Abstract: FR-PO0905
A Surgical Cure for Hypokalemia and Metabolic Alkalosis: Lung Wedge Resection of an Ectopic Adrenocorticotropic Hormone-Producing Carcinoid Tumor
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Case Reports - 1
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid, Electrolytes, and Acid-Base Disorders
- 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- Hassan, Seerat, Baylor University Medical Center, Dallas, Texas, United States
- Wiederkehr, Michael R., Baylor University Medical Center, Dallas, Texas, United States
Introduction
Lung neuroendocrine tumors are rare malignancies whose diagnosis are often delayed and may present with paraneoplastic syndromes. Here we describe a rare case of severe persistent hypokalemia and metabolic alkalosis mediated by ectopic adrenocorticotropic hormone (ACTH) production from a lung carcinoid tumor leading to hypercortisolism which ultimately resolved after lung lobe wedge resection.
Case Description
A 79-year-old woman with a history of hypertension (previously well controlled on hydrochlorothiazide (HCTZ)) presented for severe weakness and fatigue and was found to have severe hypokalemia with a potassium less than 1.5 mEq/L. Initially HCTZ use was thought to be the culprit for potassium wasting. However, she also presented with metabolic alkalosis (pH 7.66, HCO3 46 meq/L) and hypertension with a blood pressure of 186/77 mmHg. Exam showed no classical signs of central obesity or abdominal striae. Potassium normalized after supplementation and amiloride use. However, concurrent workup revealed severely elevated cortisol and ACTH levels at 74.8 ug/dL and 214 pg/mL respectively. High dose dexamethasone failed to suppress morning cortisol suggesting ectopic ACTH production. A subsequent CT scan of the chest revealed a 1.8 cm solid left lower lobe nodule concerning for neoplasm (Image 1). Subsequently, a 1.8 cm pathology sample obtained by thoracoscopic left lower lobe wedge resection revealed a typical lung carcinoid tumor. Immediately post-surgically, she exhibited resolution of hypokalemia and alkalosis, her blood pressure normalized, and levels of cortisol and ACTH returned to the normal range, confirming the surgical cure of paraneoplastic ACTH production by a neuroendocrine tumor.
Discussion
Ectopic ACTH producing tumors are a rare cause of Cushing syndrome leading to excess cortisol production overwhelming 11β-hydroxysteroid dehydrogenase type 2, the enzyme responsible for converting active cortisol into inactive cortisone. Severely elevated cortisol stimulates the mineralocorticoid receptor in the distal nephron leading to salt retention, hypertension, metabolic alkalosis and repletion-resistant hypokalemia. Importantly, these metabolic effects may precede the classic features of Cushing syndrome and delay diagnosis. However, as in our patient, ectopic sources of ACTH production may be amenable to surgical cure with prompt resolution of the syndrome.