Reprinted from Eating Disorders Review
May/June 2001 Volume 12, Number 3
©2001 Gürze Books
Patients with anorexia nervosa (AN) commonly have low triiodo-thyronine (T3) syndrome and blunted and delayed thyrotropin (TSH) response to exogenous thyrotropin-releasing hormone (TRH). Now there is evidence that AN causes diffuse shrinkage of the thyroid gland. According to researchers at Odense University Hospital, Odense, Denmark, such atrophy could hypothetically be part of a vicious cycle that perpetuates anorectic or depressive symptoms (Int J Eat Disord 2001; 29:230).
The Danish researchers used ultrasound to compare 22 patients with anorexia nervosa and 44 age- and sex-matched normal-weight control subjects. Lean body mass was established by dual-energy x-ray absorptiometry. Blood tests included serum T4 levels (normal range: 65-135 nmol/l), determined by radioimmunoassay.
Smaller thyroid glands noted in AN patients
Thyroid volume was highly significantly reduced in the AN patients in comparison to the controls: 9.2 ml versus 17.8 ml. In addition, in the AN patients, thyroid size was not correlated to body mass index or to the amount of lean body mass.
Among the anorexia nervosa patients, 6 women (27%) had nonspecific discrete morphologic changes, including slight-to-moderate diffuse hypoechogenicity, or low reflection of sound, or heterogeneous thyroid echotexture, or an unclear reflection of sound. Thyroid shape was normal in the control group. None of the 6 patients had a family history of thyroid disease and they did not differ from the other patients as to thyroid hormone levels or duration of disease.
Thyroid disorders are clearly associated with affective disturbances and sometimes may persist even after appropriate supplementation. Looking at it another way, abnormalities of the thyroid axis have been noted in euthyroid patients with affective disorders as well as in AN patients. For example, a blunted and delayed TSH response to exogenously administered TRH has been reported in normal-weight patients with depressive illness (Loosen, 1985) and in from 25% to 50% of AN patients.
The authors believe that thyroid atrophy in AN patients is probably secondary to emaciation and low IGF-I levels. Once the process is underway, it could begin a vicious cycle, perpetuating anorectic or depressive symptoms.