Question 1

Immune complexes induce vasculitis by which of the following processes?

Accepted Answer

Immune complexes induce vasculitis primarily through the recruitment of neutrophils to the site where the immune complexes are deposited. These neutrophils, in an attempt to phagocytize the immune complexes, release enzymes and free oxygen radicals, which cause damage to the vessel wall, leading to vasculitis.

Question 2

What would be the expected laboratory results in a patient with thrombocytopenia?

Accepted Answer

Thrombocytopenia is defined as a platelet count <150 × 10⁹/L, and severe thrombocytopenia is defined as a platelet count <50 × 10⁹/L. Therefore, a patient with thrombocytopenia would be expected to have platelet counts <50 × 10⁹/L.

Answer: B
 Bleeding time is a measure of platelet function, rather than platelet count. It is often normal in patients with thrombocytopenia, as they may have enough functional platelets to prevent bleeding.

Answer: C
 Thrombocytopenia does not affect the clotting factors, so PT and APTT would be normal or near-normal in these patients.

Answer: D
 Fibrinogen is not directly affected by thrombocytopenia, so it would be expected to be normal in these patients.

Question 3

Which of the following characteristics of chronic ITP differentiates it from acute ITP?

Accepted Answer

Chronic ITP is more common in females with a gender predilection of 3:1, whereas acute ITP does not have this gender bias.

Question 4

What laboratory tests are used to assess disorders of primary hemostasis and secondary hemostasis?

Accepted Answer

The answer of What laboratory tests are used to assess...

Question 5

Give at least five markers of differentiation between acute and chronic ITP.

Accepted Answer

The answer of Give at least five markers of differentiation...

Question 6

Describe the following,and indicate whether they are typically seen in disorders of primary or secondary hemostasis.
a.Petechiae
b.Purpura
c.Ecchymoses
d.Hematomas

Accepted Answer

The answer of Describe the following,and indicate whether they are...

Question 7

How do hematologic disorders contribute to the pathogenesis of thrombocytopenia?

Accepted Answer

The answer of How do hematologic disorders contribute to the...

Question 8

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

Accepted Answer

The answer of Explain the pathophysiology of the following and...

Question 9

What is the most common cause of thrombocytopenia?

Accepted Answer

Increased destruction is the most common cause of thrombocytopenia, which can occur in conditions such as immune thrombocytopenic purpura (ITP), drug-induced thrombocytopenia, and thrombotic microangiopathies.

Question 10

A patient has a splitting headache shortly before getting her blood tested.She takes a couple of aspirin and is scheduled for platelet aggregation studies.What effect will this have on the platelet aggregation studies?

Accepted Answer

Aspirin is a platelet inhibitor and it works by irreversibly inhibiting the enzyme cyclooxygenase which is responsible for the production of thromboxane A2, a potent platelet aggregator. Therefore, when a patient takes aspirin before platelet aggregation studies, the platelets will show diminished activity with selected agonists. This is because aspirin inhibits thromboxane A2 production, which is required for platelet aggregation. However, it should be noted that aspirin may not affect all agonists equally and some types of platelet aggregation studies may be less affected by aspirin than others.

Question 11

Aspirin affects platelet aggregation because it interferes with:

Accepted Answer

Aspirin works by inhibiting the activity of cyclooxygenase (COX) enzymes, which are responsible for producing prostaglandins that promote platelet aggregation. By inhibiting COX, aspirin reduces the formation of these prostaglandins and therefore inhibits platelet aggregation. Choices B, C, and D are not directly affected by aspirin.

Question 12

A patient is known to be a chronic alcoholic.His blood is drawn,and his platelet count is 72 x 10⁹/L.What is the most likely reason for this occurrence?

Accepted Answer

Chronic alcohol consumption can lead to bone marrow suppression, resulting in acquired hypoplasia and decreased platelet production.

Question 13

Splenomegaly can cause thrombocytopenia by which of the following mechanisms?

Accepted Answer

Splenomegaly can cause thrombocytopenia primarily through platelet sequestration. The enlarged spleen can hold onto more platelets than normal, reducing the number of platelets in circulation.

Question 14

Which of the following contributes to the pathogenesis of Bernard-Soulier syndrome?

Accepted Answer

Bernard-Soulier syndrome is a rare inherited bleeding disorder characterized by a deficiency or dysfunction of glycoprotein Ib/IX complex, which is essential for platelet adhesion to von Willebrand factor and subsequently to collagen. Abnormalities in glycoprotein IIb/IIIa are associated with another bleeding disorder, Glanzmann thrombasthenia. High platelet count is seen in reactive thrombocytosis and low fibrinogen level is associated with fibrinogen deficiency or afibrinogenemia.

Question 15

What is a common etiology of ITP in children?

Accepted Answer

Chickenpox is a common trigger for immune thrombocytopenic purpura (ITP) in children. ITP is an autoimmune disorder characterized by a low platelet count resulting in abnormal bleeding and bruising. Other common triggers include viral infections, vaccinations, and medications.

Quiz 33: Disorders of Primary Hemostasis