[Adverse reactions and changes in norepinephrine and epinephrine in the plasma after intravenous thyroliberin in...

14 normal volunteers, 23 patients with euthyroid goiter, 9 patients with hypothyroidism and 17 patients with hyperthyroidism were injected with 400 micrograms thyroliberin (thyrotropin releasing hormone, TRH). The documented side effects were the same in all the 4 groups studied. Subjective symptoms such as flushing, nausea, urinary urgency, dizziness and headache in decreasing sequence were mentioned by 86% of subjects. Shortly after thyroliberin injection, a mean increase of 26 +/- 13 mm Hg for systolic and 14 +/- 6 mm Hg for diastolic blood pressure as well as an increased heart rate by 7.2 +/- 6.6 min-1 was demonstrated. Plasma catecholamines were lowered in patients with euthyroid goiter and hyperthyroidism and raised in patients with hypothyroidism, compared with the controls. Thyroliberin administration was associated with an activation of the sympathoadrenal system. The increments in plasma epinephrine and norepinephrine concentrations were proportional to initial values, but were insufficient to affect blood pressure. The mean increase of 28% for plasma epinephrine and 21% for norepinephrine were maximal in the second to the forth minute, where subjective symptoms, blood pressure and heart rate were already decreasing. In view of the rapid onset of the subjective symptoms as well as the chronotropic and the pressor response, thyroliberin may partly exert these effects centrally or directly on the vascular system, independently of catecholamines. Since individual systolic blood pressure increased by as much as 64 mm Hg, caution is advised in selecting patients with risk factors for testing.