Effect of Cortisol on Physical Exertion in Patients With Primary Adrenal

Addison's disease occurs when more than 90% of the adrenal cortex is destroyed. Cortisol levels in serum vary throughout the day. In addition to the daily need, cortisol increases in response to all forms of stress including intercurrent illness. The Addison patient must in such situations increase replacement doses 2 to 3-fold. While it is broad agreement on this procedure based on clinical experience and empirical data, it is controversial as to whether there is a need to increase the dose by less stressful events and tasks, such as average to vigorous physical activity and mental stress. In any event, many patients report that they benefit from stress doses not only in order to increase performance, but also to reduce post-exertion fatigue.

Using a combination of oxygen uptake measurements under controlled exercise and assay of hormones and metabolites, we aim to test whether extra doses of hydrocortisone can increase physical capacity and reduce post-exertion fatigue. Each patient perform two tests, one with and one without hydrocortisone in randomised order. The controls perform one test. The patients will be assigned a participation number and randomised to any of two treatment sequences (A-B or B-A) by pharmacy. All exercise tests will be performed 3-5 hours after intake of morning medication, after an overnight fast (water permitted). Patients will be instructed to avoid caffeinated food and drink, alcohol, strenuous exercise and starvation for at least 24h before each exercise session. Patients will be instructed to avoid smoking, brush teeth one hour before exercise testing.

One hour before each test, subjects drink one teaspoon of water per kilogram body weight to provide adequate hydration. Stress-dose or placebo will be taken 60 min before start. Also at this time, an indwelling line will be placed in the forearm of each subject that blood and saliva can be drawn before, directly after exercise, then 15 or 30 min after termination of exercise. Patients fill out the questionnaire about quality of life after each exercise.

Patient's daily glycemic profile will be followed up by continuous glucose monitoring systems for 24 hours before, during and for 24 hours after exercise. Patients will be educated in using the sensor and calibration with blood glucose self-measurements three to four times per day. Calibration of the sensor will be performed according to the protocol established. At the completion of the measuring period, the system will be returned, and the data will be downloaded to determine glucose patterns. This device will be applied to the abdomen of each subject, 24 h before each exercise session, calibrated as recommended (before operation and 2-3 additional times/day, 6 h apart over the 24 h of the study) and removed 24 h after the exercise session.

The patient's movements will be followed for 24 hour by Actigraph after each test. The test is repeated after 1 week with the opposite treatment option.