Evidence of diffuse atrophy of the thyroid gland in patients with anorexia nervosa.

Abstract

The altered function of the hypothalamic-pituitary-thyroid axis (HPT) in anorexia nervosa (AN) patients has not been clearly elucidated so far. Low triiodothyronine (T3) syndrome and a blunted and delayed thyrotropin (TSH) response to exogenously administrated thyrotropin-releasing hormone (TRH) are common findings. However, no attention has been paid to thyroid morphology in AN patients. We performed an ultrasonographic (US) evaluation of the thyroid gland in 22 AN patients and in 44 age and sex-matched control subjects. Lean body mass (LBM) was determined by dual-energy X-ray absorptiometry. US-determined thyroid volume was significantly reduced in AN patients (9.2 +/- 0.4 vs. 17.8 +/- 1.2 ml in the controls; M +/- SEM; p < 10(-4)). In healthy subjects, it has previously been established that thyroid volume can be estimated from age and body weight. In the present study, the measured thyroid volume in patients with AN was significantly lower than the predicted thyroid volume (measured: 9.2 +/- 0.4 vs. estimated: 12.2 +/- 0.2 ml; p < 10(-4)). Furthermore, in the AN patients, the thyroid size was not correlated to body mass index (BMI) or LBM. Thyroid volume in AN patients was markedly reduced compared with the control group and with the volume expected from age and body weight or LBM. This indicates thyroid atrophy, which, hypothetically, could be involved in a vicious circle maintaining anorectic or depressive symptomatology.