Thyroid hormone replacement therapy
Thyroid abnormalities are common and I see many patients with thyroid disease. A large number of these patients suffer from a form of hypothyroidism (low thyroid hormone blood levels) that requires thyroid hormone as replacement therapy. As an endocrinologist (hormone specialist), therefore, I frequently must prescribe thyroid replacement therapy. While the tablets
are small and available in many doses to allow for precise dosing, there are a few helpful hints patients should be aware of to assure they are taking their medication properly and achieving the maximum results from their therapy.
Thyroid hormone therapy is the use of synthetic thyroid hormones to raise abnormally low levels of thyroid hormones. Often used to treat an underactive thyroid that is secreting little or no thyroid hormones, thyroid hormone therapy is usually administered in pill form. The most commonly prescribed thyroid hormone replacement is pure synthetic thyroxine (T4).
Thyroid hormone therapy is generally prescribed when a person's thyroid is not producing enough thyroid hormone naturally (a condition referred to as hypothyroidism). Other reasons for using thyroid hormone therapy may include controling the growth of the enlarged thyroid gland (also called goiter), controling the growth of nodules on the thyroid gland if the history of thyroid cancer (use of thyroid hormone therapy can reduce the risk of recurring tumors), and controling levels of thyroid stimulating hormones (TSH), which may stimulate thyroid cancer
Proper dosage is tailored to each individual patient's needs through careful blood testing. The blood tests reveal levels of thyroid hormones in the blood, as well as thyroid stimulating hormones (TSH) emitted by the pituitary gland. The pituitary gland plays an integral role in the functioning of the thyroid gland. It controls how much thyroid hormone is released by producing TSH that "stimulates" the thyroid. Increased levels of TSH may indicate an underactive thyroid.
Yearly checkups are usually conducted to measure levels of thyroid hormones and TSH. Hypothyroidism can be a progressive disease, requiring dosage increases over time.
Once a stable dose of thyroid replacement has been reached (as indicted by normalization of the thyroid blood tests), this dose may continue for years--if the patient does not take new medications and remains otherwise healthy. A variety of conditions can alter the requirements of thyroid hormone replacement. For example, dosage requirements can decrease with advancing age. A reduction in dosing may also be required in women receiving androgen therapy for breast cancer. Most other conditions require an increase in the dose of thyroid hormone replacement to maintain appropriate blood levels. Many medications can also increase the thyroid hormone replacement needs.
Thyroid hormone replacement is very effective in the vast majority of cases. However, to provide optimal results, it is important to take into account any factors that may influence the effectiveness of replacement therapy. By following these simple suggestions and alerting your physician to any medication changes, you can play an active role in optimizing your thyroid hormone replacement, and help to assure the best therapeutic regimen possible.