TRH stimulation test as a predictor of acute and long-term antidepressant response in major depression

We assessed the prognostic utility of the TRH stimulation test by examining (a) the relationship between pre-treatment delta TSH and acute response to fluoxetine treatment, and (b) the relationship between the change in delta TSH (delta delta TSH value) after repeated TRH testing at 6 weeks of fluoxetine treatment and long-term outcome during maintenance fluoxetine or placebo therapy. 43 MDD patients were studied with sequential TRH tests at 6-week intervals. Fluoxetine 'responders' were defined as patients with a Hamilton Depression Rating Scale score < or = 7 by week 9 of treatment and who remained in remission at least 3 additional weeks. These subjects were then randomized to one of four fluoxetine/placebo treatment groups and long-term outcome assessed. Overall, there was no difference in the mean pre-treatment delta TSH values between acute fluoxetine responders and nonresponders. Moreover, we observed similar delta delta TSH values in patients who maintained long-term remission compared to those who relapsed during maintenance with either fluoxetine or placebo. In contrast to prior reports of an higher delta delta TSH value in long-term remitters, the present observation of similar mean delta delta TSH values patients with long-term remission compared to those who relapsed suggest a limited prognostic utility for the TRH stimulation test in MDD.