Q: How is hypothyroidism different from hyperthyroidism?

A: Hypothyroidism is underactivity, and hyperthyroidism is overactivity, of your thyroid gland.

Your thyroid gland affects pretty much every part of your body. The hormones it secretes regulate your metabolism and your ability to tolerate heat or cold. They can change your energy levels and mood, and — if you’re a woman — your periods.

• In hypothyroidism, you don’t produce enough thyroid hormone. This slows everything down. You can feel fatigued, depressed and hypersensitive to cold. You can gain weight and develop constipation.
• In hyperthyroidism, you have too much thyroid hormone. This revs everything up. You can feel anxious, experience insomnia, and get hot, sweaty and flushed. You can lose weight without meaning to and develop heart palpitations.

So it’s vital to be sure your thyroid is functioning well. If you’re experiencing any of these symptoms — or if you’re just not feeling like yourself — tell your doctor.

Mention any family history of thyroid conditions, which will put you at much higher risk for developing a thyroid problem.

Your doctor will run some labs to find out whether you might have hypothyroidism, hyperthyroidism or another condition that can be addressed so you feel better.

— Endocrinologist Mary Vouyiouklis-Kellis, MD