title: Impact of different cut-off limits of peak GH after GHRH-arginine stimulatory test, single IGF1 measurement, or their combination in identifying adult patients with GH deficiency.
abstract: OBJECTIVE
  To evaluate the impact of different peak GH cut-off limits after GHRH-Arg test, IGF1 measurement, or their combination in identifying patients with GH deficit (GHD).
  
  
  METHODS
  Totally, 894 normal subjects (used for determining IGF1 normative limits) and 302 patients with suspected GHD were included. Different peak GH cut-off limits (used by European (depending on body mass index (BMI)) or North American (4.1 μg/l) Endocrine Societies, by HypoCCs (2.5 μg/l), or with 95% specificity (based on BMI), Method 1, 2, 3, or 4 respectively) and IGF1 were considered.
  
  
  METHODS
  Peak GH after GHRH-Arg and IGF1.
  
  
  RESULTS
  Different peak GH cut-off limits recognized different proportions of GHD (range, 24.8-62.9%). Methods 1 and 2 with high sensitivity recognized a higher proportion (95.5 and 92.5% respectively) of GHD among patients with three (T) pituitary hormone deficits (HD), whereas Method 4 (with high specificity) identified 96.7% normal subjects among those without pituitary HD; on the contrary, Method 4 identified only 75% GHD among patients with THD, whereas Method 1 recognized a high proportion (40%) of GHD among subjects without HD. Of the total patients, 82% with THD and 84.5% without HD were recognized as GHD or normal respectively by IGF1. Among the remaining patients with THD and normal IGF1, 75% was recognized as GHD by Method 1; among patients without HD and abnormal IGF1, 87.5% was identified as normal by Method 4. Overall, combination of IGF1 and Method 1 or Method 4 identified 95.5% GHD among patients with THD and 98.1% normal subjects among those without HD.
  
  
  CONCLUSIONS
  Single peak GH cut-offs have limits to sharply differentiate GHD from normal subjects; IGF1 may be used for selecting patients to be submitted to the GHRH-Arg test; the peak GH cut-off limits to be used for identifying healthy or diseased patients depend mainly on the clinical context.
authors.affiliation: Department of Endocrinology and Metabolism, University of Pisa, Ospedale Cisanello, 56124 Pisa, Italy. fausto.bogazzi@med.unipi.it
authors.forename: Fausto
authors.initials: F
authors.lastname: Bogazzi
authors.forename: Luca
authors.initials: L
authors.lastname: Manetti
authors.forename: Martina
authors.initials: M
authors.lastname: Lombardi
authors.forename: Clara
authors.initials: C
authors.lastname: Giovannetti
authors.forename: Valentina
authors.initials: V
authors.lastname: Raffaelli
authors.forename: Claudio
authors.initials: C
authors.lastname: Urbani
authors.forename: Ilaria
authors.initials: I
authors.lastname: Scattina
authors.forename: Pasquale
authors.initials: P
authors.lastname: Pepe
authors.forename: Aldo
authors.initials: A
authors.lastname: Iannelli
authors.forename: Enio
authors.initials: E
authors.lastname: Martino
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Rossi
mesh_terms: D000172:Acromegaly / Q000097:blood / Q000175:diagnosis; D000328:Adult; D001120:Arginine / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D004393:Dwarfism, Pituitary / Q000097:blood* / Q000175:diagnosis*; D005260:Female; D013007:Growth Hormone-Releasing Hormone / Q000097:blood*; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000378:metabolism*; D008297:Male; D008403:Mass Screening / Q000592:standards; D008875:Middle Aged
chemical_list: D015415:Biomarkers; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine