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Heme/Onc > RBC Disorders > Flashcards

RBC Disorders Flashcards

1
Q

What is the role of ferroportin?

A

Transports iron enterocytes –> blood

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2
Q

What is the role of transferrin?

A

Transports iron in blood –> liver & bone marrow macrophages

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3
Q

How are measures of serum ferritin & TIBC related?

A

Always opposite! Iron stores versus iron transferrin in blood

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4
Q

What is the most common of iron deficiency anemia in:

  • Infants
  • Children
  • Adults
  • Elderly
A
  • Breast feeding, prematurity
  • Poor diet
  • Peptic ulcer disease (males) or menorrhagia/pregnancy (females)
  • Colon polyps/carcinoma or hookworm
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5
Q

Why are individuals with a gastrectomy at risk for iron deficiency anemia?

A

Acid secreted by parietal cells in stomach aids in iron absorption by maintaining Fe2+ state

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6
Q

What are the four stages of iron deficiency anemia?

A
  1. Storage iron depleted
  2. Serum iron depleted
  3. Normocytic anemia: fewer cells but normal size
  4. Microcytic, hypochromic anemia
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7
Q

What are some clinical features of iron deficiency anemia?

A

Pica and koilonychia (spoon shaped nails)

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8
Q

What are some lab findings of iron deficiency anemia?

A
  1. Microcytic, hypochromic RBCs w/ increased RDW
  2. Decreased ferritin, increased TIBC, decreased saturation, decreased serum iron
  3. Increased free erythrocyte protoporphyrin
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9
Q

What is Plummer-Vinson syndrome?

A

Iron deficiency anemia with:

  • Esophageal web –> dysphagia
  • Atrophic glossitis –> beefy-red tongue
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10
Q

What is the most common type of anemia in hospitalized patients?

A

Anemia of chronic disease

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11
Q

How does hepcidin play a role in anemia of chronic disease?

A

Hepcidin sequesters iron storage by:

1) Limiting iron transfer from macrophages to erythroid precursors
2) Suppressing EPO production
* Body thinks its an infection and wants to prevent bacteria from getting iron!

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12
Q

What are the ringed sideroblasts in sideroblastic anemia?

A

Iron enters mitochondria to form heme; defect in protoporphyrin synthesis so no protoporphyrin; iron stays in mitochondria –> iron-laden mitochondria form a ring around nucleus = ringed sideroblasts

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13
Q

What are some causes of sideroblastic anemia?

A
  1. Congenital: commonly involves ALAS
  2. Alcoholism: mitochondrial poison
  3. Lead poisoning: denatures ferrochelatase and ALAD
  4. B6 Deficiency: B6 cofactor for rate limiting step; commonly side effect of isoniazid treatment for TB
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14
Q

Why is there a high serum iron concentration in sideroblastic anemia?

A

Iron overloaded state: excess iron in cells generates radicals –> cause cells to die –> BM macrophages eat up this iron & some released into blood

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15
Q

The alpha genes involved in alpha thalassemia are on what chromosome?

A

Four alpha genes on chromosome 16

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16
Q

How does alpha thalassemia minor present?

A

Two gene delations lead to mild anemia with increased RBC count
Cis deletion –> East Asians; worse, increased risk in offspring
Trans deletion –> Africans

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17
Q

Three alpha gene deletions lead to?

A

Formation of HbH = beta4 –> severe anemia

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18
Q

Four alpha gene deletions lead to?

A

Hydrops fetalis: lethal in utero

Formation of Hb Barts = gamma4 - damage RBCs

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19
Q

What is the inheritance pattern of thalassemias?

A

Autosomal recessive

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20
Q

Which populations are Beta thalassemias commonly seen in?

A

Individuals with African or Mediterranean descent

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21
Q

What chromosome are the beta genes for hemoglobin production on?

A

Two beta genes on Chromosome 11

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22
Q

What is beta thalassemia minor characterized by?

A

Asymptomatic with increased RBC
Microcytic, hypochromic RBCs and target cells on blood smear
Hb electrophoresis: increased HbA2

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23
Q

What is beta thalassemia major characterized by?

