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Low IGF-I level may predict fracture risk in men
Among healthy adults, lower levels of circulating insulin-like growth factor I are associated with increased risk for fracture, with the risk more pronounced among men, according to findings from a population-based study published in Clinical Endocrinology.
“Our study, including more than 3,500 adult men and women from the general population, suggests an important role of IGF-I on bone quality, especially in men,” Anke Hannemann, PhD, a researcher with the Institute of Clinical Chemistry and Laboratory Medicine, University Medicine Greifswald, Germany, told Endocrine Today. “A higher IGF-I level, but also a higher IGF-I to IGFBP-3 ratio, a marker for free IGF-I, is related to a better bone quality.”
Hannemann and colleagues analyzed data from 1,759 men (mean age, 52 years; 11.3% with diabetes) and 1,784 women (mean age, 51 years; 7.3% with diabetes) participating in the baseline examination of the Study of Health in Pomerania (SHIP)-Trend conducted in northeast Germany. Researchers assessed concentrations of IGF-I and IGFBP-3 (a marker for free IGF-I) and quantitative ultrasound measurements of the heel, and performed sex-specific linear and multinomial logistic regression analyses to measure the association between IGF-I level and bone parameters.
Among men in the cohort, 26.4% were classified as having medium fracture risk based on quantitative ultrasound, and 4.7% were classified as high risk for fracture. Among women, 31.7% and 5.8% were classified as medium and high risk, respectively.
In linear regression analyses, researchers found positive associations between IGF-I and IGF-I to IGFBP-3 ratio with all heel ultrasound parameters in men, with results persisting after adjustment for age, waist circumference, physical activity, diabetes status and high sensitivity C-reactive protein. In women, researchers observed an inverse association between IGF-I and fracture risk; however, no other associations between IGF-I and heel ultrasound parameters were observed, with results persisting after adjustment for menopausal status and other factors.
In multinomial logistic regression models, researchers also observed an inverse association between IGF-I and ultrasound-based fracture risk parameters in men. For each 1-standard deviation decrease in IGF-I concentration in men, risk for fracture increased by 18% for those with medium ultrasound-based fracture risk (95% CI, 1.03-1.36) and by 37% for those with high ultrasound-based fracture risk (95% CI, 1.01-1.85).
There was an observed association between IGF-I to IGFBP-3 and ultrasound-based fracture risk that did not rise to statistical significance.
Among women, a 1-standard deviation decrease in IGF-I level or the IGF-I to IGFBP-3 ratio was associated with 45% (95% CI, 1.04-2.02) or 37% higher odds (95% CI, 1-1.88), respectively, for those with high ultrasound-based fracture risk.
There was no association between IGFBP-3 and ultrasound-based fracture risk, according to researchers.
“Our findings might animate clinicians to refer patients with low IGF-I levels, particularly men, to a further evaluation of risk factors for osteoporosis and a detailed examination of the skeletal system,” Hannemann said. “Future studies might focus on the sex-dimorphism associated with GH/IGF-I-dependent mechanisms regulating bone structure and remodeling.” – by Regina Schaffer
For more information:
Anke Hannemann, PhD, can be reached at University Medicine Greifswald, Institute of Clinical Chemistry and Laboratory Medicine, Ferdinand-Sauerbruch-Straße, 17475 Greifswald, Germany; email: anke.hannemann@uni-greifswald.de.
Disclosures: The authors report no relevant financial disclosures.