RESUMO
At the end of the 19th century symptoms and signs of hypothyroidism were described in the medical literature. At that time myxedema was a main clinical presentation of the hypothyroid patient. Today, the diagnosis of hypothyroidism is determined mainly by laboratory evaluation with most patients exhibiting only a few clinical signs of thyroid dysfunction. The treatment of hypothyroidism has progressed from partially purified extracts of bovine thyroid gland to an oral administration of synthetic hormone. Since 1981 the only thyroid hormone replacement drug approved by the Israeli Ministry of Health was the Eltroxin brand, made by GlaxoSmithKline. Levothyroxine has a narrow therapeutic range, thus a potential variance exists in the therapeutic efficacy among different levothyroxine preparations. In 2007 the Food and Drugs Administration (FDA) announced that the difference in potency of various levothyroxine brands should not exceed ten percent. In 2007 the GSK Company moved the manufacturing of Eltroxin from Canada to Germany. This resulted in a change of the inert ingredients of the drug. It is of interest to know that since the arrival of the new thyroxine formulation in the Israeli pharmaceutical market there has been a dramatic increase in reports of adverse reactions. The media coverage of adverse effects associated with Eltroxin became widespread in television, newspapers and internet sites. This led to a burden on the healthcare system, manifesting itself by an increase in thyroid blood tests, physician follow-up visits, as well as the importing and distribution of a new brand of thyroxine.
