title: Decrease of Serum IGF-I following Transsphenoidal Pituitary Surgery for Acromegaly.
abstract: BACKGROUND
  In the immediate postoperative period following resection of growth hormone (GH)-secreting pituitary tumors, serum concentrations of GH have limited ability to predict remission of acromegaly. Since many actions of GH actions are mediated by insulin-like growth factor-1 (IGF-I), we aimed to determine the rates of fall of IGF-I during 72 h after surgical resection of pituitary tumors.
  
  
  METHODS
  We studied patients who were undergoing pituitary surgery for acromegaly. IGF-I was measured by LC-MS and GH by immunoassay. Remission was defined by the combination of serum GH <0.4 ng/mL during oral glucose tolerance testing performed 8 weeks after the surgical procedure and normal IGF-I at ≥8 weeks.
  
  
  RESULTS
  During the first 72 h after surgery, the mean (SD) rate of decline of IGF-I was 185 (61) ng/mL per 24 h in those who achieved remission (n = 23), with a mean (SD) apparent half-life of 55 (19) h. IGF-I had decreased to <65% of the preoperative IGF-I on postoperative day 2 in 20 of 23 remission patients (87%) vs none of 5 patients who did not achieve remission. GH was <2.7 ng/mL on day 2 in 21 of 23 remission patients (91%), but in none of the nonremission patients. The combination of IGF-I and GH on day 2 separated the remission and nonremission groups of patients.
  
  
  CONCLUSIONS
  Rapid decline of serum IGF-I during the immediate postoperative period warrants further study as an analytically independent adjunct to GH measurement for early prediction of biochemical remission of acromegaly.
authors.affiliation: Division of Laboratory Medicine, Department of Pathology, my7m@virginia.edu.
authors.forename: Min
authors.initials: M
authors.lastname: Yu
authors.affiliation: Division of Laboratory Medicine, Department of Pathology.
authors.forename: David E
authors.initials: DE
authors.lastname: Bruns
authors.affiliation: Department of Neurological Surgery, and.
authors.forename: John A
authors.initials: JA
authors.lastname: Jane
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine and Health System, Charlottesville, VA.
authors.forename: Ralf M
authors.initials: RM
authors.lastname: Nass
authors.affiliation: Department of Neurological Surgery, and.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Oldfield
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine and Health System, Charlottesville, VA.
authors.forename: Mary Lee
authors.initials: ML
authors.lastname: Vance
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia School of Medicine and Health System, Charlottesville, VA.
authors.forename: Michael O
authors.initials: MO
authors.lastname: Thorner
mesh_terms: D000172:Acromegaly / Q000097:blood / Q000378:metabolism / Q000601:surgery*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism; D008297:Male; D010911:Pituitary Neoplasms / Q000097:blood / Q000378:metabolism / Q000601:surgery*
chemical_list: D007334:Insulin-Like Growth Factor I