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

Patients with Bernard-Soulier syndrome have deficient glycoprotein Ib/IX/V receptors on their surface.This is inherited as an autosomal recessive disorder;heterozygotes are normal or near normal,but homozygotes have (usually)a low platelet count and enlarged platelets.Aggregation is normal with all agonists except ristocetin.

Question 2

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

Clinical laboratory tests are not available for evaluation and diagnosis of vascular disorders.Ruling out other sources of bleeding disorders often makes the diagnosis.The usual clinical signs are easy bruising and spontaneous bleeding,especially from mucosal surfaces.In that respect they are similar to platelet dysfunction disorders.

Question 3

Which of the following is normal in a patient regularly taking aspirin?&#10;A)platelet aggregation&#10;B)platelet cyclooxygenase function&#10;C)synthesis of thromboxane A2&#10;D)platelet count

Accepted Answer

Only the platelet count,of those evaluations listed,is normal in a patient who regularly takes aspirin.Aspirin acetylates cyclooxygenase,which is necessary for the synthesis of thromboxane A₂.

Question 4

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

Aspirin and other drugs are the most common causes of acquired platelet dysfunction.

Question 5

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 both of these disorders,a high concentration of a monoclonal protein is present in circulation.This is called a paraprotein,and it can coat platelets,interfering with surface receptors,leading to their dysfunction.

Question 6

Which of the following is the most likely diagnosis for a patient with a normal platelet count 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

Patients with Glanzmann thrombasthenia have a normal platelet count and prolonged bleeding time.Their platelets do not aggregate with any agonist except ristocetin.

Question 7

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 one of the chronic myeloproliferative disorders,such as polycythemia vera and essential thrombocythemia,may have abnormal platelet function;clinically,they may result in either abnormal bleeding or abnormal thrombosis.Some patients develop both,although this is rare.

Question 8

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

Allergic purpura does not interfere with platelet function.All of the other listed conditions or situations can affect platelet function.

Question 9

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

Accepted Answer

Senile purpura is the most likely diagnosis for this 78-year-old man who only recently began to notice abnormal bruising and/or bleeding.The hereditary abnormalities would have presented earlier in life.Paraproteinemia and amyloidosis would demonstrate other abnormal clinical laboratory testing.

Question 10

Clopidogrel (Plavix)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 is an antiplatelet function drug used for three reasons: (1)to treat patients with arterial occlusive disease;(2)for prevention of myocardial infarction;and (3)to decrease the risk of thrombotic stroke in patients with cerebrovascular disease and in patients who are intolerant of aspirin.

Question 11

Platelet count and function studies are performed on a patient with a history of easy bruising,and the following results are obtained:
$\begin{array}{ll}\underline { \text { Test }}&\underline { \text { Result }}\\\text { Platelet count } & 295 \times 10^{9} / \mathrm{L} \\\text { Platelet function assay } & \text { Prolonged } \\\text { Platelet aggregation with epinephrine } & \text { Primary but no secondary wave } \\\text { Platelet aggregation with low-dose adenosine } & \text { Primary but no secondary wave }\\\text { diphosphate (ADP) }\\\text { Platelet agoregation with ristocetin }& \text { Normal }\\\end{array}$
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

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

The answer of The qualitative platelet disorders and vascular disorders...

Deck 41: Qualitative Disorders of Platelets and Vasculature