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- Title
Low Circulating Insulin-Like Growth Factor I Bioactivity in Elderly Men Is Associated with Increased Mortality.
- Authors
Brugts, M. P.; van den Beld, A. W.; Hofland, L. J.; van der Wansem, K.; van Koetsveld, P. M.; Frystyk, J.; Lamberts, S. W. J.; Janssen, J. A. M. J. L.
- Abstract
Context: Low IGF-I signaling activity prolongs lifespan in certain animal models, but the precise role of IGF-I in human survival remains controversial. The IGF-I kinase receptor activation assay is a novel method for measuring IGF-I bioactivity in human serum. We speculated that determination of circulating IGF-I bioactivity is more informative than levels of immunoreactive IGF-I. Objective: Our objective was to study IGF-I bioactivity in relation to human survival. Design, Setting, and Study Participants: We conducted a prospective observational study at a clinical research center at a university hospital of 376 healthy elderly men (aged 73–94 yr).Main Outcome Measures: IGF-I bioactivity was determined by the IGF-I kinase receptor activation assay. Total and free IGF-I were determined by IGF-I immunoassays. Mortality was registered during follow-up (mean 82 months).Results: During the follow-up period of 8.6 yr, 170 men (45%) died. Survival of subjects in the highest quartile of IGF-I bioactivity was significantly better than in the lowest quartile, both in the total study group [hazard ratio (HR) = 1.8; 95% confidence interval (95% CI) = 1.2–2.8; P = 0.01] as well as in subgroups having a medical history of cardiovascular disease (HR = 2.4; 95% CI = 1.3–4.3; P = 0.003) or a high inflammatory risk profile (HR = 2.3; 95% CI = 1.2–4.5; P = 0.01). Significant relationships were not observed for total or free IGF-I. Conclusion: Our study suggests that a relatively high circulating IGF-I bioactivity in elderly men is associated with extended survival and with reduced cardiovascular risk.
- Publication
Journal of Clinical Endocrinology & Metabolism, 2008, Vol 93, Issue 7, p2515
- ISSN
0021-972X
- Publication type
Article
- DOI
10.1210/jc.2007-1633