ALTERATIONS IN THYROID-HORMONES AND THYROTROPIN (TSH) IN MORBIDLY OBESE PATIENTS BEFORE AND AFTER VERTICAL GASTROPLASTY

Background: Published results of studies of thyroid function in obesit y and after weight loss have differed. Methods: The circulating concen trations of thyroid hormones and TSH were studied in 30 consecutive, e uthyroid morbidly obese patients before and after weight loss from ver tical gastroplasty, with the aim to determine the relation between bod y weight loss and pituitary-thyroid axis function. Serum TSH, free T3 (FT3) and free T4 (FT4) were measured before operation and repeated 6 and 18 months postoperatively. Results: A significant increase, but wi thin normal levels, in FT3 value at 6 and, mainly, at 18 months after gastroplasty was observed (p = 0.002). The FT4 value was slightly incr eased at the same time and serum TSH was found to be significantly dec reased (p = 0.03 and p = 0.01 respectively). The relative increase in FT4 was negatively correlated with excess body weight and Body Mass In dex reduction, This correlation was only moderate with values ranging from r 0.34 to r = 0.47. Conclusions: Although there were statisticall y significant differences in thyroid function tests before and after l oss of weight, these were not biologically significant. The hypophysea l/thyroid axis remains always active and contributes to body weight ho meostasis and its regulation.