Q: I'm worried I might have hypothyroidism—how can I tell?

A. Well, you certainly wouldn't be alone if your thyroid was out of sorts, and chances are good that you may not know it. An estimated 27 million Americans have either an overactive or underactive thyroid gland, but fully half of these haven't been diagnosed yet. Thyroid problems occur more often in women, and hypothyroidism (underactive thyroid) becomes more likely the older you get or if you have a family history of thyroid problems. In addition, thyroid issues become more likely in the few months after giving birth.

The thyroid gland pumps out hormones that affect many body processes, so symptoms of an underactive thyroid can be varied and include fatigue, forgetfulness, depression, heavier periods, dry hair and skin, mood swings, weight gain, intolerance to cold, hoarse voice, and constipation. If you suspect a problem with your thyroid, ask your doctor for a blood test to assess your thyroid hormone levels. If your levels run too low, your doctor will put you on thyroid hormones to make up the difference.

This Q&A was written by Victoria Dolby Toews, MPH, author of the The Soy Sensation (McGraw-Hill, 2002) and The Green Tea Book (Avery, 1998).