IGF-I and IGFBP-3 assessment in the management of childhood onset growth hormone deficiency.

The diagnosis of growth hormone (GH) deficiency (GHD) in childhood is not straightforward, being still based on a comprehensive clinical, anthropometric, endocrine and neuroradiological assessment. Due to their GH dependency and relative stability in circulation, IGF-I and IGFBP-3 serum concentrations were proposed as reliable indicators of daily GH secretion. However, the sensitivity of assays for both IGF-I and IGFBP-3 is inadequate to exclude the diagnosis of GHD merely on the basis of a normal value of the two parameters, although it seems likely that IGF-I values higher than -1 SD reflect a normal GH secretion. On the other hand, as the specificity of both measurements is over 90%, subnormal concentrations strongly support the diagnosis of GHD. Finally, combining the evaluation of growth velocity with IGF-I measurement, sensitivity and specificity reach a value > or =95%, implying that two subnormal values strongly suggest and two normal values strongly oppose the diagnosis of GHD.