Thyroid Hormone Replacement Therapy

What is thyroid hormone 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).

Who needs thyroid hormone therapy?

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:

• to control the growth of the enlarged thyroid gland (also called goiter)

• to control the growth of nodules on the thyroid gland

• if there is a history of thyroid cancer (use of thyroid hormone therapy can reduce the risk of recurring tumors)

How is thyroid hormone therapy dosage determined?

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.

Ensuring proper thyroid hormone dosage:

Proper thyroid hormone dosage is based on blood tests that measure levels of thyroid hormone and thyroid-stimulating hormone (TSH). However, to ensure proper dosage for the duration of the treatment, consider the following recommendations:

• Maintain regular visits to your physician.

• Take your thyroid medication daily.

• Notify your physician of your thyroid hormone treatment before beginning treatment for any other disease, as some adjunctive treatments can affect the dosage of thyroid hormone therapy.

• Let your physician know if you become pregnant.

• Notify your physician of any new symptoms that may arise.

• Notify all healthcare providers of your thyroid condition and medication dosage.

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