76EMERGING ROLE OF BONE AS AN ENDOCRINE ORGANRole of bone as a target organ for action of various hormones of body is known since decades. But, surprising new discoveries in the past few years, of the novel hormones produced by bone cells is unfolding the hidden story of bone itself being an endocrine organ. Two novel hormones, Fibroblast Growth Factor 23 (FGF23) and Osteocalcin, produced exclusively by bone have been discovered and they function in a classic endocrine fashion. Fibroblast growth factor 23(FGF23) produced in bone by osteocytes, acts as a primary regulator of phosphate homeostasis by inhibiting phosophate reabsorption and calcitriol production in the kidney. Whereas, Osteocalcin produced in bone by osteoblasts, acts on three targets pancreas, adipose tissue and gonads. It thereby causes an increase in β-cell proliferation, insulin secretion and sensitivity, and male fertility. Thus, pointing to critical role of bone in several homeostatic processes and reproduction. The recognition of bone as a true endocrine organ has yet to be worked upon for the future research and as such may improve diagnosis and treatment of diseases like phosphatemic disorders, osteoporosis, diabetes mellitus and male infertilitydr.nadeema@gmail.comResearch512015Bone,Endocrine organ,FGF23,OsteocalcinNadeema Rafiq,Suchet Trigotra,Surjit Singh,Tauseef Nabi,Garima Charak,Owais Karnain L.S.DashoraDepartment of Physiology, Department of Medicine, MMIMSR, Mullana, Ambala, India,Department of Physiology, Department of Medicine, MMIMSR, Mullana, Ambala, India,Department of Physiology, Department of Medicine, MMIMSR, Mullana, Ambala, India,Department of Physiology, Department of Medicine, MMIMSR, Mullana, Ambala, India,Department of Physiology, Department of Medicine, MMIMSR, Mullana, Ambala, India,Department of Physiology, Department of Medicine, MMIMSR, Mullana, Ambala, India