Welcome to Part 39 of our Free ASCP MLS Exam Practice Questions series. This section focuses on Platelet Disorders, including both quantitative abnormalities (thrombocytopenia, thrombocytosis) and functional platelet defects.
Platelet disorders are crucial for MLS exam preparation because they play a central role in hemostasis and bleeding disorders. A solid understanding of their physiology, pathology, and laboratory evaluation is essential.
🔹 Topics Covered in This Part
- Platelet production and normal physiology
- Thrombocytopenia (immune, non-immune, drug-induced, hereditary)
- Thrombocytosis and related myeloproliferative conditions
- Functional platelet defects (e.g., Glanzmann thrombasthenia, Bernard–Soulier syndrome)
- Acquired platelet dysfunctions (uremia, medications)
- Laboratory evaluation: platelet counts, aggregation studies, bleeding time, PFA-100
60 MCQs (3281-3340):
📘 How to Use These Practice Questions
- The questions in this section emphasize the diagnosis, clinical features, and lab findings in platelet disorders.
- Numbering continues from the previous set — starting at Question 3281.
- Answer keys with explanations will be included at the end to support concept reinforcement.
- The normal platelet count reference range in adults is:
a) 50–100 × 10⁹/L
b) 100–150 × 10⁹/L
c) 150–450 × 10⁹/L
d) 450–600 × 10⁹/L - A platelet count below 150 × 10⁹/L is defined as:
a) Thrombocytopenia
b) Thrombocytosis
c) Pancytopenia
d) Leukocytosis - Which of the following is a common cause of thrombocytopenia?
a) Iron deficiency anemia
b) Immune destruction of platelets
c) Vitamin B12 deficiency
d) Erythropoietin deficiency - A significantly elevated platelet count above 600 × 10⁹/L is called:
a) Reactive thrombocytosis
b) Essential thrombocythemia
c) Polycythemia
d) Pancytopenia - Q394. Which test is most useful to evaluate platelet function
a) PT
b) aPTT
c) Platelet aggregation studies
d) Serum ferritin - Bernard–Soulier syndrome is caused by a deficiency of:
a) GPIb receptor
b) GPIIb/IIIa receptor
c) Factor VIII
d) vWF - Glanzmann thrombasthenia is due to defective:
a) GPIb receptor
b) GPIIb/IIIa receptor
c) ADAMTS13 deficiency
d) Collagen binding - Which inherited disorder is associated with giant platelets and defective adhesion?
a) Glanzmann thrombasthenia
b) Bernard–Soulier syndrome
c) Wiskott–Aldrich syndrome
d) Gray platelet syndrome - The bleeding time test primarily evaluates:
a) Coagulation factor deficiencies
b) Platelet function
c) Fibrinolysis
d) Clot stability - Which of the following drugs irreversibly inhibits platelet function?
a) Warfarin
b) Heparin
c) Aspirin
d) Streptokinase - Platelet satellitism is an in-vitro phenomenon associated with:
a) EDTA anticoagulant
b) Heparin therapy
c) Vitamin K deficiency
d) Thrombocytopenia - A patient with microangiopathic hemolytic anemia, thrombocytopenia, and renal failure most likely has:
a) Hemophilia A
b) Disseminated intravascular coagulation
c) Thrombotic thrombocytopenic purpura (TTP)
d) Von Willebrand disease - TTP is associated with a deficiency of:
a) Factor VIII
b) ADAMTS13
c) Fibrinogen
d) Thrombin - Which condition is caused by autoimmune platelet destruction?
a) Hemophilia
b) ITP (Immune thrombocytopenic purpura)
c) TTP
d) Polycythemia vera - Which laboratory finding is typical of ITP?
a) Normal PT and aPTT, isolated thrombocytopenia
b) Prolonged PT, prolonged aPTT
c) Pancytopenia
d) Increased fibrin degradation products - Gray platelet syndrome is associated with a deficiency of:
a) Dense granules
b) Alpha granules
c) Lysosomal enzymes
d) GPIb receptor - Which platelet disorder often presents with eczema, recurrent infections, and thrombocytopenia?
