What is the optimal treatment for hypothyroidism?

Standard treatment of primary hypothyroidism is with thyroxine, with the ai m of relieving symptoms and bringing the serum TSH (thyroid-stimulating hor mone) concentration to within the reference range. Recent research suggests that in some patients symptoms of hypothyroidism p ersist despite standard thyroxine replacement therapy. The optimal treatmen t of these patients is not known. Adjusting the thyroxine dose until the se rum TSH concentration is in the lower part of the reference range (eg, 0.3- 2.0 mU/L) may be beneficial. Animal studies and a single small clinical trial suggest that a combination of thyroxine and T-3 (triiodothyronine), rather than thyroxine alone, may be required for optimal thyroid replacement therapy. Further research is needed to determine why some patients appear to have a suboptimal response to thyroxine, and whether combined thyroxine/T-3 treatm ent is preferable to thyroxine alone in these patients.