Endocrine Abstracts

N-terminal peptide of type I procollagen (P1NP) is a marker of GH (hGH) anabolic action on bone formation. We evaluated the diagnostic value of P1NP in GH deficiency (GHD) in the transition period using receiver operating characteristic (ROC) plot analysis. We compared the diagnostic value of P1NP with IGF1. 16 male patients (chronological age, 16.6–21.5) with GH replacement therapy during childhood (ten IGHD and six MPHD) were evaluated at minimum 3 months after completion of treatment (1.86±1.46 years from rhGH withdrawal). A control group (CG) of nine healthy males (chronological age, 15.2–17.5) was selected. GH secretion was evaluated in IGHD group using insulin tolerance test and were divided as persistent IGHD (three patients) or reversible IGHD (seven patients) according to a GH cut-off below or above 5.6 ng/ml. There were no significant difference between IGF1 and P1NP in the control group and reversible IGHD group. The SDS for IGF1 and P1NP was calculated from the 16 participants with normal GH status (controls and reversible IGHD). The ROC plot showed that the best IGF1 SDS cut-off line was −0.76 (sensitivity (S), 87.5%; specificity (Sp), 88.9%, AUC=0.944). For P1NP SDS, the best cut-off line was −0.81 (sensitivity (S), 81.3%; specificity (Sp), 66.7%, AUC=0.743).

Conclusion: IGF1 is a better GH biomarker for diagnostic of persistent growth deficiency in the transition period with better specificity and sensibility comparing to P1NP.

Disclosure: This work was supported by the Educational Grant SOP HRD (POSDRU)/159/1.5/S/135760, 2014.