Question 1

Which of the following is a disorder with absent platelet glycoprotein Ib/IX/V and in which the patient has moderate thrombocytopenia, large platelets, and normal aggregometry with all agents except ristocetin?

A) von Willebrand disorder (VWD)
B) Bernard-Soulier syndrome
C) Glanzmann thrombasthenia
D) Dense granule deficiency

Bernard-Soulier syndrome

Accepted Answer

Absent platelet glycoprotein Ib/IX/V is a feature of Bernard-Soulier syndrome, which presents with moderate thrombocytopenia, large platelets, and abnormal aggregometry with ristocetin, but normal aggregometry with other agents. Von Willebrand disorder (VWD) is characterized by low levels or abnormal function of von Willebrand factor, leading to bleeding symptoms. Glanzmann thrombasthenia is caused by the absence or dysfunction of the platelet glycoprotein IIb/IIIa complex and presents with severe bleeding. Dense granule deficiency is a rare inherited disorder that affects platelet function, resulting in bleeding disorders.

Question 2

Which of the following is normal in a patient regularly taking aspirin? A) Bleeding time B) Platelet cyclooxygenase function C) Synthesis of thromboxane A₂ D) Platelet count

Accepted Answer

Aspirin inhibits platelet cyclooxygenase, affecting thromboxane A2 synthesis and prolonging bleeding time, but it does not affect the platelet count.

Question 3

A 78-year-old patient recently noticed dark blotches on his forearms and on the backs of his hands. He seems to bruise even when a phlebotomy is performed using excellent technique with no problems encountered. No other symptoms exist, and all laboratory tests are normal. Which of the following is the most likely diagnosis?

A) Hereditary hemorrhagic telangiectasia
B) Ehlers-Danlos syndrome
C) Paraproteinemia and amyloidosis
D) Senile purpura

Senile purpura

Accepted Answer

The dark blotches and easy bruising experienced by the patient are classic symptoms of senile purpura, which is a common condition found in the elderly. Hereditary hemorrhagic telangiectasia and Ehlers-Danlos syndrome are both genetic disorders that can cause abnormal bleeding, but they typically present with additional symptoms and lab abnormalities. Paraproteinemia and amyloidosis can also cause bleeding and bruising, but they typically present with additional symptoms and lab abnormalities as well.

Question 4

Which of the following is the most likely diagnosis for a patient with a normal platelet count, prolonged bleeding time, and no aggregation with any agent except ristocetin?&#10;A) Aspirin ingestion&#10;B) Gray platelet syndrome&#10;C) Vitamin C deficiency&#10;D) Glanzmann thrombasthenia

Accepted Answer

Glanzmann thrombasthenia is a rare congenital disorder in which platelets cannot aggregate due to a defect or deficiency in the platelet glycoprotein IIb/IIIa receptor. This results in a prolonged bleeding time, normal platelet count, and no response to most platelet aggregation agents except for ristocetin. Aspirin ingestion would result in a decrease in platelet function and aggregation, but would not specifically affect response to ristocetin. Gray platelet syndrome is a rare inherited platelet disorder characterized by large, gray-colored platelets and a decreased number of platelet alpha-granules. Vitamin C deficiency can lead to bleeding due to weakened blood vessels, but would not specifically result in a lack of response to platelet aggregation agents.

Question 5

All of the following are common conditions or situations that interfere with platelet function except:&#10;A) Liver disease&#10;B) Uremia&#10;C) Allergic purpura&#10;D) Cardiopulmonary bypass surgery

Accepted Answer

Liver disease, uremia, and cardiopulmonary bypass surgery are all known to interfere with platelet function. However, allergic purpura is not a condition that directly affects platelet function. Allergic purpura, also known as Henoch-Schonlein purpura, is a type of blood vessel inflammation that can cause a rash of small purple spots (purpura) on the skin, but it does not directly impact platelet function.

Question 6

What is the mechanism for the platelet dysfunction in multiple myeloma and Waldenstr&#246;m macroglobulinemia?&#10;A) Granules become deficient.&#10;B) Platelets are coated with paraprotein.&#10;C) Nitric oxide is not produced.&#10;D) Cyclooxygenase is acetylated.

Accepted Answer

In multiple myeloma and Waldenström macroglobulinemia, paraproteins (abnormal antibodies) coat the platelets, leading to platelet dysfunction.

Question 7

The qualitative platelet disorders and vascular disorders typically exhibit what type of symptoms?&#10;A) Superficial bleeding&#10;B) Deep tissue bleeding&#10;C) Hemarthrosis&#10;D) Thrombosis

Accepted Answer

Qualitative platelet disorders and vascular disorders often present with superficial bleeding, such as petechiae, purpura, or mucosal bleeding, rather than deep tissue bleeding, hemarthrosis, or thrombosis.

Question 8

Clopidogrel is a drug used therapeutically for patients with a risk of arterial thrombi because it:&#10;A) Inhibits thrombin&#10;B) Activates the protein C pathway&#10;C) Inhibits platelet function&#10;D) Activates plasminogen

Accepted Answer

Clopidogrel inhibits platelet function by irreversibly binding to P2Y12 receptors on platelets, inhibiting ADP-mediated activation of glycoprotein IIb/IIIa and subsequent platelet aggregation.

Question 9

What types of hemostatic complications are found in patients with myeloproliferative disorders?&#10;A) Hemorrhagic&#10;B) Thrombotic&#10;C) Abnormal platelet function&#10;D) All of the above

Accepted Answer

Patients with myeloproliferative disorders can experience both bleeding (hemorrhagic) and clotting (thrombotic) complications due to abnormal platelet function. Therefore, all of the above choices are possible hemostatic complications in these patients.

Question 10

Which of the following is the most common cause of acquired platelet dysfunction?&#10;A) Myeloproliferative disorders&#10;B) Wiskott-Aldrich syndrome&#10;C) Drugs, especially aspirin&#10;D) Afibrinogenemia

Accepted Answer

Platelet dysfunction caused by drugs, especially aspirin, is the most common cause of acquired platelet dysfunction. Aspirin irreversibly inhibits the cyclooxygenase enzyme, leading to decreased production of thromboxane A2 and subsequent impaired platelet activation and aggregation. Other drugs that can cause platelet dysfunction include NSAIDs, clopidogrel, and ticlopidine.

Question 11

Platelet count and function studies are performed on a patient with a history of easy bruising, and the following results are obtained:

What is the most likely diagnosis for this patient?

A) Bernard-Soulier disease
B) Dense granule deficiency
C) Glanzmann thrombasthenia
D) Gray platelet syndrome

Accepted Answer

The answer of Platelet count and function studies are performed...

Question 12

Which of the following is normal in primary dense granule deficiency?&#10;A) Platelet count&#10;B) Bleeding time&#10;C) Platelet aggregometry&#10;D) Platelet morphology

Accepted Answer

The answer of Which of the following is normal in...

Question 13

Which of the following is true regarding testing for the diagnosis of vascular disorders?&#10;A) Most do not have abnormal clinical laboratory tests.&#10;B) The platelet count and aggregometry are useful.&#10;C) The prothrombin time (PT) and partial thromboplastin time (PTT) are most useful.&#10;D) Evaluation of von Willebrand factor (VWF) is useful.

Accepted Answer

The answer of Which of the following is true regarding...

Deck 44: Qualitative Disorders of Platelets and Vasculature