title: Ectopic growth hormone-releasing hormone secretion by a bronchial carcinoid tumor: clinical experience following tumor resection and long-acting octreotide therapy.
abstract: Acromegaly resulting from the ectopic secretion of growth hormone-releasing hormone (GHRH) is rare. We present a case of acromegaly secondary to proven GHRH-secretion by a bronchial carcinoid tumor in a type 1 diabetic subject and document the clinical course pre- and post-resection of the tumor and of subsequent octreotide therapy. A 54-year-old Caucasian man was referred for evaluation of acromegalic symptoms and significantly increased insulin requirements. He had a history of left lung surgery 20 years prior for hemoptysis. Initial laboratory results indicated acromegaly. Fasting serum growth hormone (GH): 26.1 ng/mL (0-5 ng/mL), insulin-like growth factor 1 (IGF-1): 635 ng/mL (87-283 ng/mL), GH at 60 min post-ingestion of 75 grams of oral glucose during a glucose tolerance test: 8.3 ng/mL (normal <1 ng/mL). Pituitary magnetic resonance imaging (MRI) revealed diffuse pituitary enlargement without adenoma. A 4.4 cm left hilar mass was noted on chest computed tomography (CT) scan. Further evaluation for a suspected GHRH-secreting neuroendocrine tumor was pursued. Plasma GHRH level was elevated: 198 pg/mL (<50 pg/mL). Octreoscan showed radiolabelled-octreotide uptake in the left lung mass and pituitary gland. Surgical resection of the lung mass was performed. Immunohistochemical study of the tumor tissue indicated a neuroendocrine tumor secreting GHRH. Postoperatively, serum GHRH, GH and IGF-1 levels fell precipitously. At 10 months, IGF-1 levels were mildly elevated and 7 months of 10 mg long-acting octreotide therapy (Sandostatin(®) LAR(®)) was trialed. At 20 months, off octreotide, serum IGF-1 levels had normalized, acromegalic features were receding, and the patient's daily insulin requirements had decreased by 57%.
authors.affiliation: Clinical Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Bethesda, MD, USA.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Butler
authors.forename: Craig S
authors.initials: CS
authors.lastname: Cochran
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Merino
authors.forename: Dao M
authors.initials: DM
authors.lastname: Nguyen
authors.forename: David S
authors.initials: DS
authors.lastname: Schrump
authors.forename: Phillip
authors.initials: P
authors.lastname: Gorden
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D001984:Bronchial Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D002276:Carcinoid Tumor / Q000188:drug therapy* / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use*
chemical_list: D018931:Antineoplastic Agents, Hormonal; D013007:Growth Hormone-Releasing Hormone; D015282:Octreotide