Effect of Supplemental Hydrocortisone During Stress in Prednisolone-induced Adrenal Insufficiency

Inclusion Criteria:

• Age ≥ 50 years
• Women must be postmenopausal (FSH is measured at the screening visit)
• A diagnosis of PMR/GCA, or both conditions combined.
• Treatment with prednisolone ≥12 weeks
• Ongoing prednisolone treatment, with current daily prednisolone dose > 0 mg and ≤5 mg.The dose must have been ≤5 mg for minimum 2 weeks at the time of the screening visit.

Exclusion Criteria:

• Known primary or secondary adrenal insufficiency
• Known Cushing's Syndrome
• Known allergy towards study medication ingredients
• Severe comorbidity: Heart failure (New York Heart Association class IV); Kidneyfailure with an estimated glomerular filtration rate <30 mL/min (Chronic kidneydisease stage 4-5); Liver disease in the form of cirrhosis; Active cancer; Knownsevere immune deficiency; A history of psychiatric disease requiring treatment by apsychiatric department (for affective disorders only if within the last year beforestudy entry)
• Alcohol consumption >21 units per week
• Planned major surgery during the study period at study entry.
• Use of drugs that interfere with cortisol metabolism/measurements: Systemic oestrogentreatment (discontinued < 1 month before inclusion), Treatment with strong CYP3A4inhibitors or inducers, Use of other glucocorticoid formulations (Inhaledcorticosteroids, intraarticular or intramuscular injections, steroid creams Europeansteroid group IV-V used in the genital area. Note: Permitted glucocorticoidformulations: Eye-drops, nasal spray, glucocorticoid creams European steroid groupI-III, and European steroid group IV-V used in the non-genital area only.)
• Inability to provide written informed consent.