Monitoring Growth And Growth-Hormone Therapy By Serum Determination Of Antigens Related To The Amino-Terminal Type-Iii Procollagen Propeptide (P-Iii-Np)

Serum P-III-NP reflects fibriliogenesis. To study whether P-III-NP can be used to monitor growth, it was determined by two different radioimmunoassays. One recognizes predominantly the intact triple-stranded propeptide showing a lesser affinity to the smaller monomeric peptide (RIAgnost), while the other detects both forms equally (FAB). In healthy children (n=375, aged 0 to 16 years) p-III-NP determined with either assay followed closely growth velocity. Patients with Turner's-Syndrome (n=11: 17±4/90± 22 (RIAgnost/FAB in ng/ml respectively)), constitutional short stature (n=16: 19±5/105±27) and growth hormone deficiency (GHD) (n=23: 16±8/82±29) had low levels, while those with tall stature (n=11: 56±45/174±38) had high levels, which declined during estradiol-therapy in girls (n=3: 23±4/125±22). In GHD during recombinant growth hormone therapy (n=20) p-III-NP values increased after only 3 injections (p<0.01) and stayed elevated above baseline for 6 months (ms). Results were compared to growth (median 5.6 cm (0.4 to 13.9) in 6 ms) and to established methods of growth monitoring (somatomedin c, alkaline phosphatase). p-III-NP (FAB) values correlated with the individual growth rates during the first (r=0.40; p<0.05) and the second 3 ms (r=0.66; p<0.001) and the total 6 ms periods (r=0.46 p<0.05). All other parameters showed some association to growth only during one or two treatment periods. Thus, p-III-NP can be used for growth monitoring.