Diagnosis of osteoporosis with vitamin k as a new biochemical marker.

Osteoporosis is a metabolic bone disease characterized by reduced bone quality and quantity. As a consequence, patients are at risk for fractures, subsequent immobility, and higher mortality especially among elder patients. Because of the high incidence of complications and the associated financial burden for the health system, new parameters for diagnostic and therapeutic purposes are urgently needed. In this regard, research focused on vitamin K as a biochemical bone marker has provided promising results. Vitamin K represents an important enzyme-cofactor for the posttranslational modification and activation of several proteins involved in bone metabolism. Vitamin K has been proven to be a valuable diagnostic as well as therapeutic parameter especially in osteoporosis. Patients with osteoporosis have been shown to have decreased levels of vitamin K. Further, regular intake of vitamin K may increase bone mineral density (BMD), thereby lowering the fracture risk. Yet vitamin K alone may not sufficiently indicate the mineral status of the bone. However, the usefulness of a combination of several biochemical bone markers as improved surrogate markers of bone metabolism has been shown recently. Therefore, this review will focus on the significance and importance of vitamin K for bone metabolism. Beyond this, aspects on the current and prospective use of vitamin K as well as other newly developed biochemical bone markers will be discussed.