Isolated Adrenocorticotropin Deficiency With Depressive Symptoms.

Isolated adrenocorticotropin deficiency (IAD) is a rare cause of adrenal insufficiency, often presenting with nonspecific symptoms that can be misattributed to mental disorders or gastrointestinal diseases, particularly in older adults. IAD is characterized by profoundly reduced adrenocorticotropin (ACTH) secretion with preserved secretion of other anterior pituitary hormones. We describe an 81-year-old woman with persistent nausea, vomiting, anorexia, and depressive symptoms that did not respond to standard antidepressant agents. During 2 months of hospitalization, she progressed to impaired consciousness. Routine laboratory tests and magnetic resonance imaging of the pituitary region revealed no abnormalities. Hormonal evaluation showed markedly low levels of cortisol and ACTH. A corticotropin-releasing hormone stimulation test confirmed IAD. The patient had no history of glucocorticoid use, immune checkpoint inhibitors therapy, or other causes of adrenal insufficiency. Intravenous hydrocortisone replacement therapy at 50 mg daily led to a rapid improvement in consciousness and resolution of psychiatric gastrointestinal symptoms. This case emphasizes the importance of considering IAD in older patients presenting with unexplained neuropsychiatric and gastrointestinal symptoms, particularly when standard therapies are ineffective. Early diagnosis and hormone replacement therapy are critical as delayed recognition may lead to life-threatening deterioration, but the condition remains reversible with appropriate management.