a) Bernard–Soulier syndrome
b) Glanzmann thrombasthenia
c) Wiskott–Aldrich syndrome
d) Essential thrombocythemia - Which finding is most consistent with heparin-induced thrombocytopenia (HIT)?
a) Increased platelet count
b) Thrombocytopenia with thrombosis
c) Prolonged bleeding time only
d) Increased fibrinogen - Pseudothrombocytopenia can result from:
a) Automated analyzer error due to clumping
b) Bone marrow failure
c) Splenomegaly
d) Increased platelet destruction - Which of the following is NOT a cause of thrombocytopenia?
a) Splenic sequestration
b) Decreased marrow production
c) Increased destruction
d) Increased fibrinogen - The most common clinical symptom of platelet disorders is:
a) Deep muscle bleeding
b) Joint bleeding
c) Petechiae and mucosal bleeding
d) Retroperitoneal hemorrhage - A laboratory finding of thrombocytosis is most commonly secondary to:
a) Infection or inflammation
b) G6PD deficiency
c) Vitamin B12 deficiency
d) Sickle cell disease - Which of the following platelet function tests is prolonged in aspirin therapy?
a) PT
b) aPTT
c) Bleeding time
d) Serum ferritin - Which is a distinguishing feature of platelet disorders versus coagulation factor deficiencies?
a) Delayed deep tissue bleeding
b) Petechiae and mucosal bleeding
c) Hemarthrosis
d) Retroperitoneal hematoma - May-Hegglin anomaly is associated with:
a) Microcytic anemia
b) Giant platelets and Döhle-like inclusions
c) Hemolysis
d) Hypersegmented neutrophils - The most likely platelet count in a patient with aplastic anemia is:
a) Increased
b) Normal
c) Decreased
d) Variable - Platelet aggregation in response to ristocetin requires:
a) GPIIb/IIIa
b) GPIb and vWF
c) ADP receptor
d) Collagen - Which platelet abnormality is commonly acquired rather than inherited?
a) Glanzmann thrombasthenia
b) Bernard–Soulier syndrome
c) Aspirin-induced platelet dysfunction
d) Wiskott–Aldrich syndrome - Which of the following platelet indices measures average platelet size?
a) MPV
b) MCV
c) PDW
d) RDW - Which type of bleeding is most common in thrombocytopenia?
a) Hemarthrosis
b) Petechiae and epistaxis
c) Deep muscle hematomas
d) Intracranial hemorrhage - What is the typical life span of a platelet in the peripheral blood?
a) 5 days
b) 10 days
c) 20 days
d) 30 days - Aspirin affects platelet function by interfering with the metabolism of which enzyme?
a) Thromboxane synthase
b) Phospholipase A2
c) Cyclooxygenase
d) ADP receptor - In patients with bleeding disorders caused by platelets, the most common type of bleeding is:
a) Hemarthrosis
b) Delayed bleeding
c) Deep hematomas
d) Mucosal bleeding - Which of the following anticoagulants is a direct antiplatelet agent?
a) Argatroban
b) Hirudin
c) Tirofiban
d) Dabigatran - The drugs ticlopidine and clopidogrel inhibit platelet function by which mechanism?
a) Binding von Willebrand factor
b) Inhibiting ADP-mediated platelet aggregation
c) Blocking the GPIIb/IIIa receptor
d) Depleting platelet alpha granule content - Von Willebrand factor mediates platelet adhesion by binding to which platelet receptor?
a) GPIIb/IIIa
b) GPIb/IX/V
c) GPIa/IIa
d) GPIV - Which of the following disease states presents with a quantitative platelet disorder?
a) Von Willebrand disease
b) Hemophilia A
c) Glanzmann thrombasthenia
d) May-Hegglin anomaly - Which statement is associated with acute Idiopathic Thrombocytopenic Purpura (ITP)?
a) It is found primarily in adults
b) Spontaneous remission usually occurs within several weeks
c) Women are more commonly affected
d) Peripheral destruction of platelets is decreased - What is the most common cause of bleeding in patients?
a) Qualitative platelet defect
b) Qualitative abnormality of fibrinogen
c) Quantitative abnormality of fibrinogen
d) Quantitative abnormality of platelets (thrombocytopenia) - A patient develops oozing from a surgical wound post-operation. Lab results show normal PT/aPTT and fibrinogen, but a platelet count of 40 x 10³/µL. The most likely cause is:
a) Dilution of coagulation factors
b) Intravascular coagulation
c) Hypofibrinogenemia
d) Dilutional thrombocytopenia - ADAMTS13 deficiency is responsible for the thrombocytopenia found in:
a) Thrombotic Thrombocytopenic Purpura (TTP)
b) Disseminated Intravascular Coagulation (DIC)
c) Hemolytic Uremic Syndrome (HUS)
d) Idiopathic Thrombocytopenic Purpura (ITP) - In Heparin-Induced Thrombocytopenia (HIT), antibodies are produced against which complex?
a) Anticardiolipin (ACLA)
b) Platelet Factor 4 (PF4)
c) Antithrombin (AT)
d) Beta-2-glycoprotein 1 (B2GP1) - In Polycythemia Vera, the platelet count is typically:
a) Elevated
b) Normal
c) Decreased
d) Variable - A patient presents with a painful knee, slightly enlarged spleen, and a platelet count of 900 x 10³/µL with giant, bizarre-shaped platelets. This is most compatible with:
a) Congenital spherocytosis
b) Rheumatoid arthritis with reactive thrombocytosis
c) Myelofibrosis
d) Idiopathic thrombocythemia (Essential thrombocythemia) - Large blue cytoplasmic inclusions in white blood cells are found in patients with:
a) Wiskott-Aldrich syndrome
b) May-Hegglin Anomaly
c) Ehlers-Danlos syndrome
d) Hermansky-Pudlak syndrome - Von Willebrand factor antigen is synthesized in which of the following cells?
a) Myeloblasts
b) Monoblasts
c) Lymphoblasts
d) Megakaryocytes - Which of the following is a characteristic of platelet-type bleeding?
a) Hemarthrosis
b) Deep muscle hematomas
c) Petechiae and mucosal bleeding
d) Delayed bleeding after trauma - Glanzmann thrombasthenia is characterized by a defect in which platelet receptor?
a) GPIb/IX/V
b) GPIIb/IIIa
c) GPIa/IIa
d) GPIV - Bernard-Soulier syndrome is characterized by a defect in which platelet receptor?
a) GPIb/IX/V
b) GPIIb/IIIa
c) GPIa/IIa
d) GPIV - The bleeding time is most prolonged in which of the following conditions?
a) Hemophilia A
b) Vitamin K deficiency
c) Severe von Willebrand disease
d) Mild factor XI deficiency - A patient with a very low platelet count and normal coagulation studies most likely has:
a) Disseminated Intravascular Coagulation (DIC)
b) Vitamin K deficiency
c) Idiopathic Thrombocytopenic Purpura (ITP)
d) Liver disease - Which of the following disorders is characterized by a normal platelet count but defective platelet function?
a) Idiopathic Thrombocytopenic Purpura (ITP)
b) Thrombotic Thrombocytopenic Purpura (TTP)
c) Glanzmann thrombasthenia
d) May-Hegglin anomaly - Storage pool disease refers to a deficiency of constituents in which platelet organelles?
a) Dense granules
b) Mitochondria
c) Lysosomes
d) Glycogen granules - The platelet count is falsely low on an automated analyzer, but the peripheral smear shows adequate platelets. The most likely explanation is:
a) Platelet satellitism
b) Giant platelets
c) Microcytic red blood cells
d) Cryoglobulinemia - Which of the following is a feature of immune thrombocytopenia?
a) Increased megakaryocytes in the bone marrow
b) Decreased platelet production
c) Splenic atrophy
d) Prolonged PT and aPTT - A patient presents with thrombocytopenia, neurological symptoms, and microangiopathic hemolytic anemia. The most likely diagnosis is:
a) Idiopathic Thrombocytopenic Purpura (ITP)
b) Hemolytic Uremic Syndrome (HUS)
c) Thrombotic Thrombocytopenic Purpura (TTP)
d) Heparin-Induced Thrombocytopenia (HIT) - Which of the following is associated with thrombocytopenia and albinism?
