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Skin, Blood & Lymph Exam #1 > RBC Pathology 2 > Flashcards

RBC Pathology 2 Flashcards

1
Q

Which kind of enzymes make up the mammalian coagulation system?

A

Serine protease enzymes

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2
Q

Which clotting pathway is the one of primary importance?

A

Tissue factor (extrinsic) pathway

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3
Q

Which pathway is measured by PTT and PT, respectively?

A

PTT - intrinsic pathway.

PT - extrinsic pathway.

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4
Q

What is used to monitor coumadin?

What is used to monitor heparin?

A

Coumadin: PT

Heparin: PTT

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5
Q

What are the vitamin K-dependent factors? (4)

A

Factors II, VII, IX, X

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6
Q

How are platelet counts done?

What may suggest a MPD?

A

They are obtained using an electric platelet counter.

Abnormal platelet counts should be confirmed by inspection of a peripheral blood smear, because clumping of platelets can cause “spurious thrombocytopenia” and may be indicative of a MPD (ET).

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7
Q

How do most bleeding disorders present?

A

They present with small hemorrhages (petechiae or purpura) in the skin or mucous membranes, particularly the gingiva.
They can occasionally cause more significant hemorrhages into joints, muscles, etc. or manifest as menorrhagia, nosebleeds, GI bleeds, or hematuria.

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8
Q

What 3 physiologic abnormalities can result in excessive bleeding?

A

Vessel fragility

Decreased/dysfunctional platelets

Deranged coagulation

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9
Q

What disorders/processes may cause bleeding due to vessel wall fragility? (6)

A

Infections (meningitis, IE, rickettsia, etc.)

Drug reactions

Scurvy and Ehlers-Danlos syndrome (collagen defects)

Henoch-Schonlein purpura

Hereditary hemorrhagic telangiectasia (most often associated with serious bleeding)

Perivascular amyloidosis

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10
Q

The causes of thrombocytopenia fall into which 4 categories?

A
  1. Decreased platelet production: results from conditions that suppress marrow output (anemia, malignancy, HIV).
  2. Decreased platelet survival - immune (alloantibodies in pregnancy) vs. non-immune (DIC).
  3. Sequestration.
  4. Dilution: massive transfusions may result in dilutional thrombocytopenia.
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11
Q

What is the cause of chronic immune thrombocytopenic purpura (ITP)?

What are some secondary associations with chronic ITP?

What usually improves the thrombocytopenia?

What is seen on smear? What is seen in the BM?

A

Autoantibody-mediated destruction of platelets. The antibodies are directed against platelet membrane glycoproteins.

SLE, HIV and B-cell neoplasms (CLL).

Splenectomy.

Abnormally large platelets (megathrombocytes); mildly increased number of megakaryocytes.

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12
Q

What sex and age is most common to be diagnosed with chronic ITP?

What is the presentation?

What is the PT and PTT like?

How is it diagnosed?

A

Adult females younger than 40 y/o (3:1 F:M).

Insidious onset with bleeding into the skin and mucosal surfaces.

PT and PTT are both normal.

It is a diagnosis of exclusion and is only made after other causes of thrombocytopenia are ruled out.

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13
Q

What PE finding should suggest a malignancy instead of chronic ITP?

A

Splenomegaly and lymphadenopathy

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14
Q

What is the pathogenesis of acute ITP?

What age is most common?

When do symptoms appear?

What is the progression of acute ITP?

A

The same as chronic ITP; autoantibodies against platelets.

Childhood, M = F.

Symptoms appear 1-2 weeks after a self-limited viral illness, which triggers the development of autoantibodies.

Usually it is self-resolving within 6 mo. (unlike chronic ITP). Glucocorticoids should be given only if thrombocytopenia is severe.

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15
Q

What drugs are commonly associated with drug-induced thrombocytopenia? (3)

A

Quinine
Quinidine
Vancomycin

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16
Q

What is the difference between type 1 and type 2 heparin-induced thrombocytopenia (HIT)?

A

Type 1: occurs quickly after initiation of therapy. It generally resolves quickly and is not of much clinical importance.

Type 2: less common. Begins 5-14 days after initiation of therapy. It results in severe and life-threatening venous and arterial thromboses (even despite the thrombocytopenia).

