Platelets: Qualitative and Quantitative Disorders Flashcards
3 functions of von Willebrand Factor (vWF)
- Carrier protein for Factor VIII (VIII:C)
- Participates in platelet’s adhesion to subendothelial collagen
- Facilitates a normal aggregation response to ristocetin
von Willebrand disease
- Pathogenesis
Clinical disorder due to deficiency of vWF
von Willebrand disease
- Bleeding time results
Increased
von Willebrand disease
- Closure time results (PFA)
Increased
von Willebrand disease
- Platelet adhesion result
Abnormal
von Willebrand disease
- Platelet aggregation w/ ristocetin
Abnormal ristocetin induced aggregation
von Willebrand disease
- Platelet count
Can be normal or abnormal → not a hallmark
von Willebrand disease
- APTT result
Prolonged due to ↓ VIII:C
Bernard-Soulier syndrome
- Pathogenesis
Missing GPIb/IX receptor complex
- Platelets cannot adhere to subendothelium via vWF
Bernard-Soulier syndrome
- Bleeding time result
Prolonged
Bernard-Soulier syndrome
- Platelet aggregation w/ ADP and ristocetin
- ADP: normal
- Ristocetin: abnormal
Bernard-Soulier syndrome
- Platelet adhesion result
Abnormal
Bernard-Soulier syndrome
- Platelet count
Decreased
Bernard-Soulier syndrome
- Platelet morphology
Giant platelets
Glanzmann’s thrombasthenia
- Pathogenesis
Missing GPIIb/IIIa receptor complex
- Platelets cannot bind to fibrinogen and bridge/attach to one another → cannot aggregate
Glanzmann’s thrombasthenia
- Bleeding time result
Prolonged
Glanzmann’s thrombasthenia
- Platelet adhesion result
Normal
Glanzmann’s thrombasthenia
- Platelet aggregation w/ ADP and ristocetin
- ADP: abnormal
- Ristocetin: normal
Glanzmann’s thrombasthenia
- Platelet count
Normal
Glanzmann’s thrombasthenia
- Platelet morphology
Normal
5 acquired qualitative platelet disorders
- Drug therapy (most common cause)
- Renal disease (uremia)
- Dysproteinemias
- Liver disease
- Platelet Abs
4 general causes for thrombocytopenia
- ↓ platelet production
- Ineffective thrombopoiesis
- Abnormal distribution of platelets
- ↑ destruction of platelets