Relationship between mood and TSH response to TRH stimulation in bipolar affective disorder

Moderate to severe depression and mania are associated with a reduced thyroid stimulating hormone (TSH) response to TSH releasing hormone (TRH). Continued reduction of this response after clinical recovery seems indicative of early relapse. The aim of the present study was to test the relationship between mild changes in mood and the TSH response to TRH stimulation in patients with bipolar affective disorder. Nineteen outpatients with bipolar affective disorder were followed prospectively for three years. Every third month, mood symptoms were rated using the 17-item Hamilton Depression Rating Scale (HAMD-17) and the Bech-Rafaelsen Mania Scale (BRMS). A TRH test was performed in connection with each rating session (IV injection of 200 microg TRH), and serum TSH was measured at 0, 20, and 60 min. The maximum TSH response (D-max TSH) and the temporal change in D-max TSH between succeeding rating sessions (DD-max TSH) were determined. Psychometric rating and TRH data were obtained for a total of 198 examinations. The temporal change in mood symptom rating score was negatively correlated with the temporal change in D-max TSH, thus suggesting that increasing severity of mood symptoms was related to a reduced TSH response to TRH stimulation. The temporal change in TSH response to TRH stimulation correlated with the actual score on an overall index of symptom severity. In conclusion, milder fluctuations in mood in bipolar affective disorder seem to correlate with the TSH response to TRH stimulation: Increasing severity of mood symptoms seems to be associated with reduced TSH response.