Measurements of thyrotropin-releasing hormone-like material in human peripheral blood by affinity chromatography and radioimmunoassay.

TRH measurements have been carried out in human peripheral blood and rat peripheral and portal blood by RIA in conjunction with affinity chromatography. Human peripheral blood TRH appeared to be identical to synthetic TRH by immunological, chromatographic, and enzymatic criteria. TRH concentrations in normal subjects ranged from 24-138 pg/ml, with a mean of 78 pg/ml. Moreover, TRH concentrations were not altered from normal in either thyrotoxic or hypothyroid subjects. TRH measurements in selected venous compartments in the rat, in conjunction with previously reported kinetic data, suggest that most of the TRH in peripheral blood is derived from nonhypothalamic sources.