The inactivation of thyrotrophin releasing hormone by plasma in thyroid disease.

The inactivation of immunoreactive TRH in vitro by human plasma has been investigated. In a preliminary study, 2.5 ng TRH was destroyed by 50 mul plasma at a mean rate of 1.7%/min in eight subjects. The per cent inactivation of the same amount of TRH at three plasma dose levels was measured after 60 min in seventy unselected patients attending a thyroid clinic. There was no significant difference in the results obtained in those subsequently shown to be euthyroid (forty-three patients), hyperthyroid (eighteen patients) or hypothyroid (nine subjects).