Doctors use average blood test numbers to decide what's 'normal,' but those averages include sick people, so healthy people might be told they're unhealthy—and real health problems might be missed.

This study found that even healthy young men have different levels of certain body chemicals depending on the season, which means using one standard number for everyone might make normal differences look like problems. That supports the idea that current medical ranges are too broad and miss real health issues.

Doctors usually compare your blood test results to what's average for most people, but this study shows that’s not always accurate—your body’s normal is different from someone else’s. Using your own past results as a baseline helps spot real problems better than comparing you to a crowd.