Serum IGF-I and IGFBP-3 Reference Values from a Chemiluminescent Assay in Normal Children and Adolescents of Hispanic and Italian Origin: Presence of Sexual Dimorphism in IGF-I Values

Abstract

Serum IGF-I and IGFBP-3 assays are used to monitor rhGH treatment. Some discrepancies in results obtained by means of different assays have been reported. The aim of this study was to establish normal ranges for circulating IGF-I and IGFBP-3 in children and adolescents of Hispanic and Italian origin. Circulating levels of IGF-I and IGFBP-3 were measured in 169 Hispanic and Italian prepubertal children and 66 adolescents of both sexes, using a chemiluminescent assay. Serum levels of IGF-I and IGFBP-3 increased from early childhood into adolescence. After pubertal peaks of IGF-I and IGFBP-3, slight decreases were observed with increasing age. Furthermore, serum IGF-I levels were significantly higher in girls than in boys, suggesting a sexual dimorphism in serum IGF-I values in late prepuberty and early puberty. Differences in IGF-I and IGFBP-3 absolute values between our study and previous studies suggest the need to establish reference ranges for each ethnic group.

Standardized centile curves and reference intervals of serum insulin-like growth factor-I (IGF-I) levels in a normal Japanese population using the LMS method

“…Scatter plots and smoothing curves of +2SD, +SD, Median, -SD, -2SD of serum IGF-I values in Japanese male (a) and female (b) subjects girls and 14 years of age in boys, compatible with the results of previous studies [9,10,[28][29][30][31][32]. These gender differences were in line with the observation that girls experience peak height velocity earlier than boys.…”

Association of serum components of the GH-IGFs-IGFBPs system with GHR-exon 3 polymorphism in normal and idiopathic short stature children

“…We found that the most important determinants of GHdependant inter-subject variability were Tanner stage and age. More previously seen by others, we found that IGF-I and ALS peaked earlier in girls than in boys during prepuberty, having their highest values at Tanner stage IV for both sexes [29][30][31][32][33][34]. Interestingly, the impact of age on IGF-I and ALS at prepuberty was only observed in girls, probably supporting the hypothesis of higher estradiol concentration in girls close to peripubertal ages [29].…”

“…IGF-I, IGFBP-3 an ALS underwent the dramatic changes during puberty [29][30][31][32][33][34]. Inter-subject variability in normal children was approximately 60% for IGF-I and GHBP and nearly 20-25% for IGFBP-3 and ALS concentration, resulting higher than the ones previously reported for adolescent and adult populations [35].…”

Serum insulin-like growth factor-I (IGF-I) reference ranges for chemiluminescence assay in childhood and adolescence. Data from a population of in- and out-patients

“…Two studies reported reference values in 1734 [16] and 837 [17] Chinese children and adolescents. More recently, Chaler et al [18] have tried to establish reference values in a study population made by 169 children and 66 adolescents.…”

“…However, the practical difficulty of obtaining blood samples from healthy children limits the possibility of adequate stratification by sex and age, as shown by all previous studies [14][15][16][17][18]. In addition, IGF-I levels in healthy children may be affected by ethnicity, age, sex, pubertal status, nutrient intake, body composition and acute illness.…”