Hyperthyroidism is a condition characterized by high levels of hormones produced by the thyroid gland. It is also known as thyrotoxicosis. Hypothyroidism may be associated with diffuse toxic goiter and less frequently with toxic nodular goiter or toxic adenoma. Most of these conditions of the thyroid gland occur in the early to mid adulthood. However, toxic nodular goiter may only arise after the age of 50 years despite the non-toxic form existing from earlier in life.
Although hypothyroidism (underactivity of the thyroid gland) is more common in the elderly, hyperthyroidism may also be seen in seniors. Excessive thyroid hormone causes generalized increase in metabolic rate of all body tissues. Hyperthyroidism is an excessive functional activity of thyroid gland that can be caused by an auto-immune condition known as Graves’ disease or excessive replacement of thyroid hormones in hypothyroidism.
Due to the presence of high levels thyroid hormones, a number of symptoms can be seen in hyperthyroidism. This includes :
With Grave’s disease, the eyes appear to pop out of the sockets, a condition known as exopthalmus. The skin is usually is warmer than normal and has a flushed appearance. The heart rate is generally increased in patients with hyperthyroidism. Palpitation may often be present and the blood pressure is typically elevated. The thyroid gland becomes diffusely enlarged, smooth, asymmetrical and nodular. The swelling over the gland moves while swallowing.
The most common cause of hyperthyroidism includes autoimmune disorders known as Graves’ disease. In this condition the entire thyroid glands overproduces thyroid hormones due to disturbances in feedback mechanisms in between the thyroid gland and the pituitary gland. The condition is hereditary in nature. The trigger factors initiating Graves disease include head and neck radiation, stress, smoking and certain viral infections.
Hyperthyroidism can also be caused due to formation of a nodule within the gland. This is a less common cause of hyperthyroidism in most cases overall, however it is significant in the elderly. The condition is termed as toxic nodular goiter and is a non-cancerous growth of the gland. Thyroditis, a condition where there is inflammation of the thyroid gland, can be responsible for increased thyroid hormone production.
Antithyroid drugs include carbimazole, methylthiouracil and potassium perchlorate.The drugs are usually prescribed in combination with beta blocker drugs such as propranolol. Beta blockers are contraindicated in patients with cardiac failure, asthma and diabetes. This is a major concern when treating hyperthyroidism in the elderly, as cardiac conditions and diabetes are more common in seniors.
Surgical treatment such as subtotal thyroidectomy is the treatment of choice in young patients, who are too young to undergo radioactive iodine therapy. The surgical options are also preferred in patients unresponsive or allergic to antithyroid drugs. In patients over 40 years of age, radioactive iodine therapy is considered. Since thyroid hormones are produced from iodine, the radioactive forms are taken up by the thyroid gland and ultimately the gland is destroyed. This reduces thyroid hormone production.