Relationship between Thyroid Volume and Iodine, Leptin, and Adiponectin in Obese Women before and after Weight Loss

Abstract

Objective: To investigate whether or not reduction of thyroid volume during weight loss is related to adipocytokines and urinary iodine excretion in obese women. Subjects and Methods: 98 obese and 31 non-obese women consecutively admitted to the endocrinology and metabolism outpatient clinic of the School of Medicine, Akdeniz University were included in the study. Thyroid volume, thyroid function tests, leptin and adiponectin levels, and urinary iodine excretion were measured at baseline and six months after treatment for obesity. Results: Thyroid volume increased in obese women (p = 0.048). After adjustment for body mass index, there were no significant differences in plasma leptin and serum adiponectin levels between obese and non-obese women (p > 0.05). Thyroid volume correlated positively with body mass index (r = 0.48, p = 0.04), leptin (r = 0.1, p = 0.03), and thyroid-stimulating hormone (r = 0.43, p = 0.001) levels, while there was a negative correlation between thyroid volume and urinary iodine (r = –0.38, p = 0.04) and urinary iodine/creatinine ratio (r = –0.25, p = 0.045) in obese women. Changes in body mass index (p = 0.022) and leptin levels (p = 0.039) were the only factors that significantly affected the change of thyroid volume during weight loss. Conclusion: Iodine status may play an important role in increased thyroid volume in obese women; however, iodine status did not seem to exert a significant influence on the changes in thyroid volume. On the other hand, changes in both body mass index and plasma leptin levels seemed to be important for changes in thyroid volume.

Thyroid Volume and Its Relation to Anthropometric Measures in a Healthy Cuban Population

“…Thyroid volume is well known to increase when increasing any anthropometric parameters, such as weight, height, BMI or BSA [4,15,21,28,29]. In our study, the best predictor of thyroid volume was BSA, in line with several other studies [1,5,15,21].…”

Thyroid Function in Human Obesity: Underlying Mechanisms

“…Rotondi et al [87] found morphological changes in thyroid patients with morbid obesity, characterized by the presence of a hypoechogenic pattern on ultrasound in the absence of thyroid abnormalities. In the study conducted by Eray et al [41], the volume of the thyroid was positively correlated with BMI, serum leptin and TSH concentrations, with reduction in the volume of the gland being observed 6 months after weight loss intervention. With regard to the leptin role in chronic inflammation and, consequently, in morphological changes of the thyroid gland, a study with cultured thyroid cells in rats showed that this adipokine, as well as inflammatory cytokines, are capable of inhibiting iodide uptake and expression of the sodium/iodide symporter and thyroglobulin induced by TSH.…”

Thyroid hormone and obesity

“…Following weight loss, FT3 levels decreased and FT4 increased, without significant changes in serum TSH. In a prospective study of 98 premenopausal obese women, thyroid function was studied before and after 6 months of treatment with sibutramine or orlistat [41]. At 6 months, although BMI and leptin levels had decreased significantly, there were no significant changes in TSH, FT3, or FT4 values.…”