A
  1. Alpha tetramers aggregate and damage RBCs –> ineffective erythropoeisis; making defective RBCs that are eaten by spleen = extravascular hemolysis
  2. Massive erythyroid hyperplasia –> crewcut skull, facial bones, hepatosplenomegaly (hematopoiesis), risk of aplastic crisis with B19
  3. Chronic transfusions; may lead to secondary hemochromatosis
  4. Blood smear with microcytic, hypochromic RBCs with target cells and nucleated RBCs
  5. Hb electrophoresis with no HbA, increased HbA2 and HbF
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24
Q

When does beta thalassemia major usually present?

A

A few months after birth; before that, patients have HbF to compensate

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25
Q

Why do we see target cells in thalassemias? What else are they seen in?

A

Target cells involve loss of central pallor of RBCs and center is instead pink. Decreased Hb in cytoplasm forms membrane blebs where Hb goes to.
*Also seen in other hemoglobinopathies (sickle cell), iron deficiency anemia and liver disease

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26
Q

What are some features of macrocytic anemias?

A
  1. Megaloblastic anemia (big RBCs and other cells)
  2. Hypersegmented neutrophils (impaired division of granulocytes)
  3. Megaloblastic changes in rapidly-dividing epithelial cells (ex: intestinal)
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27
Q

What are some causes of macrocytic anemia besides folate and B12 deficiency?

A

Alcoholism, liver disease, drugs (5-FU, phenytoin)

*Do not see megaloblastic changes - nuclei are mature

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28
Q

What is the most common cause of folate deficiency?

A

Alcoholics! Poor diet

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29
Q

What are some clinical and lab findings of folate deficiency?

A
  1. Macrocytic RBCs & hypersegmented neutrophils
  2. Glossitis
  3. Decreased serum folate
  4. Increased serum homocysteine
  5. Normal metylmalonic acid
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30
Q

What is the most common cause of B12 deficiency?

A

Pernicious anemia: autoimmune destruction of parietal cells; seen in middle-older age & associated with other autoimmune diseases

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31
Q

What are some other causes of B12 deficiency?

A
  1. Pancreatitis
  2. Damage to terminal ileum
  3. Dietary deficiency (rare)
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32
Q

What are some clinical and lab findings of B12 deficiency?

A
  1. Macrocytic RBCs & hypersegmented neutrophils
  2. Glossitis
  3. Degeneration of spinal cord - irreversible
  4. Decreased serum B12
  5. Increased serum homocysteine
  6. Increased metylmalonic acid
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33
Q

How do you is reticulocyte count corrected for in anemia? How is this number analyzed?

A

RC X Hematocrit/45

  1. Corrected count > 3% –> good bone marrow compensation; peripheral RBC destruction causing anemia
  2. Corrected count < 3% –> poor bone marrow compensation; bone marrow underproduction causing anemia
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34
Q

What are some features of extravascular hemolysis?

A
  1. Anemia with splenomegaly (eating RBCs)
  2. Jaundice (unconjugated bilirubin)
  3. Increased risk for bilirubin gallstones
  4. Marrow hyperplasia (trying to make more RBCs)
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35
Q

How would you describe extravascular hemolysis?

A

RBC destruction by reticuloendothelial system (spleen, liver, lymph nodes)

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36
Q

How would you describe intravascular hemolysis?

A

Destruction of RBCs within vessels

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37
Q

What are some clinical and lab findings of intravascular hemolysis?

A
  1. Hemoglobinemia
  2. Hemoglobinuria
  3. Hemosiderinuria: from hemosiderin accumulations in tubular cells
  4. Decreased free serum haptoglobin
38
Q

What is the inheritance pattern of hereditary spherocytosis?

A

Autosomal dominant

39
Q

What is the defect in hereditary spherocytosis?

A

Defect of RBC cytoskeleton-membrane tethering proteins (spectrin, ankyrin, band 3.1)

40
Q

Why are spherocytes seen in hereditary spherocytosis?

A

No cytoskeleton to maintain shape –> loss of membrane –> round cells with loss of central pallor

41
Q

What is the extravascular hemolysis in hereditary spherocytosis?

