title: Hypokalemia associated with a solitary pulmonary nodule: A case report.
abstract: BACKGROUND
  Differential diagnosis of hypokalemia and adrenocorticotropic hormone (ACTH)-dependent Cushing's syndrome often presents challenging in endocrinology and requires careful clinical, biochemical, radiological, and pathological investigations. Hypokalemia is a common abnormality and systematic approach is required to avoid delays in diagnosis of important underlying causes.
  A 49-year-old woman presented with moderate hypokalemia. Further evaluation showed hypercortisolism due to ectopic ACTH secretion.Chest computed tomography (CT) revealed a peripheral solitary pulmonary nodule. Excision biopsy of the nodule showed carcinoid tumor. After excision biopsy, all of the patient's symptoms improved and electrolytes and ACTH levels also became normal.Carciniod tumors should be considered as a differential diagnosis in patients presenting with hypokalemia and ectopic ACTH syndrome. Carcinoid tumor often present as solitary pulmonary nodule and excision biopsy can be curative.
authors.affiliation: Department of Internal Medicine Endocrine and Metabolism Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Samira
authors.initials: S
authors.lastname: Saeian
authors.forename: Seiyed Mohammad Ali
authors.initials: SMA
authors.lastname: Ghayumi
authors.forename: Mesbah
authors.initials: M
authors.lastname: Shams
mesh_terms: D002276:Carcinoid Tumor / Q000175:diagnosis* / Q000601:surgery; D003480:Cushing Syndrome / Q000175:diagnosis* / Q000628:therapy; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007008:Hypokalemia / Q000175:diagnosis* / Q000628:therapy; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000601:surgery; D008875:Middle Aged; D011013:Pneumonectomy / Q000379:methods; D018570:Risk Assessment; D003074:Solitary Pulmonary Nodule / Q000175:diagnosis* / Q000601:surgery; D016896:Treatment Outcome