Grandma told you that it was normal to lose 100 hairs a day. How did she know? Did she ever count them? Was that an average, or specific to you? Is it what you should expect at the age of 16 or 60?
No one knew. Until now, even dermatologists who specialize in hair loss took it as an unsubstantiated given that it's normal to lose 100 hairs a day, based on the wisdom of the ages and backed by a mathematical equation. The equation assumes that the average head has 100,000 hairs, 10% of which are in the telogen, or resting, phase. That means they're no longer growing, they're getting ready to give it up, but they're going to take about 100 days before they bail out and hit the shower floor, curl up in the sink drain or entwine themselves around the bristles of your brush. So 10% of 100,000 is 10,000. Divide that by 100 days and you get a daily loss of 100 hairs a day.........
Full article... http://latimesblogs.latimes.com/booster_shots/2008/06/balding-test-yo.html
The study was funded by Merck & Co., which makes Propecia, a drug to treat hair loss. And Miller is a consultant for Pfizer Inc., which makes Rogaine and is testing other drugs for hair loss. But neither company influenced the study, he says.