BACKGROUND: OSTEOPOROSIS RESULTS FROM REDUCED BONE MASS AND DISRUPTION OF THE MICRO-ARCHITECTURE OF BONE GIVING DECREASED BONE STRENGTH AND INCREASED RISK OF FRACTURE, PARTICULARLY OF THE SPINE, HIP, WRIST, HUMERUS, AND PELVIS. THE RISK OF FRACTURES INCREASES STEEPLY WITH AGE AND MOST OF THOSE AFFECTED ARE OVER 75.AGE RELATED BONE LOSS STARTS IN THE FOURTH OR FIFTHDECADE OF LIFE. IT OCCURS AS A RESULT OF INCREASEDBONE BREAKDOWN BY OSTEOCLASTS AND DECREASEDBONE FORMATION BY OSTEOBLASTS. THE ROLE OF OESTROGENDEFICIENCY IN MENOPAUSAL AND AGE RELATED BONE LOSS INWOMEN IS WELL DOCUMENTED, AND BONE MASS IN ELDERLYMEN IS ALSO POSITIVELY RELATED TO OESTROGEN LEVELS.VITAMIND INSUFFICIENCY AND SECONDARY HYPERPARATHYROIDISMARE COMMON IN ELDERLY PEOPLE AND MAYCONTRIBUTE. OTHER POSSIBLE FACTORS ARE REDUCED PHYSICALACTIVITY AND GENETIC FACTORS HAVE A STRONG INFLUENCE ON PEAKBONE MASS.SOME STUDIES HAVE BEEN SHOWED ON THE ROLE OF CYTOKINES AND CHEMOKINES IN THE PATHOGENESIS OF OSTEOPOROSIS, AND IT HAS BEEN SHOWN THAT MANY CYTOKINES ACTIVE IN INFLAMMATION AND IMMUNITY ALSO PLAY A ROLE IN PHYSIOLOGIC AND PATHOLOGIC RESORPTION OF BONE.