OnlineMedEd: Hematology Oncology - "Bleeding"

Question 1

Primary hemostasis starts with _____________.

Answer 1

von Willebrand factor binding to glycoprotein Ib in the ECM behind damaged endothelium; this whole step is called adhesion

Question 2

What two mediators are important in the activation step of hemostasis (the second step)?

Answer 2

• Thromboxane A2

* ADP

Question 3

What drugs target the aggregation step of platelet activation?

Answer 3

• Abciximab
• Eptifibatide
• Tirofiban

These three drugs inhibit the GPIIb/IIIa connective protein.

Question 4

Factor I and Ia are also called ____________, respectively.

Answer 4

fibrinogen and fibrin

Question 5

___________ converts plasminogen to plasmin.

Answer 5

Tissue plasminogen activator (tPA)

Question 6

Describe the types of bleeding seen in disorders of primary and secondary hemostasis.

Answer 6

• Primary: superficial (gums, vagina, skin)

* Secondary: deep (joint, hematoma)

Question 7

Review the workup of bleeding.

Answer 7

• First, you should (officially) draw labs based on type of bleeding: for petechiae, gingival, or vaginal bleeding, do a CBC for platelet count; for hemarthrosis or hematomas, do a PT/PTT. (In reality, you’ll do both at the same time.)
• Second, for platelet bleeding, look at the number of platelets. If it is low, then it is thrombocytopenia. If it is not low, then the disorder is likely one of platelet function: iatrogenic, uremia, or vWF deficiency.
• Second, for factor bleeding, look at the PT/PTT. If those are elevated, then get a mixing study to rule out inhibition (antiphospholipid antibody).

Question 8

Review the three categories of cause of thrombocytopenia.

Answer 8

• Destruction: ITP, TTP, HUS, DIC
• Production: aplastic anemia, malignancy, myelodysplastic syndrome
• Sequestration: cirrhosis,

Question 9

Diagnose vWF with ________________.

Answer 9

first, a CBC showing normal platelet count, and second, a vWF antigen assay

Question 10

Hereditary platelet disorders include von Willebrand factor deficiency, ____________, and ____________.

Answer 10

Bernard-Soulier (GPIb); Glanzman thrombasthenia (GPIIb/IIIa)

Question 11

Elevated PT/PTT that corrects with mixing could be what possible diseases?

Answer 11

• Factor deficiency
• Iatrogenic (warfarin, rivaroxaban, epixaban, dabigatran, bivalirudin)
• Vitamin K deficiency
• DIC
• vWF with VIII deficiency