Thyroid Replacement Hormones (cont.)
Eni Williams, PharmD, PhD
Eni Williams, PharmD, PhD
Dr. Eni Williams graduated from Creighton University in 1988 with a B.S. degree in pharmacy and a Doctor of Pharmacy from Howard University in 1994. She also obtained a Ph.D. in Public Policy in 2009 at the University of Maryland, Baltimore County.
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What are the side effects of thyroid replacement hormones?
Thyroid replacement hormones usually are well tolerated. Symptoms that occur during treatment are often due to toxic, elevated levels of thyroid hormones and resulting symptoms from hyperthyroidism. Symptoms may include chest pain, increased heart rate or pulse rate, excessive sweating, heat intolerance, nervousness, headache, insomnia, diarrhea, vomiting, weight loss, and fever. Some women may experience irregular menstrual cycles.
What are some examples of thyroid replacement hormones?
The following is a list of the thyroid replacement hormones that are available in the United States:
For what conditions are thyroid replacement hormones used?
Thyroid replacement hormones are used to treat hypothyroidism (low production of thyroid hormone) and myxedema, a condition that is caused by prolonged hypothyroidism. Thyroid replacement hormones prevent thyroid hormone release from cancerous thyroid nodules and are used therefore to treat thyroid cancers. They also are used to manage thyrotoxicosis, a condition in which there are high levels of thyroid hormones resulting from over-active thyroid glands and too much thyroid hormone. Thyrotoxicosis may progress to hypothyroidism or cause the growth of goiters necessitating the use of thyroid replacement hormones.
Are there any differences among the different types of thyroid replacement hormones?
There is conflicting evidence regarding which hormone replacement therapy should be preferred. The American Association of Clinical Endocrinologists recommends that clinical hypothyroidism is best treated with synthetic T4 levothyroxine (for example levothyroxine and sodium [Synthroid, Levoxyl and Levothroid]). There is variability between the absorption and distribution of generic T4 compared to brand name preparations. Hence it is recommended that patients remain with specific brand names during treatment. There is also variability between generic formulations and brand names of pure T3 (liothyronine [Cytomel, Triostat]), combined T4/T3 formulations (liotrix [Thyrolar]) and thyroid extracts from animal sources (Armour Thyroid, Nature-Throid etc.). Thyroid extracts from animal sources are no longer available in the United States. Emerging information shows that combination of T4/T3 therapy may have some advantages over T4 in cognitive performance and mood but studies are not conclusive.
Medically Reviewed by a Doctor on 3/27/2015
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