title: Reappraisal of serum insulin-like growth factor-I (IGF-1) measurement in the detection of isolated and combined growth hormone deficiency (GHD) during the transition period.
abstract: OBJECTIVE
  To evaluate the accuracy of serum IGF-1 in the detection of isolated (IGHD) or combined growth hormone deficiency (CGHD) at the transition phase.
  
  
  METHODS
  Forty nine patients with GHD during childhood [16 with IGHD (10 men) and 33 with CGHD (24 men); age 23.2 ± 3.5 yrs.] were submitted to an insulin tolerance test (ITT) with a GH peak < 5 µg/L used for the diagnosis of GHD at the transition phase. Pituitary function and IGF-1 measurements were evaluated in the basal sample of the ITT. Transition patients were reclassified as GH-sufficient (SGH; n = 12), IGHD (n = 7), or CGHD (n = 30).
  
  
  RESULTS
  Five (31%) patients with IGHD and 32 (97%) with CGHD at childhood persisted with GHD at retesting. One patient with IGHD was reclassified as CGHD, whereas 3 patients with CGHD were reclassified as IGHD. Mean GH peak was 0.2 ± 0.3 µg/L in the CGHD, 1.3 ± 1.5 µg/L in the IGHD, and 18.1 ± 13.1 µg/L in the SGH group. Serum IGF-1 level was significantly higher in the SGH (272 ± 107 ng/mL) compared to IGHD (100.2 ± 110) and CGHD (48.7 ± 32.8) (p < 0.01). All patients reclassified as CGHD, 86% reclassified as IGHD, and 8.3% reclassified as SGH had low IGF-1 level, resulting in 97.3% sensitivity and 91.6% specificity in the detection of GHD at the transition period; the cutoff value of 110 ng/mL showed 94.5% sensitivity and 100% specificity. Mean IGF-1 values did not differ in IGHD or CGHD associated with one, two, three, or four additional pituitary deficiencies.
  
  
  CONCLUSIONS
  IGF-1 measurement is accurate to replace ITT as initial diagnostic test for IGHD and CGHD detection at the transition phase.
authors.forename: Cesar L
authors.initials: CL
authors.lastname: Boguszewski
authors.forename: Claudio Silva de
authors.initials: CS
authors.lastname: Lacerda
authors.forename: Luiz de
authors.initials: Ld
authors.lastname: Lacerda Filho
authors.forename: Julienne A R de
authors.initials: JA
authors.lastname: Carvalho
authors.forename: Margaret C S
authors.initials: MC
authors.lastname: Boguszewski
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D003430:Cross-Sectional Studies; D005260:Female; D019382:Human Growth Hormone / Q000097:blood / Q000172:deficiency*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D010900:Pituitary Diseases / Q000097:blood / Q000175:diagnosis*; D010901:Pituitary Function Tests; D011237:Predictive Value of Tests; D012016:Reference Values; D012189:Retrospective Studies; D060305:Transition to Adult Care; D055815:Young Adult
chemical_list: D007328:Insulin; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I