Medical Technologist Test Hematology 3

Question 1

Which parameter directly measures the variation in red blood cell size?

Accepted Answer

RDW

Answer

Red cell distribution width (RDW) quantifies anisocytosis; an elevated RDW indicates heterogeneous RBC sizes.

Question 2

A platelet count below which threshold is considered thrombocytopenia?

Accepted Answer

150,000/µL

Answer

Thrombocytopenia is defined as a platelet count below 150,000/µL (150 × 10⁹/L) in adults.

Question 3

Heinz bodies in red blood cells are composed of which substance?

Accepted Answer

Denatured hemoglobin

Answer

Heinz bodies are inclusions of denatured, precipitated hemoglobin seen in G6PD deficiency and oxidative hemolytic anemias.

Question 4

Which type of anemia is characterized by an MCV less than 80 fL?

Accepted Answer

Microcytic anemia

Answer

Microcytic anemia (MCV <80 fL) is most commonly caused by iron deficiency, thalassemia, or anemia of chronic disease.

Question 5

What is the function of von Willebrand factor (vWF) in hemostasis?

Accepted Answer

Mediates platelet adhesion to damaged endothelium

Answer

vWF bridges platelets to collagen at sites of vascular injury by binding both platelet GPIb receptors and subendothelial collagen.

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