Association between serum cystatin C and bone mineral density in Korean adults

Background: Serum cystatin C has been known as a novel marker of preclinical renal dysfunction, and higher cystatin C levels are associated with increased risks of hip and nonvertebral fractures. However, there are few reports on the association between serum cystatin C and bone mineral density (BMD), especially in the Asian population. We evaluated the association between cystatin C levels and BMD of the spine and hip in Korean adults. Methods: A cross-sectional study was performed in 865 Korean adults (325 men and 540 women) who participated in a comprehensive medical examination program and underwent bone densitometry. Renal function was assessed by the estimated glomerular filtration rate (eGFR), which was calculated using an equation based on creatinine (eGFRcre) and cystatin C (eGFRcys). Results: The serum cystatin C level was negatively correlated with different types of BMD, including the lowest lumbar, total lumbar, femoral neck, and total femur BMD, in women, but not in men. Higher cystatin C levels were associated with a higher prevalence of osteoporosis in women (odds ratio [OR], 3.68; 95% confidence interval [CI], 1.69-8.03; P=0.001), but not in men (OR, 0.85; 95% CI, 0.30-2.38; P=0.761). However, this association was attenuated in the multivariable model adjusted for age, body mass index, serum 25-hydroxyvitamin D-3, and creatinine (OR, 1.01; 95% CI, 0.38-2.71) in women. In addition, the eGFRcys showed a stronger positive correlation with BMD than the eGFRcre. Conclusion: Our findings suggest that serum cystatin C levels might help identify women with osteoporosis who are susceptible to fractures.