Thyroid hormone therapy. What, when, and how much.

Hypothyroidism is the condition most commonly treated with exogenous thyroid hormone. The goal of therapy is to normalize levels of serum thyrotropin (thyroid-stimulating hormone), which should be monitored by a high-sensitivity test. Adjustments in optimal dose may be necessary for a number of physiologic reasons (eg, decreased gastrointestinal absorption, pregnancy). Thyroid hormone therapy is also appropriate after surgery for thyroid cancer and for patients with goiter or benign thyroid nodules. In the absence of hypothyroidism, such treatment should not be used for obesity, fatigue, irregular menses, or infertility.