Reference values for serum levels of insulin-like growth factor (IGF-1) and IGF-binding protein 3 (IGFBP-3) and their ratio in Chinese adolescents.
OBJECTIVE
To establish the reference values for serum levels of IGF-1 and IGFBP-3 and their ratio in Chinese adolescents aged 12-19 years.


METHODS
2102 Chinese adolescents were randomly selected from all secondary schools in Hong Kong with 1734 having IGF-1 and IGFBP-3 levels as measured by automated chemiluminescent assays (IMMULITE 2000). LMS (Lambda-Mu-Sigma) method was used to generate reference percentile curves for IGF-1, IGFBP-3 and their ratio.


RESULTS
After excluding participants with abnormal thyroid function, 798 boys and 894 girls were included in the analysis with a mean (+/-SD) age of 15.3 (+/-2.0) and 15.7 years (+/-2.0), respectively. Both serum IGF-1 and IGFBP-3 levels tended to be higher in girls than boys before the age of 16. In boys, there was progressive decline in IGF-1 after a pubertal peak at the age of 13-14. In girls, there was a similar decline after the age of 12. In both boys and girls, there was progressive age-dependent decline in IGFBP-3 after the age of 15-16. The pattern of changes for IGF-1/IGFBP-3 ratio was similar to that of the IGF-1 levels.


CONCLUSIONS
These reference values of IGF-1 and IGFBP-3 in healthy adolescents should facilitate the clinical management of adolescents with GH-IGF axis disorders.
Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
Alice P S
AP
Kong
Gary W K
GW
Wong
Kai-Chow
KC
Choi
Chung-Shun
CS
Ho
Michael H M
MH
Chan
Christopher W K
CW
Lam
Peter C Y
PC
Tong
Risa
R
Ozaki
Wing-Yee
WY
So
Ronald C W
RC
Ma
Joseph T F
JT
Lau
Juliana C N
JC
Chan
D000293:Adolescent; D000328:Adult; D002681:China; D003940:Diagnostic Techniques, Endocrine / Q000592:standards; D005260:Female; D006130:Growth Disorders / Q000175:diagnosis; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D008297:Male; D012016:Reference Values; D012727:Sex Characteristics
C515497:IGFBP3 protein, human; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I