Men with metabolic syndrome have lower bone mineral density but lower fracture risk--the MINOS study

Data on the association of the metabolic syndrome (MetS) with bone mineral density (BMD) and fracture risk in men are inconsistent. We studied the association between MetS and bone status in 762 older men followed up for 10 years. After adjustment for age, body mass index, height, physical activity, smoking, alcohol intake, and serum 25-hydroxycholecalciferol D and 17beta-estradiol levels, men with MetS had lower BMD at the hip, whole body, and distal forearm (2.2% to 3.2%, 0.24 to 0.27 SD, p < .05 to .005). This difference was related to abdominal obesity (assessed by waist circumference, waist-hip ratio, or central fat mass) but not other MetS components. Men with MetS had lower bone mineral content (3.1% to 4.5%, 0.22 to 0.29 SD, p < .05 to 0.001), whereas differences in bone size were milder. Men with MetS had a lower incidence of vertebral and peripheral fractures (6.7% versus 12.0%, p < .05). After adjustment for confounders, MetS was associated with a lower fracture incidence [odds ratio (OR) = 0.33, 95% confidence interval (CI) 0.15-0.76, p < .01]. Among the MetS components, hypertriglyceridemia was most predictive of the lower fracture risk (OR = 0.25, 95%CI 0.10-0.62, p < .005). Lower fracture risk in men with MetS cannot be explained by differences in bone size, rate of bone turnover rate and bone loss, or history of falls or fractures. Thus older men with MetS have a lower BMD related to the abdominal obesity and a lower risk of fracture related to hypertriglyceridemia. MetS probably is not a meaningful concept in the context of bone metabolism. Analysis of its association with bone-related variables may obscure the pathophysiologic links of its components with bone status.