Bone Turnover and Bone Mineral Density Are Independently Related to Selenium Status in Healthy Euthyroid Postmenopausal Women

Context: Selenium status may have direct effects on bone and indirect effects through changes in thyroid hormone sensitivity. Objective: We hypothesized that variation in selenium status in healthy euthyroid postmenopausal women is associated with differences in bone turnover, bone mineral density (BMD) and fracture susceptibility. Design: The Osteoporosis and Ultrasound Study (OPUS) is a 6-yr prospective study of fracture-related factors. Setting: The study was comprised of a population-based cohort from five European cities. Participants: A total of 2374 postmenopausal women participated. Subjects with thyroid disease and nonthyroidal illness and those receiving drugs affecting thyroid status or bone metabolism were excluded, leaving a study population of 1144. Interventions: There were no interventions. Main Outcome Measures: We measured selenium (micrograms per liter); selenoprotein P (milligrams per liter); free T4 (picomoles per liter); free T3 (picomoles per liter); TSH (milliunits per liter); bone turnover markers; BMD; and vertebral, hip, and nonvertebral fractures. Results: Higher selenium levels were associated with higher hip BMD at study entry (β = 0.072, P = 0.004) and lower levels of bone formation (osteocalcin: β = −0.101, P < 0.001; procollagen type 1 N-terminal propeptide: β = −0.074, P = 0.013) and resorption markers (C-telopeptide of type 1 collagen: β = −0.058, P = 0.050; N-telopeptide of type 1 collagen: β = −0.095, P = 0.002). Higher selenoprotein P was associated with higher hip (β = 0.113, P < 0.001) and lumbar spine BMD (β = 0.088, P = 0.003) at study entry, higher hip BMD after the 6-yr follow-up (β = 0.106, P = 0.001) and lower osteocalcin (β = −0.077, P = 0.009), C-telopeptide of type 1 collagen (β = −0.075, P = 0.012), and N-telopeptide of type 1 collagen (β = −0.110, P < 0.001). Conclusion: Selenium status is inversely related to bone turnover and positively correlated with BMD in healthy euthyroid postmenopausal women independent of thyroid status.