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17
Q

What 2 mechanisms contribute to HIV-associated thrombocytopenia?

Why are megakaryocytes implicated in HIV?

How does HIV predispose someone to development of autoantibodies?

A

(1) Impaired platelet production and (2) increased destruction of platelets.

Megakarycytes express CD4 and CXCR4 (R and co-R for HIV) and can become infected, which leads to apoptosis and impaired platelet production.

It causes B-cell hyperplasia and dysregulation which predisposes someone to developing autoantibodies, sometimes against glycoprotein IIb-IIIa complexes.

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18
Q

What is the pentad of symptoms in thrombotic thrombocytopenic purpura (TTP)? (5)

A 
Fever
Thrombocytopenia
Microangiopathic hemolytic anemia
Transient neurological defects
Renal failure
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19
Q

What are the symptoms in hemolytic-uremic syndrome (HUS)? (3)

What patients is it seen in most?

A

Microangiopathic hemolytic anemia
Thrombocytopenia
Acute renal failure

Kids

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20
Q

What is the the major consequence of both TTP and HUS?

How is it different than DIC?

A

Microangiopathic hemolytic anemia and widespread organ dysfunction.

Activation of the clotting cascade is not of primary importance and as a result, PT and PTT are normal.

21
Q

What is the typical cause of HUS?

What is the atypical cause?

A

Typical: E. coli strain O157:H7 (Shiga-like toxin)

Atypical: alternative complement pathway inhibitor deficiencies (complement factor F, membrane cofactor protein (CD46) or factor I).

22
Q

What causes TTP?

A

Deficiency of ADAMTS13 (inherited or acquired).

23
Q

Inherited disorder of platelet function are grouped into what 3 groups?

A
  1. Defects in adhesion
  2. Defects of aggregation
  3. Disorders of platelet secretion (release reaction)
24
Q

What is the pathogenesis of Bernard-Soulier syndrome?

What is the inheritance and defective protein?

What is the major symptom?

What is characteristically seen in peripheral blood?

A

There is defective adhesion of platelets to the subendothelial matrix.

AR - platelet membrane glycoprotein complex Ib-IX (receptor for vWF).

Variable, often severe bleeding.

Giant platelets.

25
Q

What is the pathogenesis of Glanzmann thrombasthenia?

What is the inheritance and defective protein?

What is the major symptom?

How do the platelets appear on in peripheral blood?

A

There is defective platelet aggregation.

AR - dysfunction of glycoprotein IIb-IIIa (helps form a “bridge” between platelets by binding fibrinogen.

Variable bleeding - mild to severe.

The platelets are typically normal appearing and in normal quantity.

26
Q

What 2 mediators of platelet activation, if defective, can cause disorders due to platelet secretion?

A

Tx-A and granule-bound ADP

27
Q

What is the most common cause of acquired defects of platelet function?

What is another, less common, cause?

A

Aspirin/NSAID ingestion.

Uremia.

28
Q

Unlike bleeding seen in thrombocytopenia, bleeding due to coagulation factor deficiencies often occurs… (3)

A

Into the GI tract (melena), urinary tract (hematuria) and weight-bearing joints (hemarthrosis).

Ex: patient who oozes blood for days after a tooth extraction; mild knee stress causes hemarthrosis.

29
Q

How many factors are implicated in inherited vs. acquired disorders?

A

Inherited disorders tend to include only 1 factor.

Acquired disorders tend to include multiple factors.

30
Q

What are the 2 most common inherited disorders of bleeding?

A

Hemophilia A (factor VIII) - most common disorder associated with life-threatening bleeding.

von Willebrand disease (vWF) - most common overall.

31
Q

What is the function of vWF?

A

It binds factor VIII in circulation and stabilizes it (increases its half-life).

32
Q

Which “types” of von Willebrand disease are only quantitative?

Which one is qualitative?

A

Type 1 and type 3.

Type 2.

33
Q

Briefly describe the following types of vWD:

Type 1

Type 2

Type 3

A

Type 1: mild to moderate vWF deficiency. Makes up 70% of cases. It is a mild form of the disease.

Type 2: vWF is expressed in normal amounts, but is assembled poorly. It makes up 25% of cases and is associated with mild to moderate bleeding.

Type 3: very low levels of vWF and severe bleeding.

