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DOI: 10.1055/s-0028-1093930
© Georg Thieme Verlag KG Stuttgart · New York
Reduced Plasma Thyrotropin Response to Thyrotropin Releasing Hormone After Dexamethasone Administration in Normal Subjects
Publication History
Publication Date:
07 January 2009 (online)
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Abstract
In order to elucidate at which level glucocorticoids act in inhibiting thyrotropin (HTSH) secretion in man, 200µgm of synthetic thyrotropin releasing hormone (TRH) were injected intravenously in 8 normal subjects before and after oral administration of dexamethasone, 1.0 mg every 8 hr for 5 consecutive days. After dexamethasone, the mean basal plasma HTSH levels were significantly reduced, as was the plasma HTSH response to TRH: this reduced increase occurred in all subjects. The glucocorticoid did not alter significantly the serum thyroxine and triiodothyronine uptake. The data obtained are compatible with a direct inhibiting action of dexamethasone at pituitary level.
Key words
Hypothalamic-Pituitary-Thyroid System - Thyrotropin-Releasing Hormone - Thyrotropin - Glucocorticoids