Glucocorticoid treatment:clinical consequences and effects on the HPA axis

This thesis comprehends a wide variety of angles on the hypothalamic-pituitary-adrenal (HPA) axis, our central stress response system. The studies described evaluate the residual function of the HPA axis when this has been lost due to disease or when the patient receives medication that suppresses the function of the HPA axis.Cortisol is a vital hormone and is of great importance in almost all bodily processes. Cortisol is produced by the adrenal gland. The adrenal gland is controlled by hormones produced in the hypothalamus and pituitary gland. Once cortisol is in the bloodstream, it has effects on a variety of tissues. For example, cortisol plays a role in regulating blood pressure or inhibiting immune function. Cortisol can be inactivated by an enzyme. Inactivated cortisol is called cortisone. Cortisol and cortisone are metabolized in the liver. Cortisol, cortisone and the metabolites are excreted in urine. The amount of cortisol, cortisone and metabolites in urine is a good reflection of the HPA axis activity. Cortisol, cortisone and metabolites are therefore the main outcome parameters in this thesis. In this thesis, the residual function of the HPA axis was investigated in patients with primary and secondary adrenal insufficiency, in patients who chronically use prednisolone and thereby suppress their HPA axis, and in patients who are tapering their prednisolone, thereby gradually recovering their own HPA axis activity. Finally, this thesis describes the CORE study, where we investigate the effects of prednisolone and dexamethasone in healthy subjects

Susceptibility to Adrenal Crisis Is Associated With Differences in Cortisol Excretion in Patients With Secondary Adrenal Insufficiency

Objective: To compare cortisol pharmacokinetics and pharmacodynamics mapped through several glucocorticoid sensitive pathways in patients on hydrocortisone substitution with or without an adrenal crisis. Design: A post-hoc analysis of a previously conducted randomized controlled trial in patients with secondary adrenal insufficiency examining the effects of 2 weight-adjusted hydrocortisone doses. Methods: Comparisons were primarily made on a hydrocortisone dose of 0.2-0.3 mg/kg/day for plasma cortisol and cortisone, 24-hour urinary steroid profile, the glucocorticoid sensitive tryptophan-kynurenine pathway, the renin-angiotensin-aldosterone system and aspects of quality of life. Variables of interest were also analyzed on the hydrocortisone dose of 0.4-0.6 mg/kg/day. Results: Out of 52 patients, 9 (17%) experienced at least one adrenal crisis (AC+ group) and 43 did not develop an adrenal crisis (AC- group) during an observation period of 10 years. 24-hour urinary excretion of cortisol and cortisone were lower in the AC+ group (0.05 [IQR 0.03; 0.05] vs. 0.09 [0.05; 0.12] µmol/24h, P=0.01and 0.13 [0.10; 0.23] vs. 0.24 [0.19; 0.38] µmol/24h, P=0.04, respectively). No differences in pharmacokinetics of cortisol were observed. Kynurenine concentrations were higher in the AC+ group (2.64 [2.43; 3.28] vs. 2.23 [1.82; 2.38] µmol/L, P=0.03) as was general fatigue (Z-scores 1.02 [-0.11; 1.42] vs. -0.16 [- 0.80; 0.28], P=0.04). On the higher hydrocortisone dose urinary excretion of cortisol and cortisone was still significantly lower between the AC- and AC + group. The differences in glucocorticoid sensitive variables disappeared. Conclusion: Patients susceptible to an adrenal crisis demonstrated differences in cortisol and cortisone excretion as well as in pharmacodynamics when compared to patients who did not experience an adrenal crisis, suggesting a biological predisposition in certain patients for the development of an adrenal crisis

Residual endogenous corticosteroid production in patients with adrenal insufficiency

Objective This study aimed at comparing precursors of endogenous corticosteroid production in patients with primary adrenal insufficiency and in secondary adrenal insufficiency. Design Twenty patients with primary adrenal insufficiency and matched controls and 19 patients with secondary adrenal insufficiency participated in this ancillary analysis of two different studies. Patients and measurements Patients with primary adrenal insufficiency were on stable hydrocortisone and fludrocortisone therapy. Patients with secondary adrenal insufficiency received two different doses of hydrocortisone in a randomized crossover study. Main outcome measures were concentrations of precursors of cortisol and aldosterone measured by LC-MS/MS Results Compared to controls, progressively lower concentrations of the glucocorticoid precursors 11-deoxycortisol, 11-deoxycorticosterone and corticosterone concentrations were found in patients with secondary adrenal insufficiency on lower hydrocortisone dose, secondary adrenal insufficiency on higher hydrocortisone dose and primary adrenal insufficiency, respectively. Half of the primary adrenal insufficient patients showed evidence of residual endogenous cortisol or aldosterone synthesis, as determined by quantifiable 11-deoxycortisol, 11-deoxycorticosterone and corticosterone conce ntrations. In secondary adrenal insufficient patients with higher endogenous cortisol production, as indicated by 11-deoxycortisol concentrations above the median, no increased cortisol exposure was observed both by plasma pharmacokinetic parameters and 24-hour free cortisol excretion in urine. Conclusions Adrenal corticosteroid production is likely to continue during treatment in a considerable percentage of patients with both primary and secondary adrenal insufficiency. In patients with secondary adrenal insufficiency, this synthesis appears to be sensitive to the dose of hydrocortisone. However, the residual corticosteroid concentrations were quantitatively low and its clinical significance remains therefore to be determined

Rationale and design of the CORE (COrticosteroids REvised) study:protocol

Introduction Corticosteroids are an important pillar in many anti-inflammatory and immunosuppressive treatment regimens and are available in natural and synthetic forms, which are considered equipotent if clinical bioequivalence data are used. Current clinical bioequivalence data are however based on animal studies or studies with subjective endpoints. Furthermore, advancement in steroid physiology with regard to metabolism, intracellular handling and receptor activation have not yet been incorporated. Therefore, this study aims to re-examine the clinical bioequivalence and dose effects of the most widely used synthetic corticosteroids, prednisolone and dexamethasone. Methods and analysis In this double-blind, randomised cross-over clinical trial, 24 healthy male and female volunteers aged 18-75 years, will be included. All volunteers will randomly receive either first a daily dose of 7.5 mg prednisolone for 1 week, immediately followed by a daily dose of 30 mg prednisolone for 1 week, or first a presumed clinical bioequivalent dose of 1.125 mg dexamethasone per day, immediately followed by 4.5 mg of dexamethasone per day for 1 week. After a wash-out period of 4-8 weeks, the other treatment will be applied. The primary study endpoint is the difference in free cortisol excretion in 24 hours urine. Secondary endpoints will include differences in immunological parameters, blood pressure and metabolic measurements. Ethics and dissemination This study has been approved by the Medical Ethics Committee of the University Medical Center Groningen (METC 2020.398). The results of this study will be submitted for publication in peer-reviewed journals