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.
Measurements of insulin-like growth factor-I (IGF-I) are useful not only for diagnosis and management of patients with growth hormone (GH)-related disorders but also for assessing nutritional status.  We reported population-based references of serum IGF-I in 1996.  However, they did not properly reflect data in the transition period from puberty to maturity.  The aim of the present study was to re-establish a set of normative data for IGF-I for the Japanese population.  The study included 1,685 healthy Japanese subjects (845 males, 840 females) from 0 to 83 years old.  Subjects suffering from diseases that could affect IGF-I levels were excluded.  Obese or extremely thin adult subjects were also excluded.  IGF-I concentrations were determined by commercially available immunoradiometric assays.  The reference intervals were calculated using the LMS method.  Median IGF-I levels reached 310 ng/mL in males at the age of 14 years and 349 ng/mL in females at the age of 13 years, falling to 124 ng/mL and 103 ng/mL, respectively, by the age of 70 years.  The mean pretreatment IGF-1 SD scores in patients with severe GH deficiency (GHD) obtained from the database of the Foundation for Growth Science and from clinical studies for adult GHD were -2.1±1.6 and -4.9±2.5, respectively.  The present study established age- and gender-specific normative IGF-I data for the Japanese population and showed the utility of these references for screening patients with severe GHD.
GH and its Related Factors Study Committee and GH Treatment Study Committee, The Foundation for Growth Science in Japan, Tokyo 113-0033, Japan.
Tsuyoshi
T
Isojima
Akira
A
Shimatsu
Susumu
S
Yokoya
Kazuo
K
Chihara
Toshiaki
T
Tanaka
Naomi
N
Hizuka
Akira
A
Teramoto
Ke-ita
KI
Tatsumi
Katsuhiko
K
Tachibana
Noriyuki
N
Katsumata
Reiko
R
Horikawa
D000367:Age Factors; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D007564:Japan; D008297:Male; D016011:Normal Distribution; D011863:Radioimmunoassay; D012016:Reference Values; D012727:Sex Characteristics; D013223:Statistics as Topic
D007334:Insulin-Like Growth Factor I