title: Responses to GHRH plus arginine test are more concordant with IGF-I circulating levels than responses to arginine and clonidine provocative tests.
abstract: OBJECTIVE
  Although pharmacological GH stimulation tests are still considered the gold standard for GH deficiency (GHD) diagnosis, they are burdened by poor specificity. The majority of children diagnosed as having GHD show normal GH responses when re-tested at the end of growth, thus questioning the initial diagnosis. We evaluated the concordance between IGF-I levels and GH responses to provocative tests.
  
  
  METHODS
  We analyzed 105 GHRH plus arginine tests, 79 arginine tests, and 124 clonidine tests performed in 192 short children. IGF-I levels ≤-2SD score (SDS) were considered suggestive for high likelihood of GHD. The percentage of positive and negative results for each test was determined and compared with IGF-I levels, clinical follow-up and response to therapy.
  
  
  RESULTS
  In children with IGF-I>-2SDS the arginine test showed a concordance rate of 6.9%, the clonidine test of 28.6%, and GHRH plus arginine test of 70%. In children with IGF-I≤-2SDS the concordance was 96.1%, 85.7%, and 46.4%, respectively. The overall concordance was 66.7% for GHRH plus arginine, 42.7% for clonidine, and 27.8% for arginine tests.
  
  
  CONCLUSIONS
  Our results suggest that GHRH plus arginine test provides the best concordance with the assessment of IGF-I levels thus suggesting that the combination of the two procedures may significantly reduce the need of a second provocative test.
authors: Rina Balducci Center of Pediatric Endocrinology, Tor Vergata University, Rome, Italy. claudiogiacomozzi@fastwebnet.it
authors: C
authors: C
authors: Giacomozzi
authors: G L
authors: GL
authors: Spadoni
authors: S
authors: S
authors: Pedicelli
authors: G
authors: G
authors: Scirè
authors: L
authors: L
authors: Cristofori
authors: E
authors: E
authors: Peschiaroli
authors: A
authors: A
authors: Deodati
authors: P
authors: P
authors: Cambiaso
authors: M
authors: M
authors: Cappa
authors: S
authors: S
authors: Cianfarani
mesh_terms: D001120:Arginine; D002648:Child; D003000:Clonidine; D005260:Female; D006130:Growth Disorders / Q000175:diagnosis* / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone; D019382:Human Growth Hormone / Q000097:blood* / Q000172:deficiency; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism; D008297:Male; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013268:Stimulation, Chemical
chemical_list: D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D013007:Growth Hormone-Releasing Hormone; D001120:Arginine; D003000:Clonidine