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

• Published in: ENDOCRINE JOURNAL Vol. 59; no. 9; pp. 771 - 780
• Main Authors: Katsumata, Noriyuki, Tachibana, Katsuhiko, Isojima, Tsuyoshi, Shimatsu, Akira, Horikawa, Reiko, Yokoya, Susumu, Chihara, Kazuo, Tanaka, Toshiaki, Hizuka, Naomi, Tatsumi, Ke-ita, Teramoto, Akira
• Format: Journal Article
• Language: English
• Published: Japan The Japan Endocrine Society 2012
• Subjects: Age Factors; Cohort Studies; Cross-Sectional Studies; Female; Humans; Insulin-Like Growth Factor I - analysis; Insulin-like growth factor-I; Japan; Japanese population; LMS method; Male; Normal Distribution; Radioimmunoassay; Reference intervals; Reference Values; Sex Characteristics; Statistics as Topic; Japan
• ISSN: 0918-8959; 1348-4540; 1348-4540
• DOI: 10.1507/endocrj.EJ12-0110

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.