Suppression of thyrotropin by morphine in a severely stressed patient.

Opiates suppress TSH in experimental animals but are reported to increase TSH in human subjects. We describe a patient in severe pain treated with morphine, whose previously normal TSH fell to a level usually associated with hyperthyroidism. After returning to a normal concentration, TSH again decreased with morphine administration. This suggests that, in contrast to the stimulation of TSH secretion that has been reported in unstressed experimental subjects, morphine can inhibit TSH secretion during stress in man as it does in experimental animals. This observation is consistent with the known sensitization of opiate receptors by stress. Consideration should be given to the possibility that severe suppression of TSH by opiates in stressed patients may induce clinically significant central hypothyroidism.