Ch4 - 3) Other disorders of Hemostasis Flashcards
What is Heparin induced thrombocytopenia?
Platelet destruction that arises secondary to heparin therapy
How does Heparin induced thrombocytopenia lead to thrombosis?
Fragments of destroyed platelets may activate remaining platelets, leading to thrombosis
What is disseminated intravascular coagulation?
Pathologic activation of the coagulation cascade
What does disseminated intravascular coagulation result in?
- Widespread microthrombi result in ischemia and infarction, 2. Consumption of platelets and factors results in bleeding, especially from IV sites and mucosal surfaces (bleeding from body orifices).
Is disseminated intravascular coagulation usually primary or secondary?
Almost always secondary to another disease process
What are some situations that may result in disseminated intravascular coagulation?
Obstetric complications, sepsis, adenocarcinoma, Acute promyelocytic leukemia, Rattlesnake bite
Obstetric complications and disseminated intravascular coagulation
Tissue thromboplastin in the amniotic fluid activates coagulation
Sepsis and disseminated intravascular coagulation
(especially with E. coli or Neisseria meningitidis) ? Endotoxins from the bacterial wall and cytokines (e.g TNF and IL-1) induce endothelial cells to make tissue factor.
Adenocarcinoma and disseminated intravascular coagulation
Mucin activates coagulation.
Acute promyelocytic leukemia and disseminated intravascular coagulation
Primary granules activate coagulation.
Rattlesnake bite and and disseminated intravascular coagulation
Venom activates coagulation
Laboratory findings for disseminated intravascular coagulation include?
decreased platelet count, increased PT/PTT, decreased fibrinogen, Microangiopathic hemolytic anemia, Elevated fibrin split products, particularly D-dimer
What is the best screening test for DIC?
Elevated D-dimer
D dimer is derived from?
splitting of cross-linked fibrin; D-dimer is not produced from splitting of fibrinogen.
Treatment of DIC involves?
addressing the underlying cause and transfusing blood products and cryoprecipitate (comains coagulation factors), as necessary.
What does normal fibrinolysis do?
Normal fibrinolysis removes thrombus after damaged vessel heals
Tissue plasminogen activator (tPA)
converts plasminogen to plasmin
Plasmin
cleaves fibrin and serum fibrinogen, destroys coagulation factors, and blocks platelet aggregation.
a2-antiplasmin
inactivates plasmin.
What are the disorders of fibrinolysis due to? What does this result in?
plasmin overactivity resulting in excessive cleavage of serum fibrinogen.
What are some examples of disorders of fibrinolysis?
radical prostatectomy, cirrohsis of the liver
How does radical prostatectomy lead to a disorder of fibrinolysis?
Release of urokinase activates plasmin
How does cirrhosis of the liver lead to a disorder of fibrinolysis?
reduced production of a2-antiplasmin
How does disorders of fibrinolysis present?
with increased bleeding (resembles DIC)
Laboratory findings for disorders of fibrinolysis include
Increased PT/PTT, increased bleeding time with normal platelet count, Increased fibrinogen split products without D-dimers
Why is there increased fibrinogen split products without D-dimers in disorders of fibrinolysis?
Serum fibrinogen is lysed; however, D-dimers are not formed because fibrin thrombi are absent
Why is there increased bleeding time with disorders of fibrinolysis?
Plasmin blocks platelet aggregation
Why is there increased PT/PTT with disorders of fibrinolysis?
Plasmin destroys coagulation factors.
What is the treatment for disorders of fibrinolysis?
it is aminocaproic acid, which blocks activation of plasminogen.
