The DST and TRH test in bulimia nervosa.

Abnormal neuroendocrine responses have been found in depression and eating disorders. It remains unclear whether these reflect an underlying shared biology or epiphenomena. To evaluate this further, we conducted the 1 mg DST and the TSH response to 500 micrograms i.v. TRH in normal-weight bulimics and controls. Bulimics (n = 18) demonstrated significantly more DST non-suppression (45%) than controls (18%; n = 20). In the bulimic group, non-suppressors were significantly thinner than suppressors, but did not differ from them on any measure of depression. Bulimics (n = 19) and controls (n = 12) responded similarly without blunting on the TSH response to TRH. These data suggest that DST non-suppression may be related to non-specific variables such as weight. Bulimics do not demonstrate TSH blunting as found in some depressed patients. These tests do not support evidence for a biological link between these disorders.