A 50-year-old male with treatment-resistant major depressive disorder presents for evaluation. He reports persistent depressed mood, anhedonia, fragmented sleep, difficulty concentrating, and a 20-pound weight loss over six months. Laboratory results show an elevated morning cortisol level and a non-suppression result on the dexamethasone suppression test. The PMHNP considers the role of HPA axis dysregulation in his clinical presentation.