title: Severe muscle weakness due to hypokalemia as a manifestation of small-cell carcinoma.
abstract: We describe the case of a 56-year-old man with severe muscle weakness due to heavy hypokalemia (serum potassium 1.44 mmol/l) associated with inappropriate kaliuria and alkalemia. Subsequent investigation revealed the presence of ectopic ACTH hypersecretion due to a small-cell lung carcinoma. A significant clinical/laboratory improvement was achieved following chemotherapy-induced regression of the primary tumor. The profound hypokalemia was probably the result of cortisol hypersecretion, which in concert with the ACTH-induced decreased 11beta-hydroxysteroid dehydrogenase activity can exhibit an increased mineralocorticoid activity. In addition, other ACTH-dependent mineralocorticoids may play a contributory role in the development of severe hypokalemia.
authors.affiliation: Department of Internal Medicine, University of Ioannina Medical School, Ioannina, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Konstantinidis
authors.forename: M
authors.initials: M
authors.lastname: Elisaf
authors.forename: K
authors.initials: K
authors.lastname: Panteli
authors.forename: S
authors.initials: S
authors.lastname: Constantopoulos
mesh_terms: D000182:ACTH Syndrome, Ectopic / Q000209:etiology; D000970:Antineoplastic Agents / Q000627:therapeutic use; D016190:Carboplatin / Q000627:therapeutic use; D018288:Carcinoma, Small Cell / Q000150:complications* / Q000188:drug therapy; D005047:Etoposide / Q000627:therapeutic use; D006801:Humans; D007008:Hypokalemia / Q000209:etiology*; D008175:Lung Neoplasms / Q000150:complications* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D018908:Muscle Weakness / Q000209:etiology*
chemical_list: D000970:Antineoplastic Agents; D005047:Etoposide; D016190:Carboplatin