Introduction and objective:
The expression of the C-type natriuretic peptide (CNP) gene has been detected in the growth cartilage of the long bones and vertebrae. This article provides an overview of the role of CNP in bone growth and presents the results of the authors’ research on the concentration of the NTproCNP and its relationship with growth velocity and bone markers in healthy school-age children.

Material and methods:
The study involved 75 girls and 59 boys aged from 9.0–11.8 years (mean 10.29±0.74). Body weight, height and lower limb length were measured, and blood samples were collected twice at six-month intervals. In the first serum sample, the concentrations of NTproCNP, C-terminal propeptide type I (CICP), C-terminal telopeptide type I collagen (ICTP) osteocalcin (OC) and bone-specific alkaline phosphatase (BAP) were determined. In the second sample, NTproCNP concentration was assessed.

Results:
During the six-month follow-up period, the increase in body height and weight of girls was greater than boys (p<0.000; p=0.003, respectively). While during the first examination the concentration of NTproCNP in girls and boys was similar, during the second examination it was higher in girls than in boys (p=0.04). Weak positive correlations between the increase in body height and NTproCNP, CICP, BAP as well as OC were found. There were no correlations between NTproCNP and the bone markers.

Conclusions:
The results suggest that NTproCNP concentration depends on growth velocity in children. There is increasing evidence that a better knowledge of CNP biology contributes to a better understanding of bone growth mechanisms.