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My Pathoma Unit 2 > Chapter 5 Red Blood Cell Disorders > Flashcards

Chapter 5 Red Blood Cell Disorders Flashcards

1
Q

What are the 4 main microcytic anemias?

A

Iron deficiency, chronic disease, sideroblastic, thalassemia

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2
Q

Where is iron absorbed and what is the transporter?

A

In the duodenum, DMT1

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3
Q

What is the membrane transporter used by enterocytes to move iron into the blood?

A

Ferroportin

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4
Q

Where are the 3 major iron storage sites?

A

Liver, bone marrow, and macrophages

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5
Q

How does iron form free radicals?

A

Fenton reaction

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6
Q

What is normal %sat of iron?

A

33

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7
Q

What does serum ferritin reflect?

A

iron stores in the macrophages and liver

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8
Q

What is more readily absorbed Fe2+ or Fe3+?

A

2+

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9
Q

Why does gastrectomy lead to iron deficiency?

A

Acid aids absorption by favoring 2+ form

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10
Q

What is a common cause of iron deficiency in the elderly in developing countries?

A

Hookworm (Ancylostoma duodenale and Necator americanus)

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11
Q

What are the 4 stages of iron deficiency anemia?

A

1 Depletion of storage iron
2 depletion of serum iron
3 normocytic anemia
4 microcytic anemia

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12
Q

What are 3 clinical features of iron deficiency?

A

anemia, koilonychia (spoon shaped nails), and pica

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13
Q

What are the lab findings of iron deficiency anemia?

A

microcytic, hypochromic RBCs, increase RDW, decreased ferritin, increased TIBC, decreased serum Fe, decreased sat, increased free erythrocyte protoporphyrin.

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14
Q

What is Plummer Vinson Syndrome?

A

iron deficiency anemia with esophageal web and atrophic glossits, presents as anemia, dysphagia, and beefy red tongue.

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15
Q

What is responsible for anemia of chronic disease?

A

Chronic disease results in the production of acute phase reactants including hepcidin which causes iron sequestration by limiting iron transfer from macrophages to erythroid precursors and suppressing EPO production.

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16
Q

What are the laboratory findings in anemia of chronic disease?

A

increased ferritin, decreased TIBC, decreased serum iron, decreased saturation, increased free erythrocyte protoporphyrin.

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17
Q

Describe heme synthesis

A

ALAS converts succinyl CoA to ALA using B6
ALAD converts ALA to Porphobilinogen
Porphobilinogen gets converted into Protoporphyrin
Ferrochelatase attaches protoporphyrin to iron in mitochondria.

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18
Q

What are sideroblasts?

A

Iron laden macrophages that cluster in a ring around the nucleus

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19
Q

What defect is most common in congenital sideroblastic anemia?

A

ALAS (rate limiting)

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20
Q

What are some acquired causes of sideroblastic anemia?

A

Alcoholism leads to mitochondrial poisoning and decreased synth of protoporphyrin
Lead poisoning inhibits ALAD and ferrochelatase
Vit B6 deficiency common seen as side effect of isoniazid treatment for Tb

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21
Q

What chromosome is the alpha gene on?

A

16

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22
Q

What type of mutations are common in alpha thalassemia?

A

deletions

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23
Q

Name the consequences of increase deletions (1-4) of the alpha globin gene

A

1 - asymptomatic
2- mild anemia with increased RBC
Cis - asians
Trans - africans
3- Severe anemia; beta chains form tetramers (HbH) that damage RBCs
4- lethal in utero (hydrops fetalis); gamma chains form tetramers (HB barts) that damage RBCs

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24
Q

What type of mutations are common in beta thalassemia?

A

Gene mutations (point mutations in promoter or splicing sites) results in absent or diminished production

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25
Q

What chromosome is the beta gene on?

A

11

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26
Q

What is the genotype and symptoms of beta thalassemia minor. (what does smear and electrophoresis show?)

A

B/B+ microcytic hypochromic anemia with target cells. electrophoresis shows slightly decreased HbA with increased HbA2 and HbF

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27
Q

What is the genotype and symptoms of beta thalassemia major?

A

B0B0 unpaired alpha chains precipitate and damage RBCs resulting in ineffective erythropoiesis and extravascular hemolysis.
Massive erythroid hyperplasia results in expansion in skull and facial bones.
extramedullary hematopoiesis leads to hepatosplenomegaly and risk of aplastic crisis with parvovirus infection.

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28
Q

What does the blood smear and electrophoresis show in beta thalassemia major?

A

microcytic hypochromic RBCs with target cells and nucleated RBCs. electrophoresis shoes HbA2 and HbF and little or no HbA

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29
Q

In megaloblastic anemia, what effects are seen in other cells in the body other than RBCs?

