In a meta-analysis, there was a weak association between irisin and lumbar BMD as well as femoral neck fracture; decreased irisin levels were associated with osteoporosis by pooled analysis and irisin levels were even lower in postmenopausal women and those with a history of fracture [9], suggesting that irisin might have utility as a marker for the assessment of metabolic bone disease. This evidence concerns the gene FNDC5 and osteoporosis.