Believe it or not, you can tell a lot about a person’s health by looking at his or her hair.

We recently received this email from a viewer:

Hi Dr. Manny,
If you lose your hair from a thyroid condition, will it grow back after treatment?
Thanks,
Dulce

Hair cells are some of the fastest growing cells in the body. So when your body is under stress from illness, hair cells can shut down to redirect the energy elsewhere to help heal what ails you.

According to the Academy of Dermatology, almost half of the American population experiences thinning hair by the age of 40, but people with certain thyroid conditions may start to lose their hair even earlier and more quickly.

“The good news is that your doctor can prescribe thyroid hormone medication to help your hair grow back,” said Dr. Jennifer Landa, chief medical officer for BodyLogicMD. “The first thing that you’ll notice is a slowing of the hair loss, and then the hair will start to grow back, and ultimately it will grow thicker and stronger. But this can take several months.”

Landa added that if a patient has been on thyroid hormone medication for an extended period of time and is not seeing results, he or she should ask for a free T3 test – which measures for a specific thyroid hormone called triiodothyronine.

“Most medication that we get for thyroid is T4 (thyroxine), and most patients do very well on that,” she said. “But there are many patients that would benefit from the addition of some T3 into their thyroid hormone regimen to help them grow back hair longer and stronger.”

Do you have a health question for Dr. Manny? Please send it to DrManny@foxnews.com.