Last week we discussed the causes and manifestations of an underactive thyroid gland--hypothyroidism.
This week, we will review the opposite condition caused by an excessive amount of thyroid hormone--hyperthyroidism. Keeping in mind that the thyroid gland is a master controller of metabolic functions in the body, many symptoms of hyperthyroidism are understandable and predictable.
Variable from person to person, and sometimes appearing separately and other times in combinations, common symptoms include nervousness, fidgeting and irritability. The heart rate may be fast and/or irregular. Heat intolerance and sweating are seen, as is weight loss. Uncommonly, a patient’s eyes may bulge out, or they seem to stare without blinking.
There are many etiologies of hyperthyroidism. The most common is Grave’s Disease, a condition in which a self-produced antibody stimulates thyroid gland cells to produce more thyroid hormone. This is the condition in which bulging eyes are often seen. Small, non-cancerous growths of the thyroid gland, called nodules, may produce excessive hormone. Inflammation of the thyroid gland, caused by viruses or related to pregnancy, may allow stored hormones to be released from the gland and cause symptoms of hyperthyroidism.
Like hypothyroidism, hyperthyroidism is easily diagnosed in the doctor’s office through simple, readily available blood tests. However, the testing to diagnose the cause of excess thyroid hormone production is a little more complicated and may involve ultrasound or nuclear medicine testing.
Treatment may involve medications, radiation or surgery--many factors play into this decision including the etiology of the hyperthyroidism and age of the patient. The medications (antithyroid drugs) work directly to decrease how much thyroid hormone is made. Radioiodine is another frequent therapy and works by permanently destroying thyroid cells.
Many patients treated in this manner will ultimately develop hypothyroidism and will need to take replacement thyroid hormone by mouth. Thyroid surgery is probably the least common of these three treatments, but may be used if the size of the gland is very big, if medication is not tolerated or if there is a concern about possible thyroid cancer.
Overall, women are 5-10 times more likely to get hyperthyroidism than men. A personal history or family history of thyroid dysfunction increases your risk. The condition is also more common in people over the age of 60, and may manifest without the typical signs and symptoms mentioned above. Depression or apparent dementia may be caused by an overactive thyroid.
Between last week and this week we have covered the “ups and downs” of thyroid function. For more information on hyperthyroidism, please visit www.endocrine.niddk.nih.gov/pubs/Hyperthyroidism.