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Hematology Block 2 > Hemorrhagic Disorders > Flashcards

Hemorrhagic Disorders Flashcards

1
Q

What are the two distinct functions of VWF in hemostasis?

A
  1. It acts as the fuzzy part of velcro, helping platelets stick down to the injured subendothelium.
  2. Ferries FVIII around the circulation—protecting it from degradation
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2
Q

How are Factor VIII and VWF related in plasma?

A

Noteworthy that VWF is generated from megakaryocytes, which also generate platelets.

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3
Q

What is the most common inherited bleeding disorder?

A

Von Willebrand Disease

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4
Q

What is the inheritance pattern of VWF?

A

Autosomal co-dominant

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5
Q

80% of patients with VWD have Type ___. Explain.

A

Type 1

This is a quantitative disorder (levels of VWF are about 30% of normal)

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6
Q

What are the clinical manifestations of VWD?

A

Mucocutaneous bleeding (esp. heavy menstrual bleeding)

Excessive bleeding after surgery (especially on mucosal surfaces)

NOT joint and muscle bleeding.

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7
Q

____ is found in 75-95% of women with VWD

A

Menorrhagia

Fibroids may “unmask” VWD

FHx may “mask” severity of problem if all girls are affected

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8
Q

What are the lab findings associated with Type 1 VWD? (include PT, aPTT, TCT, PFA-100, Factor VIII level, VWF antigen, and VWF activity)

A
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9
Q

Why is it difficult to test for VWD?

A

•VWD levels may vary within a single individual

  • Increase with stress, anxiety, exercise
  • Change with time of menstrual cycle
  • VWD levels can be increased by estrogen in OCPs and HRT
  • VWD levels are increased in pregnancy
  • VWF activity assays are difficult to perform and are affected by specimen collection and processing
  • VWD levels can vary with ABO type
  • Type O makes VWF low
  • Uncertain clinical significance.
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10
Q

What 3 criteria have to be assessed to diagnose VWD?

A

Personal history of abnormal bleeding

Family history of abnormal bleeding

Low levels of VWF (<30%)

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11
Q

How is VWD treated?

A

•Hormonal manipulations – esp. for menorrhagia

•Desmopressin (DDAVP)

  • Releases FVIII and VWF from preformed stores in the endothelial cells
  • Tachyphylaxis with repeat doses (stores have to fill back up)
  • Hyponatremia with prolonged use

•Antifibrinolytics – stabilize clot on mucosal surfaces

  • Tranexamic acid and epsilon aminocaproic acid are used

•Blood products and clotting factors

  • Plasma-derived factor concentrates that contain FVIII and vWF.

•A new recombinant VWF product has just been introduced (given intravenously)

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12
Q

Hemophilia A is caused by a deficiency in _____

A

Factor VIII

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13
Q

Hemophilia B is caused by a deficiency in ____

A

Factor IX

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14
Q

Compare/contrast lab findings for Hemophilia A and Type 1 VWD. (Include PT, aPTT, TCT, PFA-100, Factor VIII level, VWF antigen, VWF activity)

A
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15
Q

How does symptom severity/disease manifestation of Hemophilia vary with Factor VIII or IX level?

A
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16
Q

Alex Atsalotofblood has hemophilia A and an aPTT of 50 sec. Billy Bleedsalot has hemophilia B and an aPTT of 50 sec. Normal is 25-35. We mix Alex’s and Billy’s plasma together. What is the resultant aPTT?

A

About 30 seconds

Hemophilia A is deficient in Factor VIII

Hemophilia B is deficient in Factor IX

A patients will have normal IX, B patients will have normal VIII, so mixed together, they can supply all the normal factors needed for a normal PTT test. Can correct for each other in this test.

17
Q

Hemophilia A is a disorder of ____ hemostasis. VWD is a disorder of ____ hemostasis.

A

Hemophilia A is a disorder of secondary hemostasis.

VWD is a disorder of primary hemostasis.

18
Q

Where to people with hemophilia typically bleed?

A
  • Hemarthrosis (70-80% of all bleeding episodes) - bleeding into joints
  • Bleeding into muscles
  • CNS bleeding
  • Retroperitoneal bleeding
  • GU bleeding (Can be hard to control - a lot of fibrinolytic activity in urinary collection system. We can’t use anti-fibrinolytic agents because if we clot off the ureters, urine can’t exit kidney and kidney develops hydronephrosis which is BAD)
  • Oro- and nasopharynx
19
Q

Orthopedic complications of hemophilia:

A
  • Recurrent joint bleeds
  • Synovitis
  • Cartilage damage
  • Accelerated arthritis
  • Muscle wasting, flexion contractures
  • Need for joint replacement
20
Q

How is Hemophilia treated?

A

•DDAVP - Used for mild hemophilia A (not B) before invasive procedures or to treat bleeding. Usually can only increase FVIII by 3 fold or so. [This releases FVIII (and WVF) from preformed stores in the endothelial cells - can’t use regularly b/c of tachyphylaxis and hyponatremia]

•Replace deficient factor

  • Source of plasma
    • Plasma-derived
    • Recombinant

•Timing of delivery

  • •Prophylactic (prevent bleeding)
  • •On-demand (treat bleeding)
21
Q

Hemophilia and Infections:

A
  • In the 1980′s, approximately 90% of people with severe hemophilia were infected with the HIV virus
  • Almost all patients with hemophilia who used factor products before 1988 were infected with Hepatitis C (HCV).
  • In 2009, a UK patient with hemophilia was diagnosed at death with variant CJD (Creutzfeld Jakob disease) —felt to have infected the patient via infusion of clotting factor
22
Q

Hemophilia and Inhibitors:

A
  • Some proportion of patients with hemophilia will develop neutralizing antibodies to clotting factor concentrates. These are inhibitors.
  • 3-fold more common hemophilia A than Hemophilia B
  • More common with certain mutations
  • More common in non-Caucasians
  • Increases cost, decreases QOL
23
Q

A woman presents with abnormal bleeding. An aPTT is prolonged and corrects with mixing study. Factor VIII level is 10%. Could she have VWD, Hemophilia A, or both?

A

Both

(although less common, women can have hemophilia - could have Turner’s Syndrome (one X) with hemophilia, could have a homozygous recessive mutation, or could be a carrier with selective X inactivation/lyonization (most common).

24
Q

A woman presents with abnormal bleeding. An aPTT is prolonged and corrects with mixing study. Factor VIII level is 10%. The PFA-100 is normal. Could she have Hemophilia A, VWD, or both?

A

Hemophilia A

(PFA-100 would be prolonged in VWD, because this is a disease of primary hemostasis)

25
Q

How is a woman defined as a carrier of hemophilia?

A

Defined as a woman who:

  • Is the biologic daughter of a man with hemophilia A or B
  • Is the mother of two or more sons with hemophilia
  • Has a brother and a son with hemophilia
26
Q

Emicizumab

A

A biospecific antibody that mimics the activity of factor VIII

Used to treat Hemophilia A

27
Q

Rebalancing therapy for Hemophilia patients:

A

Block antithrombin or other anticoagulants (makes the patients hypercoagulable but really normal)

28
Q

Factor XI deficiency:

A

•Autosomal recessive

  • More commonly found in Ashkenazi Jews
  • Variable bleeding manifestations, even within members of the same family
  • Post-surgical bleeding
  • Mucocutaneous bleeding
  • No factor concentrate
  • Treat with plasma

Hematology Block 2 (7 decks)

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