a) Wiskott-Aldrich syndrome
b) May-Hegglin Anomaly
c) Hermansky-Pudlak syndrome
d) Chédiak-Higashi syndrome - The mechanism of action of the antiplatelet drug abciximab is:
a) ADP receptor antagonism
b) GPIIb/IIIa receptor blockade
c) Cyclooxygenase inhibition
d) Phosphodiesterase inhibition - In a patient with uremia, the bleeding tendency is primarily due to:
a) Thrombocytopenia
b) Qualitative platelet defect
c) Factor VIII deficiencyd) Hyperfibrinolysis - Which of the following conditions is characterized by thrombocytopenia, eczema, and immunodeficiency?
a) Wiskott-Aldrich syndrome
b) May-Hegglin Anomaly
c) Hermansky-Pudlak syndrome
d) Scott syndrome
📌 How to Use This Practice Set
- Answer each question before checking the key.
- Focus on why the correct answer is right and the others are wrong.
- Use this set as timed practice to simulate the real exam environment.
Answer Key
Answer Key:
- c) 150–450 × 10⁹/L
- a) Thrombocytopenia
- b) Immune destruction of platelets
- b) Essential thrombocythemia
- c) Platelet aggregation studies
- a) GPIb receptor
- b) GPIIb/IIIa receptor
- b) Bernard–Soulier syndrome
- b) Platelet function
- c) Aspirin
- a) EDTA anticoagulant
- c) Thrombotic thrombocytopenic purpura (TTP)
- b) ADAMTS13
- b) ITP (Immune thrombocytopenic purpura)
- a) Normal PT and aPTT, isolated thrombocytopenia
- b) Alpha granules
- c) Wiskott–Aldrich syndrome
- b) Thrombocytopenia with thrombosis
- a) Automated analyzer error due to clumping
- d) Increased fibrinogen
- c) Petechiae and mucosal bleeding
- a) Infection or inflammation
- c) Bleeding time
- b) Petechiae and mucosal bleeding
- b) Giant platelets and Döhle-like inclusions
- c) Decreased
- b) GPIb and vWF
- c) Aspirin-induced platelet dysfunction
- a) MPV
- b) Petechiae and epistaxis
- b) 10 days
- c) Cyclooxygenase
- d) Mucosal bleeding
- c) Tirofiban
- b) Inhibiting ADP-mediated platelet aggregation
- b) GPIb/IX/V
- d) May-Hegglin anomaly
- b) Spontaneous remission usually occurs within several weeks
- d) Quantitative abnormality of platelets (thrombocytopenia)
- d) Dilutional thrombocytopenia
- a) Thrombotic Thrombocytopenic Purpura (TTP)
- b) Platelet Factor 4 (PF4)
- a) Elevated
- d) Idiopathic thrombocythemia (Essential thrombocythemia)
- b) May-Hegglin Anomaly
- d) Megakaryocytes
- c) Petechiae and mucosal bleeding
- b) GPIIb/IIIa
- a) GPIb/IX/V
- c) Severe von Willebrand disease
- c) Idiopathic Thrombocytopenic Purpura (ITP)
- c) Glanzmann thrombasthenia
- a) Dense granules
- a) Platelet satellitism
- a) Increased megakaryocytes in the bone marrow
- c) Thrombotic Thrombocytopenic Purpura (TTP)
- c) Hermansky-Pudlak syndrome
- b) GPIIb/IIIa receptor blockade
- b) Qualitative platelet defect
- a) Wiskott-Aldrich syndrome
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Top 8 Medical Laboratory Scientist (MLS) Exams that are recognized globally and can help professionals validate their credentials and enhance their career opportunities:
1. ASCP – American Society for Clinical Pathology (USA)
- Exam Name: MLS(ASCP)
- Eligibility: Bachelor’s degree with clinical laboratory experience.
- Global Recognition: High
- Purpose: Certifies Medical Laboratory Scientists in the United States and internationally.
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- Exam Name: MLT(AMT) or MT(AMT)
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4. CSMLS – Canadian Society for Medical Laboratory Science
- Exam Name: CSMLS General or Subject-specific Exams
- Eligibility: Graduation from a CSMLS-accredited program or equivalent.
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