A

Spherocytes unable to maneuver through splenic sinusoids –> eaten by spleen

42
Q

What are the clinical and laboratory findings of hereditary spherocytosis?

A
  1. Spherocytes with loss of central pallor
  2. Increased RDW and MCHC
  3. Extravascular signs
  4. Increased risk for aplastic crisis w/ Parvovirus B19
43
Q

How do you diagnose hereditary spherocytosis?

A

Osmotic fragility test; spherocyte bursts in hypotonic solution (water enters cell) because has no membrane

44
Q

How do you treat hereditary spherocytosis?

A

Splenectomy: anemia bye bye but spherocytes stay & may see Howell-Jolly bodies

45
Q

Sickle cell anemia involves which mutation?

A

Autosomal recessive mutation in Beta chain; glutamic acid –> valine

46
Q

How many abnormal genes are needed for someone to have sickle cell disease?

A

Two mutated beta genes –> >90% HbS

47
Q

What conditions cause HbS to sickle?

A

Deoxygenated states: acidosis, high altitude, dehydration, hypoxemia

48
Q

How does sickle cell involve extravascular hemolysis?

A

Cells sickle and de-sickle –> RBC membrane damage

Reticuloendothelial system eats up RBCs with damaged membranes

49
Q

How does sickle cell involve intravascular hemolysis?

A

RBCs with damaged membranes dehydrate –> hemolysis –> decreased haptoglobin and target cells

50
Q

What does irreversible sickling lead to, which in turn causes the major complications of sickle cell disease?

A

Vaso-occlusion

51
Q

What are 5 complications of vaso-occlusion in sickle cell?

A
  1. Dactylitis (common in infants)
  2. Autosplenectomy (increased risk of infection w/ encapsulated organisms; salmonella typhi osteomyelitis, HJ bodies)
  3. Acute chest syndrome (often following pneumonia - increases chances of deoxygenation)
  4. Pain crisis
  5. Renal papillary necrosis (hematuria, proteinuria)
52
Q

What is sickle cell trait characterized by? What place in the body might be susceptible to damage?

A

One normal, one mutated chain. < 50% HbS in RBCs so does not sickle except in RENAL MEDULLA
*Extreme hypoxia and hypertonicity of medulla can cause sickling

53
Q

What is the metabisulfite screening test used for?

A

Causes with any amount of HbS (sickle cell disease and trait) to sickle

54
Q

What is the inheritance pattern for Hemoglobin C? What is the mutation?

A

Autosomal recessive; glutamic acid –> lysine

55
Q

How do individuals with Hemoglobin C present?

A

Mild anemia due to extravascular hemolysis; hemoglobin C crystals in RBCs on smear

56
Q

How does someone get paroxysmal nocturnal hemoglobinuria (PNH)?

A

ACQUIRED defect in myeloid stem cells resulting in absent GPI

57
Q

What are the roles of decay accelerating factor (DAF) and Membrane Inhibitor of Reactive Lysis (MIRL)?

A

On surface of RBCs and protect against complement-mediated damage by inhibiting C3 convertase

58
Q

Why is paroxysmal nocturnal hemoglobinuria episodic and at night?

A

Shallow breathing during night leads to a mild respiratory acidosis which activates complement

59
Q

Which types of cells are lysed in PNH?

A

RBCs, WBCs, platelets

60
Q

Which test is used to screen for PNH?

A

Sucrose test.

61
Q

Which test is used to diagnose PNH?

A

Acidified serum test or flow cytometry (detects lack of CD55/CD59)

62
Q

What is the main cause of death in individuals with PNH?

A

Thrombosis of hepatic, portal or cerebral veins; destroyed platelets release cytoplasmic contents into circulation –> thrombosis

63
Q

Name 2 complications of PNH.

A
  1. Iron deficiency anemia (losing Hb)

2. AML (10% of patients; more susceptible to a 2nd mutation)

64
Q

What is the inheritance pattern for G6PD deficiency?

A

X linked recessive

65
Q

What are the two major variants of G6PD deficiency? Which is more severe?

