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Hemoglobinopathies Flashcards

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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
Sickle cell anemia complications
- Acute Chest syndrome - Cutaneous Manifestations - Dactylitis - Hand - foot syndrome - Infections - stroke
26
SS anemia - Acute Chest Syndrome
- 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
27
Dactylitis (SS)
Painful swelling of hands and feet
28
Cutaneous Manifestations (SS)
- development of ulcers and sores - often on lower leg/shin
29
SC anemia - Hand-Foot syndrome
Microinfarcation in small bones of hands feet lead to unequal growth and bone deformities - Especially fingers and toes
30
SC anemia - Infections
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
Sickle cell Anemia - stroke
Neurologic complications caused by an ischemia or hemorrhagic lesion in a specific cerebral vessel
32
Sickle cell anemia treatment
Stem cell/BM transplant considered curative, but only considered in children or teenagers with complications
33
Hydroxyurea
increases Hgb F production
34
Erythropoietin
Increases reticulocytes
35
SS anemia treatment (SYMPTOMS)
- 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
Sickle cell anemia lab findings
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
ESR/SED rate is _ in Sickle cell anemia
decreased
38
only sickle cell crisis with DECREASED reticulocyte count
Aplastic crisis
39
Peripheral smear Sickle cell anemia
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
Sickle cell anemia - bone marrow
Marked erythroid hyperplasia - response from chronic hemolytic anemia
41
Sickle cell screen - Solubility testing (qualitative)
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
Reduced Hgb S is
insoluble - tubid/opaque suspension
43
what test is used with sickle cell hemoglobin
Electrophoresis
44
Sickle cell **trait** Hemoglobins Present
- 60% Hgb A1 - 40% Hgb S - Tiny Hgb A2 - Tiny Hgb F
45
**Sickle cell anemia** hemoglobins present
- >80% Hgb S - <20% Hgb F - Tiny Hgb A2 (not always)
46
Sickle cell trait
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
Hemoglobin C chains
2 alpha chains 2 beta (6th, Glu-Lys)
48
Hemoglobin C
Beta chain 6th position: glutamic acid substituted by lysine (+) - same position as Hgb S but with a positively charged amino acid
49
Hemoglobin C disease (Chains)
A2 B2 (6thGlu-Lys)
50
Hemoglobin C trait - Chains
A2 B1 B1(6thGlu-Lys)
51
Hemoglobin C Disease
Milder normocytic, normochromic anemia Possible: Increased MCHC - RBCs denser from Hgb C
52
Hemoglobin C disease - Clinical manifestations
- Splenomegaly - abdominal comfort
53
Hemoglobin C disease - Peripheral smear
- normocytic, normochromic RBCs - Numerous target cells - Hemoglobin CC crystals - Moderate polychromasia
54
Hemoglobin C disease - Hemoglobin electrophoresis
- 95% Hgb C - <7% Hgb F - NO Hgb A1/A2
55
Hemoglobin C trait
Peripheral smear - possible target cells Hemoglobin electrophoresis - 60% Hgb A1 - 40% Hgb C
56
Hemoglobin SC disease -chains
Beta chain spot 6 - Glutamic acid -> valine (S) - Glutamic acid -> lysine (C) A2 B1(6Glu-Val) B1(6Glu-Lys)
57
what type of anemia is Hemoglobin SC disease
moderate normocytic, normochromic anemia
58
peripheral smear of SC disease
- target cells - folded cells - Hgb SC crystals - Slight polychromasia
59
Hgb Electrophoresis SC disease
50% Hgb S 50% Hgb C
60
Hemoglobin S - Beta Thalassemia What type of anemia?
Microcytic, hypochromic anemia
61
Hemoglobin S - Beta Thalassemia Chains
A2 B1(6Glu-Val) B1(+ or 0)
62
Hemoglobin S - Beta thalassemia Peripheral smear
- nRBCs - Target cells - polychromasia - sickle cells
63
Beta 0
most severe
64
Beta+
less severe
65
Hemoglobin S - Beta Thalassemia Additional lab findings
- Increased reticulocyte count - increased RDW - Hgb electrophoresis -> Hgb S and HgbA2

Hematology (36 decks)

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