Endocrine Abstracts

The aim of our study was to investigate de relationship between anthropometric and body composition parameters and thyroid function (measured with TSH and free T4), as well as thyroid volume, in patients with obesity.

Methods: This is a cross-sectional study including patients with obesity consecutively referred to our tertiary endocrine center for diverse pathologies. TSH and free T4 was measured in all patients and thyroid ultrasound was performed by an experienced investigator, to estimate thyroid volume. Whole body DXA scans were available to evaluate total and regional body composition (lean and fat mass). We excluded from our analysis patients with abnormal thyroid function (TSH > 10 or < 0.5 mIU/l).

Results: In our group of 221 patients (147 women) mean BMI was 37.03±7.37 kg/m²and mean age was 51.9± 18.95 years. As expected, TSH positively correlated with BMI (r=0.142, P < 0.05), while free T4 was negatively associated with total lean mass (r=-0.143, P < 0.05), legs lean mass (r=-0.136, P < 0.05) and total fat-free mas (r=-0.169, P < 0.05). Thyroid volume was significantly higher in men (P < 0.01) and correlated with total lean mass (r=0.333, P < 0.001), %fat mass (r=-0.213, P = 0.002), weight (r=0.179, P < 0.05) and height (r=0.225. P < 0.01), but not with BMI. Lean mass remained positively associated with thyroid volume in a multivariate linear regression analysis which also included age, gender and %fat, together explaining about 41% of its variation.

Conclusions: In patients with obesity, lean mass is a factor independently associated with thyroid volume