Background

• Thyroid extracts are derived from animal thyroid tissue. Thyroid extract is a type of glandular nutritional supplementation that refers to dried and ground-up raw animal tissues or extracts of these tissues. Desiccated thyroid, such as the brand Armour® Thyroid, is derived from animal tissues, typically bovine or porcine thyroid. It contains both liothyronine (T3) and levothyroxine (T4).
• Glandulars and other tissue extracts have played roles in traditional medicine since the late 1800s. Glandular therapy originated from the practice of eating the whole gland. Glandulars are thought to improve the function of the specific gland consumed. Early reports (1891) have suggested successful treatment of hypothyroidism with thyroid extracts. This practice originated in Europe and spread quickly to the United States. Desiccated thyroid or thyroid extract is still used by some practitioners, but most practitioners now use synthetic T4 or a combination of synthetic T4 and T3.
• Thyroid hormones increase the rates of growth and metabolism and thereby increase respiratory rate, body temperature, heart rate, reproductive behavior, and energy use.
• Although thyroid extract has been traditionally used to replace patients' normal thyroid activity, limited study does not support the use of thyroid extract for hypothyroidism (underactive thyroid).

References

• Mazer, NA. Interaction of estrogen therapy and thyroid hormone replacement in postmenopausal women. Thyroid 2004;14 Suppl 1:S27-S34.
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• Roberts, CG and Ladenson, PW. Hypothyroidism. Lancet 3-6-2004;363(9411):793-803.
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• Uzzan, B, Campos, J, Cucherat, M, et al. Effects on bone mass of long term treatment with thyroid hormones: a meta-analysis. J Clin Endocrinol Metab 1996;81(12):4278-4289.
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