On the first day of summer football practice, all players were required to have a physical. Each student was handed a plastic cup and directed to the restroom. "Please provide me with a sample," the physician requested. The athletes had no idea how much could be learned about their health and behavior from a small urine sample.

Immediately after handing over their samples, Philip and Seth were sent home and told to drink plenty of water before practice the next day. The next day, Andrew was told to see his family physician because he could have diabetes. Several days later, another student was dropped from the team for violating the school's well-known antidrug policy. How was all of this information gained from a urine sample? As you read this chapter, look for clues to help you discover what can be learned about the body by simply examining what leaves it. Solve the mystery.