Idiopathic combined adrenocorticotropin and growth hormone deficiency mimicking chronic fatigue syndrome

A 42-year-old man who had suffered from severe fatigue for 5 years was diagnosed as having chronic fatigue syndrome (CFS) and fibromyalgia. Endocrinological workup using combined anterior pituitary function tests showed that the patient had adrenocorticotropin hormone (ACTH) deficiency, with a normal pituitary MRI. Treatment with a physiologic dose of oral hydrocortisone replacement physically ameliorated his general fatigue. A secondary workup using a growth hormone-releasing peptide-2 test revealed that he also had growth hormone (GH) deficiency, and GH replacement therapy was started. His muscle pain and depression were improved by the therapy. Here, we present a rare case of combined deficiency of ACTH and GH in a middle-aged man with severe general fatigue. This case report aims to raise awareness of combined deficiency of ACTH and GH as a differential diagnosis of CFS and its mimics.