The Blunted TSH Response to TRH — What Does It Tell Us? Biological Monitoring During Psychopharmacological Treatment

The past two decades have witnessed an intensive search for a biological substrate in “functional” psychiatric disorders. Psychoneuroendocrinology has offered a fertile field for such investigations, as the perturbations in hormone levels may reflect certain important CNS processes (Langer et al. 1985). Of the several endocrine systems studied, the pituitary-thyroid subsystem has produced certain significant observations which point to applications in clinical practice. Interest in the pituitary-thyroid subsystem seems to have its origins in the reported association between thyroid dysfunction and psychiatric conditions (for review see Loosen and Prange 1984). An impetus to research into the thyroid subsystem applicable to psychiatric disorders was given by the observation that one of the hormones — thyrotropin-releasing hormone (TRH), which regulates the thyroid subsystem — is secreted by hypothalamus (Prange et al. 1987).