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Heme and Lymph Midterm > Chapter 14: Polycythemia and Bleeding Disorders > Flashcards

Chapter 14: Polycythemia and Bleeding Disorders Flashcards

1
Q

Polycythemia

A
  • abnormally high red cell count, usually with a corresponding increase in Hbg levle
  • may be relative when there is hemoconcentration due to decreased plasma volume, or absolute when there is an increase in the total red cell mass
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2
Q

Relative polycythemia

A

results from dehydration

-

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3
Q

stress polycythemia (Gaisbock syndrome)

A

affected individuals are usually hypertensive, opbese, and anxious (stressed)

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4
Q

Absolute polycythemia

A
  • primary when it results from and intrinsic abnormality of hematopoietic precursors a
  • secondary when the red cell progentiors are responding to increased levels of EPO
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5
Q

What is the most common cause of polycythemia?

A

polycythemia vera

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6
Q

What is polycythemia vera (PCV)

A

a myeloproliferative disorder associated wtih mutations that lead to EPO-independent growth of red cell progenitors

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7
Q

Prothrombin time (PT)

A

assesses the extrinsic and common coagulation pathways

  • the clotting of plasma after addition of exogenous source of tissue thromboplastin and Ca2+ ions is measured in seconds
  • a prolonged PT can result from deficiency or dysfunction of factor V, VII, X, prothrombin, or fibrinogen
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8
Q

Partial thromboplastin time (PTT)

A

assesses the intrinsic and common clotting pathways

  • clotting of plasma after addition of kaolin activates the contact dependent factor XII, and cephalin substitutes for platelet phospholipids
  • prolongation of PTT can be due to deficiency or dysfunction of factors V, VIII, IX, X, XI, or XII, prothrombin, or fibrinogen, or to interfering antibodies to phospholipid
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9
Q

Infections as a cause of bleeding

A
  • meningococcemia

- petechiae and purpura can be caused by this and if it’s not caught, the patient is fucked

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10
Q

drug rxns as a cause of bleeding

A

vascular inury mediated by deposition of drug-induced immune complexesin vessel walls
-leads to hypersensitivity vasculitis

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11
Q

Scurvy and Ehler-Danlos syndrome as a cause of bleeding

A
  • collagen defects

- weaken vessel walls

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12
Q

Henoch-Schonlein purpura as a cause of bleeding

A
  • systemic immune disorder of unknown cause
  • purpuric rash, colicky abdominal pain, polyarthralgia, and acute glomerulonephritis
  • deposition of circulating immune comlexes within vessels throughout the body and within the glomerular mesangial regions
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13
Q

hereditary hemorrhagic telangiectasia

-Weber-Osler-Rendu syndrome

A
  • autosomal dominant disorder that can be caused by mutations in at least five different genes
  • most of them modulate TGF-B signaling
  • Dilated tortuous blood vessels with thin walls that bleed readily
  • bleeding under the mucous membranes of the nose, tongue, mouth, and eyes, and throughout the GI tract
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14
Q

Perivascular amyloidosis

A

-can weaken blood vessel walls and cause bleeding

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15
Q

What is serious bleeding most often associated with?

A

hereditary hemorrhagic telangiectasia

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16
Q

Chronic immune thrombocytopenic purpura (ITP)

A

-caused by autoantibody mediated destruction of platelets
-diagnosis of primary chronic ITP is made only after secondary causes are excluded
-autoantibodies (IgG) against platelet membrane glycoproteins IIb-IIIa or Ib-IX in plasma
-

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17
Q

Morphology of ITP

A
  • marrow reveals a modestly increased number of megakaryocytes
  • peripheral blood often reveals abnormally large platelets
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18
Q

Clincal features of ITP

A
  • adult women younger than 40
  • pinpoint hemorrhages
  • eccymoses
  • PT and PTT are normal
  • if too severe, splenectomy will help
  • IV Ig or anti CD20 antibody (rituximab) are often effective in patients who relapse after a splenectomy
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19
Q

Acute Immune Thrombocytopenic Purpura

A
  • again, auto antibodies to platelets
  • its clinical features and course are distinct
  • mainly a disease of childhood
  • Unlike chronic ITP, acute ITP is self limited
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20
Q

Drug induced Thrombocytopenia

A

quinine, quinidine, and vancomycin
-they bind platelet glycoproteins and in one way or another create antigenic determinants that are recognized by antibodies

