Hyperthyroidism affects about 1% of people but is more common in older adults. It is often more serious among older adults because they tend to have other disorders as well.

Hyperthyroidism in older adults often results from Graves disease. Almost as often, hyperthyroidism is caused by the gradual growth of many small lumps in the thyroid gland that produce thyroid hormones (toxic thyroid nodules).

Older adults are more likely to be treated with medications that can cause hyperthyroidism. The most common is amiodarone, a medication used to treat heart disease but which may stimulate or damage the thyroid gland.

Hyperthyroidism can cause many vague symptoms that can be attributed to other conditions. Typically, symptoms in older adults differ from those in younger people.

Among older adults, the most common symptoms are weight loss and fatigue. The heart rate may or may not be increased, and the eyes usually do not bulge. Older adults are also more likely to have abnormal heart rhythms (such as atrial fibrillation), other heart problems (such as angina and heart failure), and constipation.

Occasionally, older adults sweat profusely, become nervous and anxious, and have hand tremors and frequent bowel movements or diarrhea.