34
Q

What is the inheritance of each type of vWD?

A

Type 1 and 2 are AD.

Type 3 is AR.

35
Q

Is there an abnormality in platelet concentration in vWD?

What is used to measure vWF in serum? What is the concentration of it?

What can be given to patients with vWD who experience hemostatic problems?

A

Platelet concentration is normal.

Ristocetin cofactor activity is reduce.

Desmopressin, which stimulates vWF release of with infusions containing factor VIII and vWF.

36
Q

Which types of vWD show a prolongation of PTT?

A

Type 1 and type 3.

37
Q

What is the function of ADAMTS13?

A

It cleaves vWF

38
Q

What is the inheritance of hemophilia A?

What can be used to determine the clinical severity of the disease?

What genetic change occurs in the most severe deficiencies?

A

X-linked recessive.

Factor VIII levels - severity is a range.

Inversion involving the X chromosome that completely abolishes the synthesis of factor VIII.

39
Q

What PE finding is usually absent in hemophilia A?

What symptoms may occur?

What is the PTT and PT?

How is it treated?

A

Petechiae.

Easy bruising, massive hemorrhage after trauma/operation, hemarthrosis, spontaneous hemorrhages.

PTT is prolonged and PT is normal.

Treated with infusions of recombinant factor VIII. About 15% of patients develop autoantibodies to factor VIII post-treatment (acquired hemophilia).

40
Q

What is another name for hemophilia B?

What factor is implicated?

If the deficiency is great enough, it may lead to a disorder that is clinically indistinguishable from what other disorder?

A

Christmas disease

Factor IX deficiency.

Hemophilia A

41
Q

What is the inheritance of hemophilia B?

What is the PTT and PT?

How is it diagnosed? How is it treated?

A

X-linked recessive.

PTT is prolonged and PT is normal.

It is diagnosed only via assay of factor levels. It is treated with infusions of recombinant factor IX.

42
Q

What 2 mechanisms can trigger DIC?

A

Release of tissue factor.

Widespread injury to endothelial cells.

43
Q

What is acute DIC most associated with?

What is chronic DIC most associated with?

A

Acute DIC: obstetric complications or major trauma.

Chronic DIC: cancer

44
Q

What is the most commona complication of transfusion?

A

A febrile non-hemolytic reaction, which takes the form of fever and chills, sometimes with mild dyspnea, within 6 hrs. of transfusion of RBCs or platelets.

Symptoms are usually short-lived and respond to treatment.

45
Q

What causes a severe reaction from transfusions?

Which patients are they most likely to occur in?

A

Blood products containing certain antigens are given to previously sensitized recipients.

Patients with IgA deficiency - it is triggered by IgG antibodies that recognize IgA in the infused blood.

46
Q

What occurs in urticarial allergic reactions?

A

The presence of an allergen in the donated blood product is recognized by IgE antibodies in the recipient.

It tends to respond to antihistamines and does not require discontinuation of the transfusion.

47
Q

What causes acute hemolytic reactions after transfusions?

What are acute symptoms?
What are chronic symptoms?

What test is positive?

A

Preformed IgM against donor red cells that fix complement. It is usually due to an error in patient identification or tube labeling.

Fever, shaking, chills and flank pain occur rapidly.
DIC, shock, ARF and occasionally death.

Direct Coombs test is usually positive.

48
Q

What causes delayed hemolytic reactions occur with blood transfusions?

What test is positive?

A

Antibodies that recognize red cell sntigens that the patient was previously sensitized to (prior infusions).

Direct Coombs test is positive.

49
Q

What is transfusion-related acute lung injury (TRALI)?

What antibodies are most associated with it?
Which patients are most likely to have these specific antibodies?

What products is it most likely to occur with?

What is the clinical presentation?

A

A severe, often fatal complication in which factors in transfused blood trigger activation of neutrophils in the lung microvasculature.

Antibodies binding MHC class I antigens.
Multiparous women (they don't generate antibodies against foreign MHC expressed by the fetus).

Products with high levels of donor antibodies like FFP and platelets.

Dramatic onset with sudden respiratory failure during or soon after transfusion. Fever, hypotension and hypoxemia may also ensue.

Skin, Blood & Lymph Exam #1 (12 decks)

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