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21
Q

Heaprin-induced thrombocytopenia (HIT)

A
  • type 1: occurs rapidly after onset of therapy… sometimes resolves on its own
  • type 2: less common but of much greater clinical significance… 5-14 days after therapy begins
  • paradoxically, often leads to life-threatening venous and arterial thrombosis
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22
Q

HIV associated thrombocytopenia

A

CD4 and CXCR4 are found on megakaryocytes

  • the autoantibodies opsonize platelets, promoting their destruction by mononuclear phagocytes in the spleen and elsewhere
  • one of the most common hematologic manifestations of HIV infection
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23
Q

Thrombocytopenic Purpura (TTP)

A
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24
Q

HUS

A

also associated with microangiopathic hemolytic anemia and thrombocytopenia but is distinguished by…..THE ABSENCE OF NEURO SYMPTOMS, THE PROMINENCE OF ACUTE RENAL FAILURE, AND ITS FREQUENT OCCURRENCE IN CHILDREN

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25
Q

Thrombotic microangiopathy

A

encomasses a spectrum of clinical syndromes that includes TTP and HUS

  • caused by insults that lead to excessive activation of platelets, which deposit as thrombi in small blood vessels
  • the consumption of platelets is what leads to thrombocytopenia
  • PT and PTT are usually normal
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26
Q

In TTP, what is the enzyme that is deficient?

A

ADAMTS13

  • normally degrades vWF
  • vWF promotes platelet activation and aggregation without it
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27
Q

What is normal in HUS that isn’t in TTP?

A

ADAMTS13

  • but the typical kind strongly associated with gastroenteritis caused by E. coli … elaborates shiga like toxin
  • children and older adults
  • bloody diarrhea
  • atypical HUS: defects in complement factor H, membrane cofactor protein (CD46), or factor I…they normally act to prevent excessie activation of the alternative complement pathway
28
Q

Bernard-Soulier syndrome

A
  • defective adhesion of platelets
  • inherited deficiency of platelet membrane glycoprotein complex Ib-IX, a receptor for vWF
  • severe bleeding tendency
29
Q

Glanzmann thrombasthenia

A
  • defective AGGREGATION of platelets
  • deficiency or dysfunction of glycoprotein IIb-IIIa, and integrin that participates in “bridge formation” between platelets by binding fibrinogen
  • severe bleeding tendency
30
Q

How are disorders of platelet secretion characterized?

A

-defective release of certain mediators of platelet activation, such as thromboxanes and granule-bound ADP

31
Q

What is an obvious acquired defect of platelet function?

A

aspirin and other NSAID ingestion

32
Q

What are the 2 most common inherited disorders of bleeding?

A
  • hemophilia A: involves factor 8 (ayyyyyT)

- von Willebrand disease: involves vWF

33
Q

What does factor VIII do?

A

it’s a cofactor for factor IX

-factor IX converts factor X to Xa

34
Q

What is the most important function of vWF

A

to promote the adhesion of platelets to the subendothelial matrix
-occurs through bridging interactions between platelet glycoprotein Ib-IX, vWF and matrix components like collagen

35
Q

Von Willebrand Disease

A
  • the most common inherited bleeding idsorder of humans

- spontaneous bleeding from mucous membranes

36
Q

Type 1 vW disease

A
  • auto dominant
  • mild to moderate vWF deficiency
  • 70% of all cases
37
Q

Type 3 vW disease

A
  • auto recessive
  • very low levels of vWF
  • severe clinical manifestations
  • vWF has effect on stability of factor VIII… so some of it will look like hemophilia
38
Q

Type 2 vW disease

A
  • characterized by qualitative defects in vWF
  • types 1 and 3 are involved with quantitative defects in vWF
  • auto dominant
  • mild to moderate bleeding
  • type 2A is most common
39
Q

In which types of vW disease is the PTT prolonged?

A

Types 1 and 3

-the quantitative ones

40
Q

Hemophilia A (factor 8 deficiency)

A
  • the most common hereditary disease associated with life-threatening bleeding, is caused by mutations in factor VIII, an essential cofactor for factor IX in the coagulation cascade
  • X-linked recessive
  • severity correlates with the level of factor VIII activity
  • the most severe deficiencies result from an inversion involving the X chromosome
41
Q

Where are the hemorrages at in Hemophilia A?

