I’m a bit of a hypochondriac. It’s not that I’m a germaphobe or that I run to the doctor at the slightest sign of a fever, but I have a deep fear that one day I’ll walk into a doctor’s office and hear, “I have bad news.”

I’ve lost both parents to cancer and, besides my grandma, every relative on my father’s side has had cancer. I’m also a health journalist, and anyone who reads enough about disease and abnormality will naturally start to wonder when their own luck will run out.

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More and more we hear stories about healthy young men who suddenly pass away without the slightest inkling they were ever sick. Just last year I was out for a run, when I passed an ambulance. I was shocked to see that the person they were tending to was a run buddy—someone I’d passed on previous jogs, never talked to, but smiled to in acknowledgement, like, “Hey, I recognize you, and it’s great that we’re both out here doing something positive for our health.” The man was in his mid-40s and appeared to be in great health. On my next jog, I learned my run buddy had passed away from a heart attack.

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“Most people have no idea that health risks are looming in the background,” says David Quig, Ph.D., vice president, scientific support, for Doctor’s Data in Chicago. Luckily, there are a number of tests that can help predict your risk for adverse health effects before any symptoms appear. Here’s a look at the most important health tests and why one could save your life.

Next: The health tests that could save your life >>>