Morbid obesity in women is associated to a lower prevalence of thyroid nodules

Few studies have recently showed functional and morphological changes of the thyroid gland in relation to obesity. To our knowledge, no data are available about the prevalence of thyroid nodules in female obese patients. The aim of this study was to investigate the prevalence of thyroid nodules in morbidly obese women.

One hundred eight consecutive female obese patients were selected from those referred to our medical and surgery outpatients providing that following criteria were satisfied: (1) affected by morbid obesity (body mass index (BMI) >40 kg/m(2)); (2) no previous diagnosis of thyroid disease; (3) biochemically proven euthyroid state at the time of recruitment. Ninety-seven control subjects, constituted by normo-weight and/or slightly overweight (BMI ≤ 30 kg/m(2)) women, should satisfy the above criteria 2 and 3. All the subjects were submitted to ultrasound investigation.

The two groups of patients displayed no differences for age and fT4 levels. Obese patients clearly showed a lower prevalence of thyroid nodules [odds ratio 0.294, 95% confidence interval 0.206-0.382]. A single nodule was found in 23% of obese patients as compared to 65% of control subjects (p < 0.0001). No difference for age (year) was found between obese and non-obese subjects with nodules (40.5 ± 8.2 vs. 44.2 ± 8.9, respectively, p = 0.07).

Our data clearly show a significantly lower prevalence of thyroid nodules in morbidly obese patients. Further studies are needed to confirm and to understand this first observation.