Millions of people, most of them women, suffer from thyroid disease. When your body produces too little thyroid hormone, the hormone responsible for metabolism, heart rate, and mood, you are said to have hypothyroidism, or an underactive thyroid. If your body makes too much of the hormone, you’re said to have hyperthyroidism, or an overactive thyroid. Thyroid hormone is responsible for everything from your basal metabolic rate—the rate at which your body uses oxygen and energy to function—to the growth of your hair, skin, and nails. But when you don’t have the right amount, you may notice changes in bodily functions.
The symptoms: Hypothyroidism (too little hormone) may cause a host of symptoms, including unexplained weight gain, fatigue, constipation, depression, and difficulty concentrating. Hair, nails, and skin may become more brittle and break more easily. It’s more common in women, especially over the age of 50, says Theodore C. Friedman, MD, MPH, chief of the division of endocrinology, metabolism, and molecular medicine at Charles Drew University in Los Angeles and coauthor of The Everything Guide to Thyroid Disease (Adams Media, 2007). It affects about 5 percent of the US population but is nearly 10 times more frequent in women.
Hyperthyroidism (too much hormone) may cause inexplicable weight loss, heart palpitations, nervousness, irritability, diarrhea, moist skin, muscle weakness, and a startled appearance of the eyes. You may also experience hair loss as metabolism speeds up. Hyperthyroidism is much less common than hypothyroidism and affects about 1 percent of the US population.
The tests: A blood test measures thyroid-stimulating hormone, which is produced by the pituitary gland in an attempt to coax the thyroid to make thyroid hormone. Excess TSH usually indicates hypothyroidism, while abnormally low levels suggest hyperthyroidism.
What you can do: Your doctor may prescribe a thyroid hormone medication to restore levels to normal. Regular TSH tests might be done to ensure an adequate dosage.