I will put my opinion regarding the issue.
Usually abnormality in the function of adrenal gland can give rise to Cushing's syndrome or Addison's disease and others.
If you have some of the symptoms like excessive fatigue
, stressed out, craving for salts and sweets, difficulty concentrating, dizziness, extreme sensitivity to the cold, low blood pressure
, delayed recovery from illness, sleep disturbance etc. and doctor do not find other common causes of all the symptoms, then doctor can do tests like cortisol level, ACTH stimulation test to exclude Cushing's syndrome or Addison's disease.
I hope this information helps.
Happy to assist, if you need any clarification.
Please feel free for any follow up query.