The symptoms of an underactive thyroid—fatigue, feeling cold, weight gain, dry skin and hair, and constipation—can be associated with many other diseases and disorders, making the condition impossible to diagnose definitively without a blood test. And many people have mild thyroid disorders that cause no symptoms at all—but that may nevertheless be harmful. Endocrinologists recommend that people with the following risk factors consider periodic testing for thyroid disease.
Family history. In many cases, hypothyroidism runs in families. People who have relatives with thyroid disease should pay attention to symptoms and have occasional tests, experts say.
Autoimmune disorders. People with multiple sclerosis, type 1 diabetes, rheumatoid arthritis, and Addison's disease and other autoimmune disorders are at increased risk for hypothyroidism and should get tested regularly, according to the American Thyroid Association.
Heart failure. Hypothyroidism is associated with increased rates of heart failure, in which the heart fails to pump efficiently; it may also increase the severity of heart failure. So anyone with congestive heart failure should be tested for thyroid problems, says Douglas Baer, a professor of medicine and epidemiology at the University of California-San Francisco.
Age. Among both men and women, the prevalence of hypothyroidism increases with age. Medical organizations disagree on how often older people should be tested, but most agree that women should get tested periodically starting during menopause, while men should start getting tested in their 60s. The ATA recommends that all women over 35 have a thyroid test every five years.
Pregnancy. While being pregnant isn't known to increase the risk of having an underactive thyroid gland, it could make the condition more harmful to both mother and fetus. Thyroid hormone is essential during fetal development, and even mild hypothyroidism in pregnant women has been linked to preterm birth, miscarriage, and vision problems in their babies. Although official recommendations say that only women with other risk factors need to be tested, some experts argue that all women of reproductive age should be evaluated for thyroid disease.