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Eur J Endocrinol. 2016 Jul;175(1):41-7. doi: 10.1530/EJE-16-0105. Epub 2016 May 4.

Cut-off limits of the peak GH response to stimulation tests for the diagnosis of GH deficiency in children and adolescents: study in patients with organic GHD.

Author information

1
SSD Endocrinologia PediatricaOspedale Pediatrico Microcitemico "A. Cao", Cagliari, Italy.
2
Ospedale Generale RegionaleBolzano, Italy.
3
Clinica Pediatrica, Istituto Giannina Gaslini, Universitá di GenovaGenova, Italy.
4
Universitá di BolognaOspedale S.Orsola-Malpighi, Bologna, Italy.
5
UOC di Endocrinologia e DiabetologiaOspedale Pediatrico Bambino Gesú IRCCS, Roma, Italy.
6
SSD Endocrinologia PediatricaOspedale Pediatrico Microcitemico "A. Cao", Cagliari, Italy sandro.loche@aob.it.

Abstract

OBJECTIVE:

The diagnosis of GH deficiency (GHD) in children and adolescents is established when GH concentrations fail to reach an arbitrary cut-off level after at least two provocative tests. The objective of the study was to define the optimal GH cut-offs to provocative tests in children and adolescents.

DESIGN:

Retrospective study in 372 subjects who underwent evaluation of GH secretion. GH and IGF-I were measured by chemiluminescence assay in all samples. Receiver operating characteristic (ROC) analysis was used to evaluate the optimal GH cut-offs and the diagnostic accuracy of provocative tests.

METHODS:

Seventy four patients with organic GHD (GH peak <10μg/L after two provocative tests) and 298 control subjects (GH response >10μg/L to at least one test) were included in the study. The provocative tests used were arginine, insulin tolerance test (ITT) and clonidine. Diagnostic criteria based on cut-offs identified by ROC analysis (best pair of values for sensitivity and specificity) were evaluated for each test individually and for each test combined with IGF-I SDS.

RESULTS:

The optimal GH cut-off for arginine resulted 6.5μg/L, 5.1μg/L for ITT and 6.8μg/L for clonidine. IGF-I SDS has low accuracy in diagnosing GHD (AUC=0.85). The combination of the results of provocative tests with IGF-I concentrations increased the specificity.

CONCLUSIONS:

The results of the ROC analysis showed that the cut-off limits which discriminate between normal and GHD are lower than those commonly employed. IGF-I is characterized by low diagnostic accuracy.

PMID:
27147639
DOI:
10.1530/EJE-16-0105
[Indexed for MEDLINE]

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