[Bone and bone related biochemical examinations. Bone and collagen related metabolites. Receptor activator of NF-kappaB ligand (RANKL)].

Identification of RANKL (receptor activator of NF-kappaB ligand), RANK (receptor activator of NF-kappaB) and OPG (osteoprotegerin) revealed the mechanisms regulating osteoclast differentiation and function. RANKL-RANK signaling is essential for the physiological osteoclast development and plays a major role in the pathological bone destruction. RANKL is a transmembrane protein, but soluble form (sRANKL) is circulated in blood stream. Change of sRANKL concentration was observed in several bone diseases. This paper reviews the potential of sRANKL measurement as a marker of bone diseases.