Osteoporosis (OP) is one of most common age-associated and chronic metabolic bone diseases, featured by a decrease of bone mineral density (BMD) that increases the risk of bone fractures.OP guidelines agree that Dual-X-ray Absorptiometry (DXA) is the gold standard for BMD assessment, but for the different OP stages screening and diagnosis, BMD by itself is not an accurate predictor. Thus, OP is often misdiagnosed. Aim of the this study is to improve a tool for OP diagnosis based on the ability of circulating peripheral blood mononuclear cells (PBMCs) to maintain or not their in vitro viability (IRCCS Istituto Ortopedico Rizzoli European patent n.3008470 March 21, 2018) for the measurement of the different OP severity levels, also considering specific gender related differences.