Levothyroxine Treatment in Thyroid Benign Nodular Goiter

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.

RESEARCH DESIGN AND METHODS - We will include patients who have benign thyroid tumors diagnosed with fine needle aspiration cytology and have normal thyroid function into our study. After informed consent, patients will be randomly assigned into two groups. Patients in the first group will take thyroxin one hour before breakfast until thyrotropin level stabilized between 0.5 and 1.0 mU/L for 3 months. Then thyroxin will be discontinued. Patients will restart thyroxin therapy three months later but after breakfast. Patients in another group will take thyroxin postprandial, discontinue thyroxin and then one hour before breakfast. Questionnaire interviews about diet and life style, blood samples and fine needle aspiration cytology samples will be obtained. Changes of thyroid nodules will be evaluated with thyroid echo.

STATISTIC ANALYSIS - Descriptive data will be described as means and SDs for continuous variables, and analysis of variance and Chi-square tests were used for assessing the significances. A p-value below 0.05 was considered significant.

Keywords: benign thyroid tumor, thyroxin, preprandial, postprandial.