Aims: Our study aimed to investigate the impact of metabolic parameters, specifically insulin level and body-mass index (BMI), on the thyroid gland, considering both morphological and functional aspects. For this purpose, we performed a cross-sectional analysis with euthyroid participants.Methods: One hundred euthyroid adults without thyroid autoimmunity or nodules were included. Thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), fasting insulin levels (FPI), and glucose/insulin values from a 2-hour OGTT were recorded. Anthropometric measures, including BMI and waist circumference (WC), were obtained, and thyroid volume (TV) was measured by ultrasound. The relationship between TV, hormone levels, and metabolic parameters was analyzed.Results: A significant positive relationship was observed between TV and multiple parameters, including BMI, HOMA-IR, HbA1c, FPG, and FPI. Regression modeling identified OGTT 2nd-hour insulin and WC as significant predictors of thyroid volume. Furthermore, FT3 concentrations correlated positively with BMI, WC, HOMA-IR, and FPI measurements.Conclusion: Increased TV appears to be associated with obesity and higher HOMA-IR, whereas FT3 levels show a positive correlation with both. These findings imply a significant interplay between insulin level, adiposity, thyroid gland morphology, and thyroid hormone metabolism.
Bahçecioğlu et al. (Tue,) studied this question.