Fatigue, weight gain, hair loss and decreases in memory are, for many people, attributed to symptoms of aging. However, aging may not be the cause. These symptoms may be the result of an underactive thyroid gland or hypothyroidism.
According to one professional endocrinology society, the way most doctors test thyroid function may not be as sensitive at detecting hypothyroidism as commonly believed. This means that there are millions of people who experience symptoms of hypothyroidism, yet are told that their thyroid is functioning fine.
The thyroid gland is located in the lower part of the neck and has been of interest to physicians since the Middle Ages. It was not until the beginning of the 20th century that the role of the thyroid was defined.
The thyroid gland controls, to a great extent, the body's metabolism. It does this through the production of thyroid hormones, primarily triiodothyronine (T3) and thyroxine (T4). The thyroid also makes calcitonin, another hormone that has a role in blood calcium levels. The production of T3 and T4 is controlled by a thyroid-stimulating hormone made by the pituitary gland in the brain. If the body needs more thyroid hormone, the brain produces more TSH. If less thyroid hormone is needed, less TSH is produced.
An underactive thyroid may not produce enough T3 or T4 to meet the demands and stresses of daily living. This condition is often underdiagnosed because the symptoms can appear slowly over time. Symptoms can include anxiety, difficulty losing weight, hair loss, mood changes, menstrual changes, severe fatigue, sallow (yellow) skin and difficulty with memory. These symptoms are often attributed to the aging process or simply stress.
There are well established and accurate tests for thyroid function, but the interpretation of the test results is the key to diagnosing an underactive thyroid. The commonly used reference ranges for TSH may be too wide and probably miss many people with an underactive thyroid. Most diagnostic laboratories have a reference range for TSH that is approximately between 0.5 and 5.0 micrograms per deciliter. However, in 2003, the American Association of Clinical Endocrinologists recommended a much narrower range of 0.3 to 3.0 micrograms per deciliter.
Using the broader range of 0.5 to 5.0 micrograms per deciliter, only about 5 percent of the U.S. population (about 15 million people) could be diagnosed as having an underactive thyroid. With the tighter range of 0.3 to 3.0 micrograms per deciliter, almost 20 percent of the population (60 million people) would be diagnosed with an underactive thyroid gland.
An underactive thyroid can increase the risk of Alzheimer's disease, heart disease and even osteoporosis. There are a number of medications used for the treatment of hypothyroidism including T4, T3 and combinations of T3 and T4. Modest iodine supplementation may also help, but is rarely a cure. Be wary of supplements used to keep the thyroid "healthy." They usually are made from powdered animal thyroid gland and may contain substantial amounts of T4 and T3. They are not standardized and may cause more problems than they solve.
• Patrick B. Massey, M.D., Ph.D is medical director for complementary and alternative medicine for the Alexian Brothers Health System. His website is www.alt-med.org.