The platelet parameter PDW refers to the

• A. Average platelet volume
• B. Cell weight versus density
• C. Capacity to adhere to foreign surfaces
• D. Variation in platelet cell size

Answer: (D)

The main concept here is that PDW measures how much the sizes of platelets vary. It reflects the distribution of platelet sizes in the blood, so a high PDW means there’s a wide range of platelet sizes (some large, some small), while a low PDW indicates more uniform platelet sizes. This is different from the average platelet size, which is MPV. The other options describe the average size, a concept like weight or density, and a platelet function property (adhesion), none of which describe what PDW evaluates.