Final answer:
The measure of the percentage of the total blood volume that is comprised of platelets is referred to as the plateletcrit (PCT). Of the options provided, 'PCT' is the correct answer. PCT is distinct from hematocrit, which measures the percentage of erythrocytes in blood.
Step-by-step explanation:
The measure of the percentage of the total blood volume that is comprised of platelets is known as the plateletcrit (PCT). The PCT is a measure similar to the hematocrit (HCT), but instead of measuring erythrocytes, it focuses on platelets. In a complete blood count (CBC), along with PCT, there are other indices related to platelets, such as mean platelet volume (MPV), platelet distribution width (PDW), and platelet-large cell ratio (P-LCR). However, for the specific question on the percentage representation of platelets in blood volume, the correct answer is d. PCT.
An understanding of the hematocrit is also useful for this question. Hematocrit is the volume percentage of erythrocytes in a sample of centrifuged blood, and in a typical test, if a patient's hematocrit is 42 percent, this means that approximately 58 percent of the patient's blood is plasma, as the remaining component of blood after removing erythrocytes (100 minus 42). Since the portion of platelets is usually less than 1 percent, it does not significantly alter the plasma percentage.
Hence, when determining the volume represented by platelets in the total blood volume, PCT is the appropriate measure among the options given.