Dr Rajeev Sharma
The term “hyperthyroidism” refers to a condition where thyroid gland is overactive and produce excess hormones leading to signs and symptoms. Thyroid gland is butterfly shaped gland situated in front of the neck. It has 2 wings that are called lobes that are connected with each other by a structure called Isthmus. Thyroid gland produces hormones called thyroxine (T4) and triiodothyronine (T3). Thyroid hormone controls the body metabolism and helps the body to stay warm and keep the organs like heart, muscles, and gut working. When thyroid gland is overactive, it produces excess of T4 and T3.
What are signs and symptoms of hyperthyroidism?
As mentioned above, in normal conditions, thyroid hormone helps the body metabolism. When thyroid becomes overactive, it increases the metabolism thus producing various signs and symptoms. Classically, the common signs and symptoms are unintentional weight loss in spite of having good appetite (good food intake), shaking of fingers (tremors), nervousness (anxiety), racing of heart (palpitation), sleeping problems (insomnia-unable to sleep), increased sweating, more frequent passing of stools (frequent loose motions). In females, in addition to the symptoms described, they might have abnormalities in menstrual periods. Patient may feel energetic all the time but as disease becomes worse he or she may feel tired. On examination, your doctor may see signs of bulging eyes (proptosis), fast heart rate (tachycardia) and/or swelling in front of neck (goiter-enlarged thyroid gland). Usually young patients can tolerate the excess thyroid hormone without much issues but elderly (older) patients can get fast and irregular heart rate (arrhythmias) that can be life threatening.
What are the causes of hyperthyroidism?
The most common cause of overactive thyroid gland is a condition called “graves disease”. In this condition, your own body produces substances known as autoantibodies that stimulate the thyroid gland continuously and does not let it rest. This results in excess hormone production and release into the blood. It is more commonly seen in women and may run in families. The second common cause of hyperthyroidism is a condition called “toxic goiter”. This is the result of a growth in thyroid gland (nodule) that becomes wild (autonomous/uncontrolled) from the surrounding normal gland cells and secretes the hormone continuously. There can be single or multiple nodules that can become autonomous. Rare causes include a temporary (transient) condition called as “thyroiditis” in which infection or inflammation cause death of thyroid cells containing thyroid hormones thereby releasing the preformed hormones into the blood. Lastly, patients who are taking thyroid medication called levothyroxine (e.g. thyronorm, eltroxinetc) for underactive thyroid can also have similar signs and symptoms if the dose of the medication is too much.
How is hyperthyroidism diagnosed?
The diagnosis of hyperthyroidism is suspected because of signs and symptoms that were mentioned before. However, patient is advised to see a medicine doctor or hormone specialist (endocrinologist) for further work up and treatment. Your doctor will order blood tests like thyroid stimulating hormone (TSH) and thyroxine (T4) and triiodothyronine (T3). To rule out graves disease, special test for antibodies such as thyrotropin receptor antibodies (TRAb) and thyroid stimulating antibodies may be ordered. If these antibodies are high along with low TSH and elevated T4 and/or T3, a diagnosis of graves disease can be made reasonably. However, many times a patient may need to get a picture of thyroid gland called “thyroid scan”. This is a special test that is performed only in approved Nuclear Medicine facility/department to differentiate between the causes of hyperthyroidism (graves, toxic nodule or thyroiditis).
How do we treat hyperthyroidism?
There are 3 ways we can treat hyperthyroidism (medication, radioactive iodine therapy and surgery). Usually either medication or radioactive iodine therapy is used to treat hyperthyroidism depending upon patient condition, cost and other factors. Radioiodine treatment and surgery cure the problem for ever but medicine only controls it and has to be taken lifelong. Other than the specific treatments discussed below, almost all patients are treated with a special class of medication called “beta-blockers” to help control heart rate. Once the thyroid condition improves, beta blocker can be stopped.
Hyporthyroidism (underactive thyroid)
In this condition thyroid gland does not produce enough thyroid hormones for body to function. This leads to symptoms opposite to overactive thyroid. Unlike hyperthyroidism, “hypothyroidism” is not curable but easy to treat with a thyroid hormone supplement tablet (levothyroxine) taken once a day for whole of life.
(The author is Assistant Professor of Medicine and Oncology Division of Endocrinology Roswell Park Cancer Institute & University at Buffalo Buffalo, New York-USA)
Dr Rajeev Sharma