Primary hypothyroidism is usually the result of Hashimoto's (autoimmune) thyroiditis, thyroidectomy, or radioactive iodine therapy. Treatment of hypothyroidism with replacement doses of thyroid hormone is usually lifelong. Levothyroxine (LT4; synthetic thyroxine; Synthroid, and others) is the drug of choice.1

In our October 26, 2015 article on drugs for hypothyroidism (Med Lett Drugs Ther 2015; 57:147), we said that levothyroxine should be taken on an empty stomach with a full glass of water 30-60 minutes (60 is preferable) before breakfast. We should have added that taking the drug consistently at bedtime, at least 3 hours after the last meal, is an alternative that some patients may find more convenient.

Primary hypothyroidism is usually the result of Hashimoto's thyroiditis, thyroidectomy, or radioactive iodine therapy. Treatment of hypothyroidism with replacement doses of thyroid hormone is usually lifelong. Levothyroxine is the drug of choice.

Primary hypothyroidism is usually the result of Hashimoto's thyroiditis, thyroidectomy for hyperthyroidism, goiter or cancer, or radioactive iodine therapy for hyperthyroidism.

Hypothyroidism is usually the result of Hashimoto's thyroiditis, thyroidectomy for hyperthyroidism or cancer, or radioactive iodine therapy. Treatment of hypothyroidism with replacement doses of thyroid hormone is usually lifelong. The drug of choice for thyroid replacement therapy is levothyroxine. Liothyronine and dessicated porcine thyroid are also marketed for this indication.

The FDA has determined that 3 generic formulations of levothyroxine are therapeutically equivalent to brand-name formulations. Some brand-name manufacturers have objected, and endocrine organizations have expressed their concern.
See levothyroxine addendum

The media recently reported that the FDA has threatened to withdraw Synthroid from the market, alarming many physicians and patients.