Dr. Holly Phillips suggests that you check yourself for any changes in appearance.
She's talking about things like observing that while your hair used to be oily you now have dry hair, or that your former unibrow has been replaced by thinning eyebrows. You may have noticed changes in finger nails, like developing new ridges or turning a different color.
Here are a few things you can pick up on from some of these changes in appearance.
Dry hair could be the result of thyroid disease or iron deficiency. Thinning eyebrows on the outer corners could mean insufficient thyroid.
Brittle finger nails could point to thyroid disease, or possibly vitamin B12 or iron deficiency. Certain types of lines across the finger nails can indicate a risk of heart failure or heart disease. Finger nails that have turned brown or yellow could be a sign of fungal infection.
"It's 'incredibly important,' Phillips says, to carefully check your body for such indicators and recognize subtle changes. Even if the signs aren't dangerous, when you notice a change, your body is trying to tell you something."
http://www.cbsnews.com/stories/2010/06/12/earlyshow/saturday/main6575052.shtml