Thyroid Hormone Replacement Therapy - Tricks of the Trade

Medical Author: Ruchi Mathur, M.D.
Medical Editor: William C. Shiel, Jr., MD, FACP, FACR

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.

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. Below is a list of some common conditions that can alter thyroid hormone replacement requirements:

Decreased Requirements:

  • Aging
  • Androgen therapy in women (breast cancer therapy)
Increased requirements: Medications:

As a patient, it is important you make your doctor aware of any changes in your medications that have been made by other health care professionals. It is recommended that thyroid replacement therapy be taken at the same time each day, usually on an empty stomach. It should be taken by itself, and not with other medications if possible. It is best to avoid taking multivitamins near the time that you take your thyroid hormone replacement, because the cations (calcium, potassium etc.) in the multivitamins impair absorption of the thyroid hormone replacement. For this same reason, you should avoid antacids (which contain other cations such as magnesium and/or aluminum) when taking your thyroid hormone replacement.

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.


Last Editorial Review: 7/2/2002




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