The Use and Misuse of Thyroid Hormone*

Abstract

I. Introduction THYROID hormones are frequently prescribed for appropriate and, at times, inappropriate conditions. It has been estimated that 1.2% of the total population in Sweden receives synthetic levothyroxine (L-T4) (1), and 18 million prescriptions for thyroid hormone preparations are filled annually in the United States, corresponding to more than 1% of all medical prescriptions (2). Therefore, it is important to review the various thyroid hormone preparations (Table 1), the therapeutic indications (Table 2), the misuse of thyroid hormone (Table 3), controversial uses of thyroid hormone (Table 4), the thyroid function tests to evaluate the correct treatment dose, and the possible side effects of treatment. Thyroid Hormone Preparations A. Thyroid extract Since 1891, when Murray reported the beneficial effects of sheep thyroid extract given im to a patient with myxedema (3), desiccated thyroid has been used in the treatment of patients with thyroid disease. Thyroid extract is obtained from animal th...