In Study 1, we manipulated endogenous cortisol levels using a speech stressor following encoding.
Metyrapone suppressed endogenous cortisol release to circadian nadir-equivalent levels at the time of retrieval testing.
Comparison groups included cardiac surgical patients who received etomidate to lower endogenous cortisol during surgery and healthy volunteers who received methylprednisolone only.
Chronocort, a multiparticulate formulation with sustained-release properties replaces endogenous cortisol in a near-physiologic manner and fully restores the end of night cortisol peak.
The plasma concentrations of prednisone, its main metabolite prednisolone, and endogenous cortisol were measured by HPLC at selected times during 8-h periods starting at 7 30 a.m.
Shortly after ICU admission (T0), there were high levels of cortisol present in GC-treated patients as compared to healthy subjects (p = 0.01), reflecting both endogenous cortisol and hydrocortisone (Fig. 4).
With the recent observation of substantial reduction in cortisol metabolism during critical illness [6], it is more likely that an excessively high concentration of endogenous cortisol and administered hydrocortisone caused decreased GR binding capacity.
Results on bovine urine samples collected on two animals before and after dexamethasone administration showed important differences regarding the proportion of total conjugated forms between endogenous cortisol, endogenous tetrahydrocortisol, and exogenous dexamethasone.
To further clarify the influence of MR in HPA activity we studied 10 healthy men during the circadian nadir of HPA activity (14 00 to 21 00) after pre-treatment with 3 g metyrapone to minimize the impact of basal endogenous cortisol secretion.
In comparison with the controls, the hypothyroid boy showed a marked increase in the total AUC of prednisone (3360 μg h/L versus 215 ± 83 μg h/L) and prednisolone (4040 μg h/L versus 724 ± 77 μg h/L), and an altered pattern of endogenous cortisol, which is known to be impaired in hypothyroid subjects.
To characterize the role of mineralocorticoid (MR) in regulation of HPA axis activity during nocturnal sleep and involvement in sleep architecture, we investigated sleep endocrine effects of the MR agonist fludrocortisone in healthy men after pretreatment with metyrapone to minimize the impact of endogenous cortisol.
