Combined growth hormone-releasing hormone and growth hormone-releasing peptide-6 test for the evaluation of growth hormone secretion in children with growth hormone deficiency and growth hormone neurosecretory dysfunction.
BACKGROUND
The combined growth hormone-releasing hormone and growth hormone-releasing peptide-6 (GHRH + GHRP-6) test is most potent in evaluating GH secretion.


OBJECTIVE
To assess its capability in children with GH deficiency and low spontaneous GH secretion (GH neurosecretory dysfunction).


METHODS
35 children with GH <10 microg/l after levo-dopa/clonidine (GHD), 15 with normal provocative tests but abnormal 24-hour spontaneous GH secretion (GHND), and 20 controls (C) were given 1 microg/kg of GHRH and GHRP-6 i.v. and GH (microg/l) was measured at -15, 0, 5, 10, 15, 30, 45 and 60 min.


RESULTS
Six were nonresponders to the combined test, with significantly lower peak GH 20.7 (7.8-31.8) than C and the rest of the patients (responders). Peak GH was similar between prepubertal (PP) controls 167 +/- 88, GHD 202 +/- 110 and GHND 155 +/- 83. Pubertal (P) controls had higher peak GH 328 +/- 149 than P-GHD 203 +/- 105 and P-GHND 186 +/- 105. While P-C had higher peak GH than PP-C, PP and P children had similar responses within the GHD and GHND groups.


CONCLUSIONS
The GHRH + GHRP-6 test detects children with severe GH insufficiency. Patients with GHD respond similarly to those with GHND, indicating a possible hypothalamic GH neuroregulatory dysfunction in GHD. Responders to the combined test may be eligible for treatment with a synthetic GH secretagogue.
Spiliotis
Bessie E
BE
Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, University of Patras, School of Medicine, Patras, Greece. besspil@endo.gr
Papadimitriou
Dimitrios T
DT
Alexandrides
Theodore K
TK
Karystianos
Christoforos
C
Nikiforidis
George
G
Vassilakos
Pavlos
P
Beratis
Nicholas G
NG
Casanueva
Felipe F
FF
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D013007:Growth Hormone-Releasing Hormone / Q000008:administration & dosage*; D006728:Hormones / Q000008:administration & dosage*; D019382:Human Growth Hormone / Q000097:blood* / Q000172:deficiency*; D006801:Humans; D007031:Hypothalamus / Q000378:metabolism*; D007275:Injections, Intravenous; D008297:Male; D009842:Oligopeptides / Q000008:administration & dosage*
D006728:Hormones; D009842:Oligopeptides; D019382:Human Growth Hormone; C041048:growth hormone releasing hexapeptide; D013007:Growth Hormone-Releasing Hormone