The Eagle Biosciences Human Osteoprotegerin (OPG) ELISA Assay Kit (enzyme-linked immunoassay kit) is intended for the quantitative determination of human osteoprotegerin levels in serum or plasma samples. The Eagle Biosciences Human Osteoprotegerin (OPG) ELISA Assay Kit is for research use only and not to be used in diagnostic procedures. Sample Types: serum, plasma. Range: 0 to 20 pmol/l. Sensitivity: LOD: (0 pmol/l + 3 SD): 0.07 pmol/l; LLOQ: 0.08 pmol/l. Time: 5.5 hours ? Osteoprotegerin (OPG) or Osteoclast inhibitory factor (OCIF) is a glycoprotein of the TNF receptor superfamily 11b (gene name TNFRSF11B). OPG is synthesized as a monomer of 380 amino acids and is assembled as a homodimer within the cell and then secreted mainly as a disulfide-linked homodimer into the extracellular compartment. OPG is produced by many different tissues and cell types including osteoblasts. OPG is a negative regulator of bone resorption by acting as decoy receptor for RANKL, thus neutralizing its function in osteoclastogenesis. This glycoprotein is also involved in the regulation of vascular calcification.