A

hypersegmented neutrophils, and megaloblastic change in rapidly dividing epithelial cells.

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30
Q

What are some other causes of macrocytic anemia?

A

Alcoholism, liver disease, and drugs (eg 5-FU)

however with these causes you do not see hypersegmented neutrophils or change in rapidly dividing epithelial cells.

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31
Q

Where does dietary folate come from? Where is it absorbed? Does the body have large stores?

A

Green veggies and some fruits. Absorbed in the jejunum. Body stores are minimal.

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32
Q

What are some causes of folate deficiency?

A

poor diet (alcoholic elderly), increased demand (pregnancy, cancer, and hemolytic anemia), folate antagonists.

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33
Q

What are the clinical and laboratory findings of folate deficiency?

A

macrocytic RBCs and hypersegmented neutophils, glossitis, decreased serum folate, increased serum homocysteine, and normal methylmalonic acid.

34
Q

Describe the digestion and absorption of B12?

A

B12 is freed from binding proteins in food through the actions of pepsin in the stomach and binds to salivary protein haptocorrin. pancreatic proteases in the duodenum release B12 from haptocorrin and allow it to bind to intrinisic factor secreted by parietal cells in the stomach. It is then absorbed in the distal ileum receptor for intrinsic factor is called cubilin.

35
Q

What is pernicious anemia?

A

autoimmune destruction of parietal cells leading to poor absorption of B12 and megaloblastic anemia.

36
Q

What are some causes of B12 deficiency?

A

pancreatic insufficiency. damage to terminal ileum ( crohn’s disease or diphyllobothrium latum- fish tapeworm); dietary deficiency is rare except in vegans.

37
Q

What are the laboratory and clinical findings of B12 deficiency?

A

macrocytic RBCs and hypersegmented neutrophils, glossitis, subacute combined degeneration of the spinal cord due to build up of methylmalonic acid (poor proprioception and vibratory sensation (posterior column) and spastic paresis (lateral column)). decreased serum B12, increase homocysteine and methylmalonic acid.

38
Q

What is a normal reticulocyte count?

A

1-2%

39
Q

What is a corrected count? and what level does it reach in a properly functioning marrow during anemia?

A

reticulocyte count X hct/45

>3%

40
Q

What are the clinical and laboratory findings in extravascular hemolysis?

A

anemia with splenomegaly, jaundice due to unconjugated bilirubin, and increase risk for bilirubin stones. Also marrow hyperplasia with corrected count >3%

41
Q

What are the clinical and laboratory findings of intravascular hemolysis?

A

hemoglobinemia, hemoglobinuria, hemosiderinuria (Few days later), decreased serum haptoglobin.

42
Q

What is the inherited defect in hereditary spherocytosis?

A

RBC cytoskeleton membrane tethering proteins, most commonly ankyrin, spectrin and band3

43
Q

How are spherocytes formed in hereditary spherocytosis?

A

Membrane instability leads to blebs which are removed in the spleen.

44
Q

what type of anemia is hereditary spherocytosis? what leads to the anemia?

A

Normocytic extravascular. Spherocytes cannot maneuver through splenic sinusoids.

45
Q

What are the clinical and laboratory findings in hereditary spherocytosis?

A

Spherocytes with loss of central pallor. increased RDW and MCHC. Splenomegaly withe jaundice. increased risk for aplastic crisis with parvo B19.

46
Q

How is hereditary spherocytosis diagnosed?

A

Osmotic fragility test in hypotonic solution.

47
Q

What is the treatment in hereditary spherocytosis? what begins to appear in peripheral smears?

A

Splenectomy. Howell-Jolly bodies (Fragments of nuclear material ) which are normally removed by the spleen.

48
Q

What is the mutation in sickle cell anemia? What inheritance pattern?

A

AR, mutation in beta chain; glutamic acid to valine.

49
Q

What increases the risk of sickling in sickle cell anemia?

A

Hypoxia, dehydration, acidosis

50
Q

What does extravascular hemolysis in sickle cell lead to?

A

anemia, jaundice, increased risk of bili stones

51
Q

What does the limited intravascular hemolysis in sickle cell lead to?

A

decreased haptoglobin, target cells

52
Q

What are the common presenting signs in infants of sickle cells anemia?

A

Vaso-occlusion leading to dactylitis (swollen hands and feet due to infarcts in the bones)

53
Q

What causes autosplenectomy in sickle cell? what are the consequences?

A

Infarcts in the spleen. increased risk of infection with capsulated organisms such as steptococcus pneumoniae and haemophilus influenzae due to lack of antibody production (children should be immunized). increased risk of salmonella paratyphi osteomyelitis. howell jolly bodies in smears.

54
Q

What causes renal papillary necrosis in sickle cell? what are the consequences?

A

vaso-occlusion in the kidney results in gross hematuria and proteinuria.