A

“particularly in the joints”

  • hemarthroses
  • petechiae are characteristically absent
42
Q

How does the PT and PTT look like in Hemophilia A?

A
  • long PTT

- normal PT

43
Q

What is another name for hemophilia B?

A

Christmas disease

-factor IX deficiency

44
Q

What does factor IX deficiency (hemophilia B) look like?

A

just like factor VIII deficiency

  • X linked recessive
  • long PTT and normal PT
  • diagnosis is only possible by assay of factor levels
45
Q

Disseminated Intravascular Coagulation (DIC)

A
  • excessive activation of coagulation and the formation of thrombi in the microvasculature of the body
  • consumption of platelets, fibrin, and coagulation factors and, secondarily, activation of fibrinolysis
  • *so, it’s weird because there are microthrombi and hemorrhage at the same time…. *
46
Q

What are the two major mechanisms that trigger DIC?

A
  1. ) release of TISSUE FACTOR or other, poorly characterized procoaagulants, into the circulation
  2. ) widespread injury to the endothelial cells (like burns or something like that)
47
Q

What is DIC most likely associated with?

A

obstetric complications, malignant neoplasms, sepsis, and major trauma

48
Q

What is released that causes DIC in massive trauma, extensive surgery, and severe burns?

A

Tissue factor

-remember, that’s bad in this chapter….

49
Q

Which cancers are most frequently associated with DIC?

A

acute promyelocytic leukemia and adenocarcinomas of the lung, pancreas, colon, and stomach

50
Q

What are the possible consequences of DIC?

A

1.) widespread deposition of fibrin in the microcirculation… leads to ischemia and microangiopathic hemolytic anemia (when Red cells try to squeeze through the narrowed microvasculature)

51
Q

Where are thrombi most often found in DIC?

A
52
Q

What are some other morphologic features of DIC?

A

-bilateral renal cortical necrosis
-hyaline membranes in the lungs… looks like ARDS
-

53
Q

Which form of DIC is the one with giant hemangiomas?

A

Kasabach-Merritt syndrome

-thrombi form within the neoplasm because of stasis and recurrent trauma to fragile blood vessels

54
Q

If there is DIC, what is the most likely etiology?

A

obstetric complications

55
Q

What is Acute DIC associated with?

A

a shit ton of bleeding

56
Q

What is Chronic DIC associated with?

A

more clotting

-thrombotic complications

57
Q

What is the most common complication of transfusion?

A

febrile nonhemolytic reaction

  • fever and chills, sometimes with mild dyspnea
  • within 6 hours of a transfusion of red cells or platelets
58
Q

How are allergic reactions tied into complications of transfusion?

A
  • most likely occur in patients with IgA deficiency

- the reaction itself is triggered by IgG antibodies that recognize IgA in the infused blood product

59
Q

What are urticarial allergic reactions?

A
  • triggered by allergen in the donated blood
  • recognized by IgE antibodies in the recipient
  • these are MORE COMMON!!!
  • symptoms are generally mild and respond to antihistamines most of the time
60
Q

Hemolytic reactions

A
  • usually caused by preformed IgM antibodies against donor red cells that fix complement
  • fever, shaking, chills, and flank pain appear rapidly
61
Q

What do hemolytic reactions most commonly stem from?

A

an error in patient identification or tube labeling

-leads to ABO incompatible unit of blood

62
Q

Delayed hemolytic reactions

A

caused by antibodies that recognize red cell antigens that the recipient was sensitized to previously, for example, through a prior blood transfusion

  • typically caused by IgG antibodies
  • positive direct Coombs test
63
Q

Transfusion-related acute lung injury (TRALI)

A

severe, frequently fatal complication in which factors in a transfused blood product trigger the activation of neutrophils in the lung microvasculature

  • look for pre-existing lung disease
  • 2 hit hypothesis: 1.) sequestration and sensitization of neutrophils in the microvasculature of the lung
    2. ) transfused blood product activates the primed neutrophils
  • more likely to occur following transfusion of products containing high levels of donor antibodies…. like fresh frozen plasma and platelets
64
Q

What do the bilateral pulmonary infiltrates seen in TRALI NOT respond to?

A

diuretics

-sidenote, don’t give plasma this to a multiparous woman

65
Q

Why does bacteria grow on platelets before they are transferred into a person?

A

they must be stored at room temperature, conditions that are favorable for bacterial growth

Heme and Lymph Midterm (11 decks)

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