Relationship between serum adiponectin and bone mineral density in male patients with obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is reported to have an association with bone mineral density (BMD). However, the underlying mechanism is far from clear. The aim of this study was to investigate the relationship between OSAS, bone turnover markers, and BMD and to evaluate the effect of adiponectin on BMD in patients with OSAS. Seventy-one male patients with OSAS and 13 male control subjects were enrolled in this study. Serum adiponectin, calcium, phosphorus, 25-hydroxyvitamin-D3, β-isomerized form C-terminal telopeptide of type I collagen, osteocalcin, and procollagen type 1 N-propeptide were measured in all subjects, and BMD was evaluated by dual-energy X-ray absorptiometry (DEXA) in the lumbar spine (L1–L4), the femoral neck, and the hip total. No statistically significant differences were found between the studied groups in terms of demographic data and bone turnover markers. Serum adiponectin significantly decreased with the aggravation of OSAS. Compared with subjects without OSAS, those with OSAS had a higher hip total BMD and t scores (p = 0.027 and p = 0.028). The significant negative association was found between serum adiponectin levels and hip total BMD. After adjusting for confounders, adiponectin as well as oxygen desaturation index (ODI) significantly predicted the hip total BMD (β = −0.232, p = 0.005 and β = 0.226, p = 0.037). In male subjects, the presence of obstructive sleep apnea syndrome is associated with higher bone mineral density of the hip. These findings suggest that serum adiponectin may be an underlying mediator for BMD in OSAS.