 B1(6Glu-Val) B1(6Glu-Lys)

57
Q

what type of anemia is Hemoglobin SC disease

A

moderate normocytic, normochromic anemia

58
Q

peripheral smear of SC disease

A
  • target cells
  • folded cells
  • Hgb SC crystals
  • Slight polychromasia
59
Q

Hgb Electrophoresis SC disease

A

50% Hgb S
50% Hgb C

60
Q

Hemoglobin S - Beta Thalassemia

What type of anemia?

A

Microcytic, hypochromic anemia

61
Q

Hemoglobin S - Beta Thalassemia

Chains

A

A2 B1(6Glu-Val) B1(+ or 0)

62
Q

Hemoglobin S - Beta thalassemia

Peripheral smear

A
  • nRBCs
  • Target cells
  • polychromasia
  • sickle cells
63
Q

Beta 0

A

most severe

64
Q

Beta+

A

less severe

65
Q

Hemoglobin S - Beta Thalassemia

Additional lab findings

A
  • Increased reticulocyte count
  • increased RDW
  • Hgb electrophoresis -> Hgb S and HgbA2

Hematology (36 decks)

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