Comparison of the difference in serum insulin growth factor-1 levels between chronological age and bone age among children

Abstract

ObjectiveBy measuring serum insulin-like growth factor-1 (IGF-1) levels in children aged 2–16, we aimed to analyze the changes in IGF-1 levels in different sex and age groups, and compare the consistency of IGF-1 results evaluated by chronological age (CA) and bone age (BA) in children. MethodsA cross-sectional study was conducted between January 2017 and December 2020 among 2979 relatively healthy children who attended the Department of Growth and Development outpatient clinic and health care center of the Affiliated Children’s Hospital of the Capital Institute of Pediatrics and underwent health examination and development assessment. Height, weight, and Tanner pubertal stage were measured by pediatricians. The CHN method was used to estimate BA. Venous blood samples were collected from the children, and IGF-1 levels were determined via chemiluminescence. ResultsIGF-1 levels in childhood increased slowly with age, dramatically during puberty,and continuously withgrowth until to 15 years for boys and reached a peak value at 13 years for girls based on CA. IGF-1 levels reached peak values at 14 and 13 years for boys and girls, respectively, based on BA. There were differences in IGF-1 values between the CA and BA groups at the age of 10–11 years for boys and 7–11 years for girls. A total of 103 boys (7.7%) and 17 girls (1.0%) had IGF-1 levels below the lower limit of the reference range based on CA; evaluating based on BA, there were 82 boys (6.1%) and 15 girls (0.9%) still had IGF-1 values less than the lower limit of the reference range. Eighteen boys (1.3%) and 173 girls (10.5%) had IGF-1 levels above the upper limit of the reference range based on CA; evaluating based on BA, these numbers reduced to 5 (0.4%) among boys and 41 (2.5%) among girls. ConclusionsThere is a significant difference between BA and CA in evaluating IGF-1 levels in children, which can significantly reduce the proportion of IGF-1 values above the upper limit of the kit reference range in children. This suggests that children with BA advanced in pubertal period, the evaluating results of IGF-1 should be corrected by using BA.