THE AMINO-TERMINAL PROPEPTIDE OF TYPE I PROCOLLAGEN IN GROWTH HORMONE-DEFICIENT PATIENTS DURING TRANSITION PERIOD

Introduction. Bone mineral accretion continues beyond the attainment of final height during the transition period. Growth hormone deficiency (GHD) appears to have a significant effect on collagen turnover during childhood and less during adulthood. Amino-terminal propeptide of type I collagen (P1NP) is a marker of bone formation with low intra-individual when comparing to IGF1. Material and method. We evaluated 17 male patients diagnosed with GHD during childhood, after retesting GH axis in their transition period after at least 3 months from GH withdrawal. We correlate concentrations of P1NP and IGF1. We determined the predictive value for P1NP in identifying persistent GHD. Results. We found a strong positive correlation between IGF-1 and P1NP in the group of patients who maintained GH deficiency as young adults (r = 0.72, CI [0.02 to 0.94], p = 0.046). A threshold value for the P1NP of - 0.66 SDS predicts persistence of GHD with a sensitivity of 62.5% CI [24.5 to 91.5], specificity 75% CI [47.6 to 92.7] and AUC = 0.719 CI [0.5 0881]. We did not find a significant difference when we compared the AUC for the two parameters (p = 0.29). Conclusion. During the transition period, when the growth velocity is not available anymore, the dynamics of P1NP may be useful in quantifying the effectiveness of GH replacement therapy.