55
Q

What is one symptom that can be seen in sickle cell trait involving the kidney?

A

Sickling doesnt usually occur except in extreme hypoxia and hypertonicity of renal medulla which results in microinfarction leading to microscopic hematuria and eventually a decreased ability to concentrate urine

56
Q

What test can be used to detect both sickle cell and trait?

A

Metabisulfite.

57
Q

What mutation is seen in hemoglobin C, what does it present with, what is seen on smears?

A

glutamic acid to lysine, mild anemia due to extravascular hemolysis and HbC crystals seen on smear.

58
Q

What type of anemia is Paroxysmal nocturnal hemoglobinuria? What causes it?

A

Intravascular normocytic. Acquired defect in myeloid stem cells resulting in absent GPI which anchors DAF and MIRL to the membrane rendering them susceptible to destruction by compliment.

59
Q

What CD marker is DAF?

A

CD55

60
Q

What does intravascular hemolysis in PNH lead to?

A

hemoglobinuria, hemoglobinemia, hemosiderinuria

61
Q

What cells are affected in PNH?

A

RBCs WBCs and Platelets

62
Q

What test is used to screen for PNH what is used to confirm?

A

Sucrose test to screen (activates compliment). confirmatory is acidified serum test or flow cytometry for DAF (CD55)

63
Q

What is the main cause of death in PNH?

A

thrombosis of hepatic, portal or cerebral veins dues to destroyed platelets releasing cytoplasmic contents into circulation.

64
Q

What are some complications of PNH?

A

iron deficiency anemia and AML (10%)

65
Q

How is G6PD deficiency inherited? What type of anemia is it?

A

X-linked recessive. normocytic intravascular

66
Q

How does G6PD deficiency lead to oxidative stress?

A

decreased NADPH–> decrease reduced glutathione –> oxidative injury by H2O2

67
Q

What are the two variants of G6PD deficiency?

A

African - mild
Mediterranean - Severe
high carrier rate in both

68
Q

What does oxidative stress in G6PD deficiency lead to?

What symptoms does it lead to?

A

Hb precipitates as Heinz bodies which are removed from RBCs by macrophages in the spleen resulting in Bite Cells. Intravascular hemolysis presents with hemoglobinuria and back pain (bc hemoglobin is highly nephrotoxic)

69
Q

What studies are done to confirm G6PD deficiency?

A

Heinz prep to see heinz bodies and enzyme tests well after an episode.

70
Q

What type of antibody is involved in Immune hemolytic anemia of the warm agglutinin type? what are the symptoms

A

IgG binds in relatively warm temp of central body .and usually causes extravascular hemolysis membrane is consumed by macrophages resulting in spherocytes.

71
Q

What are the associated causes of IgG IHA?

A

SLE (most common), CLL, and certain drugs (Penicillin and cephalosporins)

72
Q

What is the treatment of IgG IHA?

A

cessation of offending drug, steroids, IVIG, and if necessary splenectomy.

73
Q

What type of antibody is involved in Immune hemolytic anemia of the cold agglutinin type? what are the symptoms

A

IgM binds and fixes complement in relatively cold extremities. RBCs inactivate compliment but residual C3b serves as an opsonin for splenic macrophages resulting in spherocytes. Extreme compliment activation can result in intravascular hemolysis.

74
Q

What infections are associated with IgM IHA?

A

Mycoplasma pneuoniae and infectious mononucleosis.

75
Q

What is used to diagnose IHA?

A

Coombs test direct or indirect.

76
Q

What are the major causes of micropathic hemolytic anemia?

A

microthrombi (TPP, HUS, DIC, HELLP), prosthetic heart valves, and aortic stenosis(calcified degenerative valve)

77
Q

What are the 3 main etiologies of anemia due to underproduction?

A

1 causes of micro and macrocytic anemia
2 renal failure - decreased EPO
3 damage to bone marrow precursor cells (may result in anemia or pancytopenia)

78
Q

What does parvovirus B19 do?

A

Infects progenitor red cells and temporarily halts erythropoiesis; leads to significant anemia in the setting of preexisting marrow stress

79
Q

What are some etiologies of aplastic anemia?

A

drugs or chemicals, viral infections, autoimmune damage

80
Q

What does a biopsy reveal in aplastic anemia?

A

fatty marrow

81
Q

What are the treatments for aplastic anemia?

A

cessation of any causative drugs and supportive care with transfusions and marrow stimulating factors. immunosuppression may be helpful as some idiopathic cases are due to abnormal T-cell activation with release of cytokines. May require bone marrow transplant

82
Q

What is a myelophthisic process?

A

Pathologic process that replaces bone marrow: hematopoiesis is impaired, resulting in pancytopenia.

My Pathoma Unit 2 (6 decks)

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