A positive association between thyrotropin (TSH) secretion and body-mass index (BMI) was previously reported. There are many studies concerning thyroid function in obesity, and some of them describe higher TSH levels in obese subjects.
Evaluation of the hypothyroidism prevalence in a sample of obese women in their first obesity appointment at Hospital São João.
Anthropometric variables and serum levels of TSH, free triiodothyronine (FT3) and free thyroxine (FT4) were evaluated. They were asked if they were undergoing levothyroxine (LT4) replacement therapy. TSH values between 0.35 and 4.94 ng/dl were consider euthyroidism.
A sample of 257 women having a mean age of 40.9±11.2 years old and a mean BMI of 44.6±7.1 kg/m2 was evaluated. We found a primary hypothyroidism prevalence of 13.2%. The prevalence of diagnosed hypothyroidism undergoing levothyroxine replacement therapy was 5.8% (i.e. 15 patients). From these 5.8%, 86.7% were well-controlled, while 13.3% maintained high levels of TSH under therapy. In the remaining 94.2% (i.e. 242 patients), a prevalence of 7% hypothyroidism, 92.6% euthyroidism and 0.4% hyperthyroidism was found. From the above-mentioned 7% of patients with hypothyroidism, a prevalence of subclinical hypothyroidism was found to be 68.4%.
In the same sample, the mean age of patients with hypothyroidism was 39.3±11.6 years old with a mean BMI of 47.9±11.6 kg/m2, and a mean waist circumference of 128.4±18 cm, while those having euthyroidism revealed a mean age of 41.1±11.1 years old, a mean BMI of 44.3±6.8 kg/m2 and a mean waist circumference of 120.6±13.4 cm. The only patient with hyperthyroidism was 20 years old and revealed a BMI of 60.2 kg/m2.
From this study, the occurrence of a low hypothyroidism prevalence in the analysed sample could be observed. Furthermore, the analysed female patients with hypothyroidism revealed higher BMI and waist circumference and a lower age average than those having normothyroidism.
03 - 07 May 2008
European Society of Endocrinology