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Context:IGF-1 plays a role in bone metabolism. Although IGF-1 and bone mass both decrease with advancing age, their relationship in older individuals remains to be elucidated.Objective:The objective was to investigate associations of serum IGF-1 cross-sectionally with quantitative ultrasound and bone mineral density (BMD), and longitudinally with 3-year change in BMD and 10-year fracture risk in older individuals.Design, Setting, and Patients:The study included 627 men and 656 women aged ≥ 65 years from the Longitudinal Aging Study Amsterdam, an ongoing, population-based cohort study.Main Outcome Measures:Main outcome measures included baseline serum IGF-1 concentration; baseline quantitative ultrasound of the heel, including broadband ultrasound attenuation and speed of sound; BMD measured at several body sites at baseline and after 3 years; and prospective fracture incidence over 10 years. Associations were adjusted for relevant confounders.Results:Women, but not men, in the lowest quintile of IGF-1 concentration had lower broadband ultrasound attenuation (B = −4.53; P= .03) and a greater 3-year decrease in total hip BMD (B = −0.02; P= .05), than women in the highest quintile of IGF-1. Moreover, compared to women in the highest quintile of IGF-1, women in the combined lowest four quintiles of IGF-1 had an increased 10-year fracture risk (hazard ratio = 1.98; P= .05).Conclusions:Associations of lower IGF-1 with lower BUA, greater 3-year decrease in BMD, and increased 10-year fracture risk were only observed in women, not in men. These results support previous findings of gender differences in the relationship between IGF-1 and bone in older individuals.

Context:Vitamin D is essential for bone health. In addition, vitamin D has recently been proposed to play a role in the pathophysiology of many chronic diseases. Despite the large number of studies published on vitamin D, the threshold for a sufficient serum 25-hydroxyvitamin D [25(OH)D] concentration is still debated and may differ according to outcomes and subgroups.Objective:The objective of the study was to estimate the thresholds for serum 25(OH)D concentration with respect to the different outcomes and for different subgroups.Design, Setting, and Participants:Observational data from the Longitudinal Aging Study Amsterdam, an ongoing population-based Dutch cohort study [n = 1164, mean (SD) age 75.2 (6.5) y], were used.Main Outcome Measures:Falling, fractures, hypertension, cardiovascular disease, blood pressure, PTH, grip strength, physical performance, functional limitations, body mass index (BMI), and mortality were measured. To determine thresholds, spline curves were used. Visual inspection and the statistical best fit of the spline regression models were used together to estimate the best estimate of the thresholds.Results:Thresholds for serum 25(OH)D concentrations in the whole sample ranged from 46 nmol/L (PTH) to 68 nmol/L (hypertension). On average, women, the oldest old (≥75 y), and individuals with a high BMI (>25 kg/m2) had lower thresholds compared with men, the youngest old (65–75 y), and individuals with a low to normal BMI (<25 kg/m2).Conclusion:The results indicate that thresholds for serum 25(OH)D may vary according to different outcomes and subgroups. This study does not support the high thresholds (>75 nmol/L) as advised by some experts, and the higher requirements in women, older persons, and those with high BMI.