DOSCORT is a 2-dose, cross-over study primarily aiming to identify and validate novel biological markers (biomarkers) of glucocorticoid effect in the human body. Patients with Addison´s disease, primary adrenal insufficiency, with life-long glucocorticoid replacement therapy will undergo 2 treatment periods where their usual hydrocortisone treatment will be replaced with betamethasone in physiological and supra physiological doses. Blood, saliva, urine, health related Quality-of-life self-assessment forms, measurements of physical activity and sleep quality will be collected from both treatment periods.

Inclusion Criteria:

1. Males and females at ages 20-65 years
2. Previously diagnosed (e.g. more than 12 months ago) with primary adrenal insufficiency due to autoimmune adrenalitis, i.e. Addison´s disease
3. A stable daily glucocorticoid replacement dose for at least 3 months prior to study entry
4. An oral glucocorticoid replacement dose of 15-30 mg Hydrocortisone total daily dose
5. If needed, a stable fludrocortisone replacement dose for at least 3 months prior to study entry
6. Body mass index (BMI) of 20-35 kg/m2
7. Ability to comply to the protocol procedures and having signed informed consent to participate in the study

Exclusion Criteria:

1. Clinical or laboratory signs of significant cerebral, cardiovascular, respiratory, hepaticobiliary/ pancreatic disease which in the investigators judgement may interfere with the study assessment of completion of the study
2. Clinically significant renal dysfunction with a serum creatinine above 150 mmol/L
3. Pregnant or lactating women
4. Diabetes Mellitus
5. Systemic infections
6. Regular dehydroepiandrosterone (DHEA) medication for the past 4 weeks
7. Any medication with agents which in the investigators judgement might interfere with the study drugs kinetics, including therapies affecting gastro intestinal emptying or motility
8. Alcohol/drug abuse or any other condition associated with poor patient compliance, including expected non-cooperation, as judged by the investigator
9. Hypersensitivity to the active substance or any excipients used in the study drug of choice
10. Any additional underlying disease that may need regular or periodic pharmacological treatment with glucocorticoids during the trail, such as asthma, skin- or eye conditions treated with inhaled or topical glucocorticoids
11. Any additional underlying condition that needs treatment with intramuscular or intra-articular steroid injections during the trial

Double-blinded