A
  1. African Variant: mildly reduced half life of G6PD –> no G6PD in older RBCs –> only older RBCs lysed
  2. Mediterranean Variant: markedly reduced half life of G6PD –> older & younger RBCs lysed
66
Q

What are Heinz bodies?

A

Precipitated Hb

67
Q

Under what conditions will you see symptoms of G6PD deficiency?

A

Oxidative stress: infections, drugs (primaquine, sulfa, dapsone), fava beans

68
Q

How do extravascular and intravascular hemolysis occur in G6PD deficiency? Which is predominant?

A

Splenic macrophages bite Heinz bodies –> bite cells –> some extravascular hemolysis can occur where macrophages eat entire cell but mostly intravascular hemolysis

69
Q

What do patients with G6PD deficiency present with?

A

Hemoglobinuria and back pain (Hb is nephrotoxic) hours after oxidative stress

70
Q

What is used to screen for G6PD deficiency?

A

Heinz preparation

71
Q

What is used to diagnose G6PD deficiency? When is this test performed?

A

Enzyme studies; performed weeks after hemolytic episode resolves

72
Q

What are the two types of immune hemolytic anemia?

A

IgG mediated (extravascular hemolysis) and IgM mediated (intravascular hemolysis)

73
Q

Which disease does the blood smear of IgG-mediated immune hemolytic disease resemble?

A

Hereditary spherocytosis! You also see spherocytes with warm agglutinins

74
Q

How do spherocytes form in IgG-mediated immune hemolytic disease?

A

IgG binds RBCs in warm temperature of central body –> splenic macrophages consume antibody-coated RBC –> spherocytes –> spherocytes eventually eaten by splenic macrophages

75
Q

What is IgG-mediated immune hemolytic anemia associated with?

A

SLE (MCC), CLL, drugs (penicillin & cephalosporins)

76
Q

How can drugs induce IgG-mediated immune hemolytic anemia?

A
  1. Drug may attach to RBC membrane and antibody binds to complex (penicillin)
  2. Drug may induce production of autoantibodies that bind to self antigens on RBCs (methyldopa)
77
Q

How do you treat IgG-mediated immune hemolytic anemia?

A

Treat underlying cause, IVIG, splenectomy (two birds one stone)

78
Q

What process causes hemolysis in IgM-mediated immune hemolytic anemia?

A

IgM binds RBCs and fixes complement in cold temperature of extremities

79
Q

What is IgM Mediated immune hemolytic anemia associated with?

A

Mycoplasma pneumoniae and infectious mononucleosis

80
Q

Which test is used to diagnose immune hemolytic anemia? Which is more important?

A

Coombs test - direct and indirect

Direct most important test for IHA

81
Q

What is malaria transmitted by?

A

Anopholes mosquito

82
Q

What organs/cells does Plasmodium infect?

A

RBCs and liver

83
Q

What type of hemolysis occurs in malaria? What is the cause of the hemolysis?

A

Intravascular hemolysis and cyclical fever occur as a part of the Plasmodium life cycle

84
Q

Is there any extravascular hemolysis in malaria?

A

Yes! Spleen consumes some infected RBCs –> mild extravascular hemolysis with splenomegaly

85
Q

What are some causes of anemia due to underproduction?

A

Renal failure (decreased EPO), damage to bone marrow precursor cells

86
Q

How does Parvovirus B19 cause red cell aplasia?

A

Infects RBC precursors and halts erythropoiesis –> significant anemia in people dependent on RBCs!

87
Q

How do you treat Parvovirus B19?

A

Supportive treatment; self-limited infection

88
Q

What is aplastic anemia? What is it caused by?

A

Damage to HSCs resulting in pancytopenia & low reticulocyte count; causes: drugs/chemicals, viral infections, autoimmune damage

89
Q

What does the biopsy of someone with aplastic anemia show?

A

Empty, fatty marrow

90
Q

How do you treat aplastic anemia?

A

Treat underlying cause; can use immunosuppression and may need bone marrow transplant

91
Q

What is a myelopthisic process?

A

Pathologic process (metastatic cancer) that replaces bone marrow –> impairs hematopoiesis –> pancytopenia

Heme/Onc (3 decks)

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