By Yolanda Smith, BPharm
The management of hyperthyroidism depends on several factors, including the individual patient, the severity and the cause of the condition, which must be established during the diagnostic process.
There are three main treatment techniques used for hyperthyroidism: pharmacotherapy, radioactive iodine and surgery.
Antithyroid agents such as carbimazole or propylthiouracil (PTU) may sometimes be used to manage hyperthyroidism by inhibiting the production of hormones in the thyroid gland.
Carbimazole is more commonly used than PTU, due to the more severe side effects associated with the latter.
Both drugs are able to control the function of an overactive thyroid gland in an efficient manner, without causing permanent damage to the gland.
Anti-thyroid medications carry a small risk of allergic reactions, and approximately 1 in 20 patients experience a reaction.
Signs of an allergic reaction to the drug may include skin rash, hives, fever and joint pain.
Rarely, patients may exhibit a decrease in their white blood cell count, which is a serious effect as it results in reduced resistance to infection.
Some patients may also be affected by agranulocytosis, involving the complete eradication of white blood cells, which can be fatal in rare cases.
Beta-blocker drugs such as propranolol, atenolol and metoprolol are often used to inhibit the action of thyroid hormones on the cardiovascular system.
They may be used alongside any other treatment used in hyperthyroidism.
They are of immediate effect in controlling symptoms such as heart palpitations and hand tremors, but have no effect on the level of thyroid hormones in the blood.
Radioactive iodine can be used to damage or destroy the thyroid cells involved in the production of thyroid hormones, thus reducing their concentration in the blood.
Iodine is needed in the process of thyroid hormone synthesis. Taking advantage of this fact, radioactive iodine is administered to the patient, and is taken up by the cells of the thyroid, where it affects their ability to function normally.
Radioiodine is usually administered as a single oral dose, which is then absorbed into the bloodstream and travels to the thyroid cells quickly. Any radioactive iodine that is not taken up by the thyroid gland is excreted from the body in a matter of days.
The radioactive iodine in the thyroid gland typically takes several weeks or months to destroy the overactive cells in the thyroid gland. Many patients will require simultaneous symptomatic pharmacological treatment to control the immediate manifestations of the elevated hormone level.
Following treatment, the enlarged thyroid gland or thyroid nodules shrink, along with a reduction in the production of thyroid hormones to normal or below normal levels.
A few patients may need repeated doses if the hormone level remains high, but a few may develop hypothyroidism and require ongoing thyroid hormone supplements.
Women in the childbearing age group should take precautions against conception for at least 6 months after this treatment, while men should exercise equal care against fathering children for four months.
In some cases, surgical removal of all or part of the thyroid gland may be required, in order to permanently reduce the production of thyroid hormones. This is called a partial or total thyroidectomy.
It is associated with some risks, however, and is only undertaken after the condition is adequately controlled with pharmacological management, such as anti-thyroid agents or beta-blockers. It is usually advised only if:
- a goiter is recurrent and associated with hyperthyroidism symptoms and signs, after pharmacotherapy and/or radioiodine
- the goiter is large and associated with symptoms of obstruction
- pharmacotherapy is unadvisable for any reason
- severe Graves’ disease is present
In most cases, non-radioactive iodine drops are administered in the days preceding surgery to gradually reduce the blood supply to the thyroid gland.
With this precaution, the vast majority of thyroid surgeries (>99%) are not associated with major complications. However, some patients may suffer inadvertent damage to the parathyroid glands or the vocal cords.
Following surgery, the thyroid gland can no longer produce thyroid hormones as before. Therefore, most patients are affected by hypothyroidism. To manage this, a thyroid hormone supplement is given once a day to replace thyroxine and triiodothyronine.
Referral to an Endocrinologist
An endocrinologist has specialized knowledge and expertise in the function of the thyroid gland and is often able to make the most coherent decisions for treatment of hyperthyroidism.
For this reason, general practitioners with a patient affected by hyperthyroidism should consider referring the patient to an endocrinologist, particularly for cases that require further investigation or when the best treatment path is unclear.
Reviewed by Dr Liji Thomas, MD.
Last Updated: Jun 23, 2016