Endocrine Abstracts

Introduction: Dexamethasone induced negative feedback on CRH, ACTH and cortisol secretion is one of the key principles in the diagnostic workup of hypercortisolism. Cortisol secretion has been studied extensively, but changes of other steroids remained apart. Our aim was to establish steroid profile changes in 1 mg dexamethasone test.

Methods: The Steroid profile consisting of 103 steroids and their metabolites from the serum of 9 male and 8 healthy female controls was measured before and in the morning at 0800 hours after 1 mg dexamethasone administered at 1100 hours. Samples were analyzed using GCMS/MS for the measurement of most of the steroids. Only a few were measured by RIA.

Results: Dexamethasone administration suppressed the most the levels of corticosterone (29×), cortisol (20×), 11-OH-androstenedione (12×), 11β-Hydroxy-androsterone (13×), 11β-Hydroxy-etiocholanolone (13×), 11β-Hydroxy-epiandrosterone (6×), 17-Hydroxypregnenolone (5×). Other steroids like DHEA (3×), Androstenedione (2×), Pregnenolone (2×) were suppressed at much lower rate than their 11β-hydroxylated metabolites. As expected, none of the measured steroids increased after dexamethasone.

Conclusions: Inhibition of ACTH secretion leads to a strong suppression of the whole adrenal steroidogenesis including androgen production.

The most prominent changes were observed in corticosterone, cortisol, and interestingly 11-OH-androstenedione and their 5-β/α-reduced metabolites, which all decrease more than 10 times in comparison with the basal levels.

This clearly demonstrates the key role of 11β-hydroxylase being the most influenced enzyme by the adrenocortical axis suppression.