title: IGF-I bioactivity might reflect different aspects of quality of life than total IGF-I in GH-deficient patients during GH treatment.
abstract: BACKGROUND
  No relationship has been found between improvement in quality of life (QOL) and total IGF-I during GH therapy.
  
  
  OBJECTIVE
  Our aim was to investigate the relationship between IGF-I bioactivity and QOL in GH-deficient (GHD) patients receiving GH for 12 months.
  
  
  METHODS
  Of 106 GHD patients, 84 on GH treatment discontinued therapy 4 weeks before establishing baseline values and 22 were GH-naive. IGF-I bioactivity was determined by IGF-I kinase receptor activation assay, total IGF-I by immunoassay (Immulite), and QOL by the disease-specific Question on Life Satisfaction Hypopituitarism (QLS-H) module and by the general SF-36 questionnaire (SF-36Q).
  
  
  RESULTS
  IGF-I bioactivity increased after 6 months (-2.5 vs -1.9 SD, P < .001) and did not further increase after 12 months (-1.8 SD, P = .23); total IGF-I increased from -2.3 to -0.9 SD (P < .001) and to -0.6 SD (P = .005), respectively. QLS-H did not change over 12 months (-0.66 ± 0.16 to -0.56 ± 0.17 SD [P = .42] to -0.68 ± 0.17 SD [P = .22]). The mental component summary of the SF-36Q increased from 47.4 (38.7-52.8) to 50.2 (43.1-55.3) (P = .001) and did not further improve (49.4 [42.1-54.1], P = .19); the physical component summary did not change (47.5 [42.0-54.2] vs 47.0 [41.9-55.3], P = .91, vs 48.3 [39.9-55.4], P = .66). After 12 months, IGF-I bioactivity was related to QLS-H (r = 0.28, P = .01); total IGF-I was not (r = 0.10, P = .37). IGF-I bioactivity and total IGF-I were related to PCS (r = 0.35, P = .001; and r = 0.31, P = .003).
  
  
  CONCLUSIONS
  IGF-I bioactivity remained subnormal after GH treatment and was positively related to QLS-H, whereas total IGF-I was not. This suggests that IGF-I bioactivity reflects different aspects of QOL than total IGF-I in GHD patients during GH treatment.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, Erasmus Medical Center, 3015 CE Rotterdam, The Netherlands.
authors.forename: Aimee J
authors.initials: AJ
authors.lastname: Varewijck
authors.forename: Steven W J
authors.initials: SW
authors.lastname: Lamberts
authors.forename: Sebastian J C M M
authors.initials: SJ
authors.lastname: Neggers
authors.forename: Leo J
authors.initials: LJ
authors.lastname: Hofland
authors.forename: Joseph A M J L
authors.initials: JA
authors.lastname: Janssen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D019382:Human Growth Hormone / Q000172:deficiency* / Q000627:therapeutic use; D006801:Humans; D007018:Hypopituitarism / Q000188:drug therapy / Q000378:metabolism* / Q000523:psychology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010549:Personal Satisfaction; D011788:Quality of Life; D011795:Surveys and Questionnaires
chemical_list: D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I