ESPE Abstracts

Background: Patients with childhood-onset GH deficiency (GHD) are usually retested in late adolescence or young adulthood, after achievement of final height, to verify whether they need to continue GH treatment. Most of the patients found to have idiopathic GHD when tested as children have normal GH responses when retested in the early or late adolescence. Indeed, the 2007 Consensus guidelines for the diagnosis and treatment of GHD adults recommended that idiopathic GHD patients should be re-evaluated.

Objective and hypotheses: The aim of the present study was to investigate if GH stimulation test is really necessary to confirm a permanent status of GHD or if IGF1 measurement alone at the same time could be used.

Method: We studied 163 children with idiopathic GHD (54 females and 109 males), age 16.2±1.4 years retested when they reached final height using GHRH (1 μg/kg i.v.)+arginine (0.5 g/kg i.v.) test or arginine alone (0.5 g/kg i.v.). GH and IGF1 levels were measured by a chemiluminescent assay (Immulite 2000).

Results: 39 (23.9%) patients showed severe GHD (GH peak at diagnosis <5 ng/ml) and 124 patients (76.1%) showed partial GHD (GH peak <10 ng/ml). By taking a peak GH value of <10 ng/ml in the arginine test and <19 ng/ml in the GHRH+arginine test, 28 patients (17.2%) were found to have persistent GHD and 135 (82.8%) to be transiently GH deficient. Among patients with severe GHD, 32 patients (82.1%) showed transient GHD, while among patients with partial GHD 103 (83.1%) children showed transient GHD. IGF1 levels were comparable between total GHD (0.13±1.04 SDS) and partial GHD subjects (0.18±0.84 SDS). Furthermore, among persistent total GHD patients only two showed very reduced levels of IGF1 (<−2.0 SDS), while in transient total GHD group no patients showed pathologically reduced IGF1 levels.

Conclusion: Most of the cases of idiopathic childhood-onset GHD is transient. The reasons for such findings are not clear but may include the variability of GH responses to stimulation. After the end of GH substitutive treatment, a re-evaluation of GH secretion is mandatory for reconfirming the diagnosis of GHD. IGF1 levels alone are not useful for discriminate persistent from transient GHD subjects.