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Low serum estradiol levels put older men at high risk for bone fracture
Men experiencing low estradiol serum levels in the later stages of life may be at an increased risk for bone fracture due to an associated reduction of cortical bone strength and increased porosity, researchers said.
A team of investigators at the University of Gothenburg in Sweden studied 440 men (mean age, 80 years) with high-resolution peripheral quantitative CT (HR-pQCT) and sex steroid analysis available to find associations between bone microstructural parameters and the steroid levels. Participants were from the 5-year follow-up of the population-based Osteoporotic Fractures in Men Sweden Study.
Researchers measured trabecular and cortical bone microstructure at the distal tibia using a HR-pQCT device with a nominal isotropic resolution. Levels of serum estradiol (E2) and testosterone were analyzed with a validated gas chromatography tandem mass spectrometry system. Free E2 and free testosterone levels were calculated using law-of-mass-action equations.
Age-adjusted models showed that E2 and free E2 associated significantly inversely with cortical porosity (P<.05) and cortical pore diameter (P<.001) but not testosterone or free testosterone. Models including both serum E2 and testosterone demonstrated that E2 (P<.05) but not testosterone associated independently with cortical porosity. There was a similar independent association for free E2 (P<.05) but not free testosterone.
“Accumulating evidence shows that a minimum E2 level is required for prevention of bone loss and fractures, and this threshold appears to be more apparent at cortical than trabecular sites,” the researchers wrote.
Funding: This work was supported by the Swedish Research Council, the Swedish Foundation for Strategic Research, the ALF/LUA research from the Sahlgrenska University Hospital, the Lundberg Foundation, the Torsten and Ragnar Söderberg’s Foundation, the Novo Nordisk Foundation and Gustaf V’s and Queen Victoria’s Freemason Foundation.
Disclosure: The researchers report no relevant financial disclosures.