Effects of age and diagnosis on thyrotropin response to thyrotropin-releasing hormone in psychiatric patients.

The thyrotropin (thyroid-stimulating hormone; TSH) response to thyrotropin-releasing hormone (TRH) was studied in 64 age-matched healthy volunteers, 44 patients with endogenous depression, and 21 patients with schizophrenia. A significant negative correlation between delta TSH and age was found both in healthy subjects and in depressed patients. We based our comparison on normal ranges for delta TSH calculated from the delta TSH values in the healthy subjects related to age. It was then seen that blunted TSH response to TRH does not occur significantly more often in depression (13.6%) than in healthy controls (4.7%). Blunted TRH test results were also found in a considerable number of severely ill schizophrenic patients (19%). Application of an improved radioimmunoassay revealed a highly significant correlation between TSH values at baseline and after stimulation, and showed decreased baseline TSH levels in subjects with blunted TRH test results.