HEALTH TOPICS 
The symptoms of an overactive thyroid gland (hyperthyroidism) are so wide-ranging — affecting your mood, energy, body temperature, weight, heart, and more — that it may be difficult to get the correct diagnosis right away.
The risk of hyperthyroidism increases with age. The diagnosis of thyroid disease can be particularly tricky in older people.
One study, conducted in France, compared signs and symptoms in elderly patients with an overactive thyroid with the symptoms experienced by younger patients. The older patients were less likely to show the typical signs of increased sweating, heat tolerance, hand tremors, nervousness, excessive thirst, and increased appetite. While older people can experience these classic symptoms, the following symptoms may also provide important clues to possible thyroid problems.
- Depression. An older person with hyperthyroidism is more likely than a younger person with the disease to develop depression.
- Heart failure. The heavy burden an overactive thyroid places on the heart can lead to heart failure — a condition where the heart cannot pump blood through the body effectively. Symptoms of heart failure include shortness of breath, swelling in the ankles, and weakness and fatigue.
- Atrial fibrillation. In one study, 35% of older people with hyperthyroidism experienced the disorganized heart rhythms of atrial fibrillation, while only 2% of younger patients did.
- Excessive weight loss. A younger person with hyperthyroidism may experience some weight loss, but older people tend to lose even more weight, and may even appear malnourished. Muscle weakness can be a side effect of such severe weight loss.
To gain a greater understanding of hyperthyroidism, hypothyroidism and how your thyroid works, buy the special health report, Thyroid Disease from Harvard Medical School.