Interpret the following results: PT: 11.8 sec (RR: 11.2-13.8 ...

[panfilo]

Interpret the following results:
 
  PT: 11.8 sec (RR: 11.2-13.8 sec)
  INR: 1.07
  APTT: 57 sec (RR: 23-32 sec)
  BT: 12 min
  Ristocetin aggregation: decreased aggregation
 
  Based on this information, from what is the patient most likely suffering?
  a. Hemophilia A
  b. Bernard-Soulier syndrome
  c. DIC
  d. von Willebrand's disease

Question 2

Explain the pathophysiology of the following and why each typically has normal coagulation screening tests.
 
  a. Bernard-Soulier syndrome
  b. Glanzmann's thrombasthenia
  c. -storage pool disease
  d. Gray platelet syndrome
 
  What will be an ideal response?

[wshriver]

Answer to Question 1

Correct Answer: D

Answer to Question 2

Answer regarding pathophysiology: Bernard-Soulier syndrome: defect in glycoprotein Ib/IX
Glanzmann's thrombasthenia: defect in glycoprotein IIb/IIIa
-Storage pool disease: defect in dense granules
Gray platelet syndrome: defect in alpha granules
All four of these disorders are inherited qualitative platelet defects. All have defects in platelet function, not in the synthesis of coagulation factors and/or serine proteases. That is why the clot-based coagulation screening tests are typically normal. They all have prolonged bleeding time because the bleeding time assesses platelet function in vivo and have abnormal platelet aggregation studies.