Endocrine Abstracts

Aim: Somatic growth results from the generation of new support and connective tissue. Since collagen is the major protein constituent of connective tissue, its synthesis must be a prerequisite for the normal growth. The aim of the study was to determine age-related reference intervals for P3NP, a collagen – formation marker in a group of normal height prepubertal children and to compare to IGF1 levels.

Subjects: Forty-three prepubertal children, male (n=26) and female n=(17) participated in this study. Their height and weight were recorded. All the children have normal height.

Methods: For quantitative measurement of P3NP, we used a research kit with sandwich enzyme immunoassay with a detection limit of 62.5 pg/ml. P3NP values were analyzed for normality using Shapiro–Wilk test. Tukey test was used to identify outliers. We divided the prepubertal period into three intervals for each sex: 4 to 5-year old, 6 to 7 year old, and 8 to 9 year old.

Results: Age was determinant for the standard deviation score but not for the mean of P3NP values for each age group. A t-test was used to compare means and SDS for each sex and age-group. There were similar values for P3NP between males and females in the group of age 4 to 5-year old and 6 to7 years old. There was a trend towards significant higher values for P3NP in the girls when compared with the male in the age group of 8 to 9-year-old. No correlation between IGF1 and P3NP was fond.

Conclusion: Higher values for P3NP in girls compared to males in the group of 8 to 9 year old can be explained by an earlier onset of puberty in girls associated with the increase during early puberty of collagen markers.