Thyroid stimulating hormone and prolactin responses to thyrotropin releasing hormone in nondepressed alcoholic inpatients

Thyroid stimulating hormone (TSH) and prolactin (PRL) responses to thyrotropin releasing hormone (TRH) stimulation are sometimes blunted in alcoholic subjects; however, the mechanisms involved in these phenomena have not been established. We hypothesized that elevations in free thyroid concentrations might be related to these abnormal responses and then tested that hypothesis in a sample of nondepressed alcoholic inpatients (n = 21). Four alcoholic patients had Δ max TSH responses that were < 7 mIU/1; three had PRL responses at or below 8 μg/1. Baseline TSH was the only significant predictor of peak TSH; however, free thyroxine (FT₄) and baseline TSH both were significant predictors of peak PRL. The average baseline FT₄ concentration in alcoholic patients was significantly higher than that in healthy control subjects (n = 10). Our data, thus, suggest that small elevations of FT₄ play a role in the inhibition of TSH and PRL responses to TRH among nondepressed, abstinent alcoholic patients.