Your patient has a hematocrit of 56%. You recall from your anatomy and physiology class that high hematocrits are often a sign of blood doping by athletes. However, your patient is an elderly man suffering from the flu. What is most likely accounting for his elevated hematocrit?

Remember that blood is a proportion.
He is dehydrated from the flu.

If your patient is severely ill and not drinking enough fluids, especially if he has a fever, the ratio of cells to fluid will be shifted.