Variability of TRH test responses in depressed and normal elderly subjects

Thyrotropin releasing hormone (TRH) tests were conducted in 33 elderly patients with Major Depressive Disorder and 99 normal elderly volunteers. A wide range of thyrotropin-stimulating hormone (TSH) responses to TRH injection was revealed. A gender effect was found such that men had significantly diminished TSH responses to TRH relative to women (p = 0.008). However, there were no significant differences noted between depressed patients and normal elderly subjects of either gender. It appears that the wide range of TSH responses to TRH found in normal elderly men and women blurs any measurable differentiation between depressed patients and normal subjects and thereby limits the usefulness of the TRH test in the study of depressive disorder in elderly patients.