Ectopic ACTH-dependent Cushing’s syndrome due to a pulmonary carcinoid tumor presenting with severe hypokalemia: A case report

Hypokalemia with hypertension and metabolic alkalosis is most often caused by renin–aldosterone disorders, but rarely cortisol excess from ectopic adrenocorticotropic hormone (ACTH) production may be a causative factor. We report the case of a 36-year-old male presenting with persistent severe hypokalemia, in whom systematic evaluation revealed ectopic ACTH-dependent Cushing’s syndrome from a pulmonary carcinoid tumor. The case highlights the importance of considering EAS in refractory hypokalemia to enable early and potentially curative management.