BACKGROUND: The objective of the present study was to calculate age- and gender-specific reference ranges for serum insulin-like growth factor I (IGF-I) and insulin-like growth factor binding protein 3 (IGFBP-3) concentrations using quantile regression. METHODS: From the Study of Health in Pomerania (SHIP), 1798 men and women aged 25-85 years were recruited. Serum IGF-I and IGFBP-3 concentrations were determined using a chemiluminescent immunometric assay on an Immulite 2500 analyzer. Quantile regressions were performed to calculate the 2.5th and 97.5th percentiles. RESULTS: The reference ranges identified 43 (4.6%) women and 41 (4.8%) men with serum IGF-I concentrations, and 47 (5.0%) women and 42 (5.0%) men with serum IGFBP-3 concentrations outside the reference range. CONCLUSIONS: The use of quantile regression results in accurate calculation of age- and gender-specific reference ranges for serum IGF-I and IGFBP-3.
BACKGROUND: The objective of the present study was to calculate age- and gender-specific reference ranges for serum insulin-like growth factor I (IGF-I) and insulin-like growth factor binding protein 3 (IGFBP-3) concentrations using quantile regression. METHODS: From the Study of Health in Pomerania (SHIP), 1798 men and women aged 25-85 years were recruited. Serum IGF-I and IGFBP-3 concentrations were determined using a chemiluminescent immunometric assay on an Immulite 2500 analyzer. Quantile regressions were performed to calculate the 2.5th and 97.5th percentiles. RESULTS: The reference ranges identified 43 (4.6%) women and 41 (4.8%) men with serum IGF-I concentrations, and 47 (5.0%) women and 42 (5.0%) men with serum IGFBP-3 concentrations outside the reference range. CONCLUSIONS: The use of quantile regression results in accurate calculation of age- and gender-specific reference ranges for serum IGF-I and IGFBP-3.