Abnormal activated PTT Flashcards
PTT traditionally has been a good test for monitoring which anticoagulant?
- Heparin
What are common causes of an isolated, abnormal PTT?
- Medications: Heparin, direct Xa inhibitors, and direct thrombin inhibitors
- Coagulation factor deficiency with associated hemorrhage
- Coagulation factor deficiency with no clinical consequences
- Non-specific factor inhibitor (LA)
- Specific factor inhibitory
- Spurious or pre analytic errors
Which factor deficiencies have been associated with bleeding?
- VIII (hemophilia A and vWD)
- IX
- XI
*Note: multiple factor deficiencies as seen in liver disease or consumptive coagulopathy
How is vWD associated with Factor VIII?
- vWF circulates bound to Factor VIII and stabilizes it in circulation
- in vWD therefore there is a reduced level of Factor VIII leading to a prolonged PTT
What is the inheritance pattern of Factor VIII deficiency or Hemophilia A?
- X-linked recessive
- women are carriers but through various ways may rarely also contain the disease
IMP: spontaneous mutations may occur in 30% of cases
What is the most common type of mutation in Hemophilia A and what is the risk associated with it?
- > 100 mutations in Factor VIII
- most common (~50%) are inversions of intron 22 and intron 1
- patients with the inversions or large deletions are at higher risk of developing an inhibitor with replacement therapy
How is Type 2N vWD associated with or mimicking hemophilia A?
- Type 2N vWD is caused by a mutation in the vW molecule impairing its ability to bind to Factor VIII
-mild cases are difficult to differentiate from mild Factor VIII deficiency - Type 2N vWD is inherited in an autosomal recessive manner (different from Hemophilia A)
What is considered a very mild Factor VIII deficiency?
- Factor VIII: >20%
- No spontaneous hemorrhage
- Rare traumatic hemorrhage
What is considered a mild Factor VIII deficiency?
- Factor VIII: 5-20%
- Rare spontaneous hemorrhage
- Common traumatic hemorrhage
What is considered a moderate Factor VIII deficiency?
- Factor VIII: 2-5%
- Unusual spontaneous hemorrhage
- Always traumatic hemorrhage
What is considered a severe Factor VIII deficiency?
- Factor VIII: <2%
- Common spontaneous hemorrhage
- Always traumatic hemorrhage
What is the inheritance pattern of Hemophilia B (Factor IX)?
- X-linked recessive
- less frequent than Factor VIII deficiency
What is Factor XI deficiency also called? How is it inherited?
- Hemophilia C
- Autosomal recessive
- unusually high prevalence in the Ashkenazi Jews
What is the phenotypic manifestation of Factor XI deficiency?
- bleeding is variable
- often mild compared to the level of decrease in factor
What is the treatment for Factor XI deficiency?
- No commercially available factor concentrates
- FFP is used in cases of hemorrhage or prophylaxis
