The TRH test and urinary MHPG in unipolar depression

Twenty-five men and 26 women with major unipolar depression were evaluated by the TRH test and urinary MHPG excretion. A significant positive correlation between TSH response to TRH and urinary MHPG was found in the men, though not in the women. These findings suggest that at least for depressed men, central norepinephrine deficiency may be the neurobiological substrate of blunted TSH responses to TRH.