It is estimated that approximately one in eight women will suffer from some form of thyroid disorder in her lifetime. During different phases of a woman’s life, the thyroid gland must adjust to meet the demands of physical growth or hormonal changes with pregnancy and menopause, as well as function as the metabolic pacemaker for many processes throughout the body. The thyroid gland, located just below the Adam’s apple in the lower part of the neck, is a small butterfly-shaped gland which receives its direction from the pituitary gland located in the brain. The pituitary gland controls the thyroid much like a thermostat controls your home’s temperature. When thyroid hormone production decreases, the pituitary senses this drop in hormone and sends a signal called Thyroid Stimulating Hormone (TSH) to the thyroid gland. TSH stimulates the thyroid to produce thyroxine (T4), which is turned into a more potent active form, T3, in various places of the body. A rise in the level of T3, in turn, signals the pituitary to “shut off” the production of TSH.
The influence of this seemingly simple feedback system is responsible for nearly all bodily functions. Thyroid hormone affects everything from appetite, mental processes, skin, hair and nails to a woman’s menstrual cycle and her fertility. The thyroid gland also influences cardiovascular health and the skeletal and central nervous systems. Therefore, it is easy to understand that when the thyroid is not functioning properly, many body systems can be affected, leading to a number of worrisome symptoms.
Thyroid disorder is marked by either an overactivity or underactivity of the thyroid gland. Overactivity (hyperthyroidism) occurs when too much thyroid hormone is being produced. In contrast, hypothyroidism occurs when not enough thyroid hormone is produced.
Hyperthyroidism causes processes in the body to “speed up.” Eighty percent of hyperthyroidism is caused by an autoimmune disorder known as Graves’ disease, and, as women are more likely to have an autoimmune disorder than men, it follows that nine out of 10 people who are hyperthyroid are women. Women with Graves’ disease can experience an increase in anxiety, rapid heartbeat, heart palpitations, unexplained weight loss, heat intolerance, muscle weakness, fatigue and changes in the menstrual cycle, which can lead to infertility problems. There is no cure for the root cause of this disease, which causes such mayhem within the body. Therefore, treatment involves rendering the thyroid gland inactive to stop the overproduction of hormone. This is usually accomplished by treating the thyroid with radioactive iodine or antithyroid drugs or removing the gland in surgery.
Hashimoto’s disease, another autoimmune diagnosis, is the leading cause of hypothyroidism in women. Contrary to hyperthyroidism, symptoms of hypothyroidism are almost exactly the opposite. Weight gain, depression, cold intolerance and a slow pulse are just a few of the symptoms women may experience. Sometimes difficulty swallowing due to an enlarged thyroid gland, often caused by constant stimulation of TSH, can be a first clue that something is wrong with the thyroid gland. Hypothyroidism is usually treated with daily thyroid replacement hormone, which is most commonly a combination of the thyroid hormones thyroxine and T3. Treatment of hypothyroidism can make a world of difference in a woman’s mood, appearance and energy level, and may help restore a normal menstrual cycle, thus improving infertility.
Because either too much or too little thyroid hormone can impact a woman’s menstrual cycle and, subsequently, her fertility, the thyroid gland plays an important role in reproduction and pregnancy. In infertile women, the prevalence of thyroid disease caused by autoimmune disorders such as Graves’ disease or Hashimoto’s disease is significantly higher than in women who have been able to conceive. If able to conceive, women with a thyroid disease caused by an autoimmune disorder also carry an increased risk of miscarriage in the first trimester.
Hypothyroidism during pregnancy is associated with high blood pressure during pregnancy and low birth weight. Women on thyroid replacement therapy may require an increased dose of their medication during pregnancy. Graves’ disease can be much more serious to both mother and baby if diagnosed during pregnancy. However, like most autoimmune disorders, the Graves’ and Hashimoto’s diseases tend to improve as pregnancy progresses. Postpartum thyroid dysfunction has been reported in 5-10 percent of women within a year after delivery, with, again, autoimmune disease being the cause. Fatigue, hair loss and depression—often thought to be common occurrences in early motherhood—can actually be a sign of thyroid dysfunction and should be investigated, particularly if there is a strong family history of autoimmune disease.
On the other end of the continuum, thyroid disease after menopause can have serious consequences. As postmenopausal women are already at an increased risk for heart disease, women with untreated hypo- or hyperthyroidism have an even greater risk of cardiovascular events, as well as an increased risk for osteoporosis. The incidence of mild hypothyroidism or hyperthyroidism, without any symptoms, increases from 10 percent in premenopausal women to 20-25 percent in post-menopausal women. Because symptoms can be very similar, hypothyroidism is often missed in perimenopause and menopause. Many women attribute weight gain, fatigue, depression and mood swings to menopause or “just getting old.” In fact, these could be caused by an underactive thyroid, and can easily be treated with medication.
No matter what stage of life thyroid disorders strike—at puberty, the reproductive years, during or after pregnancy or at menopause—a woman’s body is uniquely and dramatically affected. Our bodies require a delicate balance of hormones in order to maintain good health. Since so many symptoms of thyroid disease are vague and might be masked by other health problems common to women, thyroid disorders are often misdiagnosed. As women continue to educate themselves about their bodies, they not only aid in an accurate diagnosis but empower themselves to make better choices in their own healthcare management. TPW