Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

Which of the following applies to a hematocrit?

1. Expressed as a decimal fraction

2. Represents the space occupied by the packed RBCs

3. Closely parallels the values of hemoglobins and RBC

4. All the above

The correct answer is: All the above

The hematocrit is the proportion of blood volume that is occupied by red blood cells (RBCs). The packed cell volume, which hematocrit measures, is crucial in evaluating conditions such as anemia and polycythemia. It's expressed as a percentage (for example, a hematocrit of 45% indicates that 45% of the blood's volume consists of packed red blood cells). While hematocrit can be expressed as a decimal fraction (for instance, 0.45 for 45%), it is not exclusively presented in that format; thus, this point is relevant but not definitive. The hematocrit also closely parallels hemoglobin values and the red blood cell count because these measurements are interrelated. A decrease in RBCs typically corresponds with a low hemoglobin level and reduced hematocrit, which is significant in hematological assessments. Since all these statements are relevant to the understanding of hematocrit—its representation, the space it denotes concerning RBCs, and its relationship with hemoglobin and RBC counts—the correct answer encompasses all of these aspects.