Did you know?
One out of every 3500 U.S. newborns has no thyroid gland, necessitating therapy within the first 2 months of life to prevent permanent mental and physical damage.¹

By age 60, impairment of thyroid function affects about 17% of women and 8% of men in North America.²

As many as 25% of patients with hypothyroidism have normal levels of T₃.³
Symptoms of thyroid dysfunction can have a significant impact on behavior such as mental confusion and memory problems.⁴

Hypothyroidism can be associated with depression and its symptoms^5,6:

• decreased interest in daily activities
• concentration difficulties
• sleep disturbances
• reduced sexual interest

Even mild thyroid failure can have harmful effects.⁸

What is Hypothyroidism?
The thyroid is a small, butterfly-shaped gland located in the front of the neck, which produces thyroid hormones, or "chemical messengers," that signal cells throughout the body to increase oxygen use. The two key thyroid hormones are L-triiodothyronine (T₃)—the more biologically active thyroid hormone—and thyroxine (T₄).⁹

Hypothyroidism occurs when there is an inadequate secretion of thyroid hormones, resulting in a slowing down of the body's metabolism.^8,10 While low production of these hormones results in hypothyroidism (an underactive thyroid), high production of these hormones results in hyperthyroidism (an overactive thyroid).^7,10

The goals of thyroid hormone replacement therapy are to normalize thyroid hormone levels and to provide symptomatic relief. Although there are several types of thyroid hormone replacement available, no one type is optimal therapy for everyone. As a result, treatment options may vary from person to person.¹¹

1. Thyroid Foundation of America. The most common problem—Hypothyroidism. Available at: http://www.tsh.org/disorders/hypthyroidism/hypothyroidism.html. Accessed April 5, 2007.
2. Thyroid Foundation of America. The most common problem—Hypothyrodism. Available at: http://www.tsh.org/disorders/hypthyroidism/hypothyroidism.html. Accessed April 5, 2007.
3. Hypothyroidism. In: Berkow R, ed. The Merck Manual of Diagnosis and Therapy. 16th edition. Rahway, NJ: Merck Research Laboratories; 1992:1082-1083.
4. Gavin LA. Thyroid crises. Med Clin North Am. 1991;75:179-193.
5. Gunnarsson T, Sjöberg S, Eriksson M, Nordin C. Depressive symptoms in hypothyroid disorder with some observations on biochemical correlates. Neuropsychobiology. 2001;43(2):70-74.
6. Rack SK, Makela EH. Hypothyroidism and depression: a therapeutic challenge. Ann Pharmacother. 2000;34(10):1142-1145.
7. Klein I, Ojamaa K. Thyroid hormone and the cardiovascular system.
   N Engl J Med. 2001;344(7):501-509.
8. Morocco M, Kloos R. Subclinical hypothyroidism in women: who to treat. Clinical Journal of Women's Health. 2000;1(1):39-45.
9. Bellecy F. Facts from your pharmacist: A handout for patients. A patient's guide to thyroid disease. Pharmacy Times. November 2000:57-58.
10. Endocrinology and Metabolism. In: Isselbacher KJ, Braunwald E, Wilson JD, Martin JB, Fauci AS, Kasper DL, eds. Harrison's Principles of Internal Medicine. 13th ed. New York, NY: McGraw-Hill, Inc.;1994:1940.
11. Data on file, Forest Laboratories, Inc.