Lecture 30 - Disorders of Primary Hemostasis

Question 1

Disorders of Primary Hemostasis that cause bleeding typically manifest as _______ bleeding, whereas disorders of secondary hemostasis that cause bleeding typically manifest as ____ ____ bleeding.

Answer 1

Mucocutaneous bleeding

Soft Tissue

Question 2

Lab screening tests for Primary hemostasis obviously checks PLT count, blood smear and BM biopsy, but Secondary hemostasis screenings look for coagulation factor deficiencies.

PT tests extrinsic and common pathways, so it covers factors: __, __, __, __, and __.

APTT tests intrinsic and common pathways, so it covers factors: __, __, __, __, __, __, __, __, PK, HK.

TCT pf Fibrinogen assay tests factor: __ (fibrinogen is this factor.)

Answer 2

I, II, V, VII, X

I, II, V, VIII, IX, X, XI, XII, PK, HK

I

Question 3

Thrombocytopenia is considered a disorder of _____ hemostasis (should make sense given that it means low platelet count) and is defined as PLT < ______/uL. However, risk of bleeding increases when PLT < ______/uL and severe risk when PLT < ______/uL

Answer 3

Primary

100,000/uL

20,000

10,000

Question 4

Immune Thrombocytopenic Purpura (ITP) is an autoimmune disease in which patients produce auto-Abs against antigens on _____ and the cells that create them, _______. Be on the lookout for low PLT count on blood test with all else normal.

There is an Acute and Chronic form. Which one occurs in children and typically does not require treatment?

Answer 4

Platelets

Megakaryocytes

Acute is typically seen in children after viral infection or Immunization and typically resolves without treatment.

Question 5

Heparin-Induced Thrombocytopenia (HIT II) occurs in 1-5% of patients receiving unfractionated Heparin. Heparin binds Factor ___ on platelet membranes, and patients develop Ig___ to this complex. This disorder typically manifests as a venous _____ rather than bleeding, because the immune complexes that form can activate platelets and induce this.

Answer 5

Factor IV

IgG

Thrombosis

Question 6

Thrombotic Thrombocytopenia Purpura (TTP) is a MAHA that can be acquired or familial, but in both cases _______13 is affected (gene mutation in familial or auto-AB against the protein in acquired). Remember this protein is necessary for cleavage of ___ ____ Factor –> if it is not cleaved as it is secreted from _____ cells in the microvasculature, it cannot fold properly, leaving platelet binding sites exposed –> this leads to thrombi formation.

Answer 6

ADAMTS13

Von Wildebrand Factor

Endothelial cells

Question 7

What is the triad of symptoms for TTP? Remember that blood smear will show ______ (spherocytes or schistocytes?), and coagulation tests are NORMAL.

Answer 7

The triad includes Thrombocytopenia, microangiopathic hemolytic anemia, and neurological symptoms.

Schistocytes

Question 8

Hemolytic Uremic Syndrome (HUS) is a MAHA that is observed in ______ (children or adults?). This disease is caused by _____-toxin producing __ ____ (STEC). The toxin damages endothelial cells of the _____, causing release of ULVWF. Patients will present with acute gastroenteritis, bloody _____, bruising, and epistaxis.

Answer 8

Children

Shiga-toxin producing E. coli (STEC)

Kidney

Bloody diarrhea

Question 9

HUS also has a triad of symptoms which includes ________, microangiopathic hemolytic anemia, and _____ failure (remember this last one is neurological disorders in TTP).

Answer 9

Thrombocytopenia

Renal failure

Question 10

Disseminated Intravascular Coagulation (DIC) affects BOTH platelets and coagulation factors. Look for ___-dimers which are the product of plasmin cleaving cross-linked fibrin.

Answer 10

D-dimers

Question 11

Functional platelet disorders show basically ______ (normal, elevated, or depressed?) platelet counts and coag factors. Most are acquired, but some can be inherited –> Bernard Soulier Sndrome (BSS) is an example, and is caused by an _____ defect (mutation in gene for GP Ib-IX-V receptor). Look for _____ platelets on blood smear.

Answer 11

Normal

Adhesion

Giant platelets

Question 12

_______ Thrombasthenia is an aggregation defect (mutation in GP IIb-IIIa receptor) and presents as severe ________ bleeding in neonate/infant.

Answer 12

Glanzmann Thrombasthenia

Mucocutaneous bleeding

Question 13

Von Willebrand Factor disease is the most common congenital bleeding disorder and is passed on via autosomal _______ inheritance. Remember that VWF binds Factor _____, extending its half-life, so if VWF is deficient or defective, this factor will be decreased. Which coag test would show this, PT, APTT, or TCT?

Answer 13

Dominant

Factor VIII

APTT

Question 14

_______ increases release of VWF from endothelial cells.

Answer 14

Desmopressin