The Mean Platelet Volume test is used to calculate the number of platelets in the blood. Often included in the complete blood count test, this test is used for regular health checkups also. The platelets in the body are useful is blood clotting and thus, its increased or decreased volume can have a dominant impact on the overall well-being of the individual. This test diagnoses the individual’s health, pertaining to blood and its concentration which plays a significant role in determining the body’s response to injuries.