OBJECTIVE - Current treatment of benign thyroid is oral levothyroxin by suppression of thyrotropin secretion and so that tumor growth. Although current consensus is taking thyroxin one hour before meal because the PH value of gastrointestinal tract will affect drug absorption, some patient suffered from epigastric discomfort when taking thyroxin with empty stomach, and wish to take it postprandial. However, there is no direct evidence showing if taking thyroxin at different time point significantly affects treatment outcome. Besides, the response to thyroxin therapy differs among people. The purposes of this study are to evaluate the clinical significance of different time points of thyroxine intake and to search factors relating to thyroxin response of benign thyroid tumors.