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Growth Horm IGF Res. 2008 Jun;18(3):228-37. Epub 2007 Nov 7.

Reference ranges of serum IGF-1 and IGFBP-3 levels in a general adult population: results of the Study of Health in Pomerania (SHIP).

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1
Institute for Community Medicine, Ernst Moritz Arndt University, Walther-Rathenau-Strasse 48, D-17487 Greifswald, Germany. nele.friedrich@uni-greifswald.de

Abstract

OBJECTIVE:

Insulin-like growth factor I (IGF-1), which is mostly carried by IGF binding protein 3 (IGFBP-3), mediates endocrine actions of growth hormone and represents an important prognostic factor for systemic diseases. The main objectives of the present study were (1) to calculate age- and sex-specific reference values for serum IGF-1 and IGFBP-3 levels using the Gaussian mean+/-1.96 *standard deviation method and the quantile regression method and (2) to perform a comparison of the results from both statistical methods.

DESIGN:

Cross-sectional study (Study of Health in Pomerania). The study population included 2499 men and women aged 20-79 years.

METHODS:

Serum IGF-1 and IGFBP-3 levels were determined by chemiluminescence immunoassays. Linear and quantile regressions were performed to calculate age- and sex-related reference ranges.

RESULTS:

Both statistical methods generated different results: The reference ranges based on linear regression identified 43 (1.7%) subjects with serum IGF-1 levels and 99 (4.0%) subjects with serum IGFBP-3 levels outside the reference range. Using quantile regression, 117 (4.7%) or 118 subjects (4.7%) with serum IGF-1 or IGFBP-3 levels outside the range were detected, respectively.

CONCLUSION:

The present study established age- and sex-specific reference ranges for serum IGF-1 and IGFBP-3 levels. Quantile regression should be preferred to calculate reference ranges because a better concordance to original data is possible due to no distribution assumption are required and the robustness against outliers is given.

PMID:
17997337
DOI:
10.1016/j.ghir.2007.09.005
[Indexed for MEDLINE]
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