Isolated Adrenocorticotropic Hormone Deficiency Associated with Sintilimab in the Treatment of Lung Adenocarcinoma: A Case Report and Literature Review.

Isolated adrenocorticotropic hormone (ACTH) deficiency, a rare condition associated with immune checkpoint inhibitors, can manifest with symptoms such as fatigue, poor appetite, dizziness, hypotension, and hyponatremia. We present a case of a 52-year-old Chinese woman with stage IB lung adenocarcinoma who developed these symptoms after 8 months of treatment with sintilimab. Laboratory tests revealed hyponatremia, low ACTH and cortisol levels, and thyrotoxicosis. Imaging studies showed a Rathke's cleft cyst in the pituitary gland but normal adrenal glands. The patient was diagnosed with isolated ACTH deficiency and thyroid dysfunction and prescribed prednisone as replacement therapy, which improved her symptoms despite persistently low ACTH levels. This case highlights the importance of early diagnosis and treatment of immune checkpoint inhibitor-related endocrine disorders and provides insights into their management to enhance clinical practice and outcomes.