title: Is further evaluation for growth hormone (GH) deficiency necessary in fibromyalgia patients with low serum insulin-like growth factor (IGF)-I levels?
abstract: OBJECTIVE
  Fibromyalgia (FM) is characterized by diffuse pain, fatigue, and sleep disturbances; symptoms that resemble the adult growth hormone (GH) deficiency syndrome. Many FM patients have low serum GH levels, with a hypothesized aetiology of dysregulated GH/insulin-like growth factor (IGF)-I axis. The aim of this study was to assess the GH reserve in FM patients with low serum IGF-I levels using the GH-releasing hormone (GHRH)-arginine test.
  
  
  METHODS
  We retrospectively reviewed the GHRH-arginine data of 77 FM patients with low serum IGF-I levels referred to our tertiary unit over a 4-year period.
  
  
  RESULTS
  Of the 77 FM patients, 13 patients (17%) failed the GHRH-arginine test. Further evaluation with pituitary imaging revealed normal pituitary glands (n=7), coincident microadenomas (n=4), empty sella (n=1) and pituitary cyst (n=1), and relevant medical histories such as previous head injury (n=4), Sheehan's syndrome (n=1), and whiplash injury (n=1). In contrast, the remaining 64 patients (83%) that responded to the GHRH-arginine test demonstrated higher peak GH levels compared to age and BMI-matched controls (n=24).
  
  
  CONCLUSIONS
  Our data shows that a subpopulation of FM patients with low serum IGF-I levels will fail the GHRH-arginine test. We, thus, recommend that the GH reserve of these patients should be evaluated further, as GH replacement may potentially improve the symptomatology of those with true GH deficiency. Additionally, the increased GH response rates to GHRH-arginine stimulation in the majority of FM patients with low serum IGF-I levels further supports the hypothesis of a dysregulated GH/IGF-I axis in the pathophysiology of FM.
authors.affiliation: Department of Endocrinology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Mailcode L607, Portland, OR 97239-3098, USA. yuenk@ohsu.edu
authors.forename: Kevin C J
authors.initials: KC
authors.lastname: Yuen
authors.forename: Robert M
authors.initials: RM
authors.lastname: Bennett
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Hryciw
authors.forename: Marie B
authors.initials: MB
authors.lastname: Cook
authors.forename: Sharon A
authors.initials: SA
authors.lastname: Rhoads
authors.forename: David M
authors.initials: DM
authors.lastname: Cook
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D004393:Dwarfism, Pituitary / Q000097:blood / Q000150:complications / Q000175:diagnosis*; D005260:Female; D005356:Fibromyalgia / Q000097:blood* / Q000150:complications; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D010901:Pituitary Function Tests; D012189:Retrospective Studies
chemical_list: D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone