ESPE Abstracts

Background: IGF1 is a biomarker of GH, and is often used to titrate the dose of GH therapy. However, IGF1 production is regulated by not only GH but also other factors.

Objective and hypotheses: We investigated whether the increase in IGF1 at several time points after the commencement of GH therapy could be a predictive factor for the improved growth.

Method: We studied 45 pre-pubertal patients with GH deficiency (GHD) that had continued with GH treatment for more than 2 years (29 boys and 16 girls). GHD was mild in 20 patients, moderate in 18, and severe in seven. We statistically analyzed the correlation between the following values: i) The increase in IGF1 (ΔIGF1) at 24 h, 4 months, 1 or 2 years after GH therapy was started; ii) The increase in height S.D. score (ΔHSDS) at 1 or 2 years.

Results: The ΔIGF1 24 h after GH therapy was started was significantly correlated with ΔHSDS at 2 years in mild and moderate GHD patients (P=0.021, r=0.511 and P=0.008, r=0.602 respectively). The ΔIGF1 at 4 months, 1 or 2 years in the mild and moderate GHD patients and at any time points in the severe GHD patients was not correlated with ΔHSDS.

Conclusion: This study clarified that the ΔIGF1 24 h after the initiation of GH therapy was significantly correlated with the improved growth of GHD patients. Since IGF1 is affected by various factors, i.e. nutrition and pubertal stage, its value immediately after the initiation of GH therapy is important to reflect the efficacy of GH. IGF1 24 h after the first injection of GH is an early and useful predictive factor for the efficacy of GH in GHD patients.