Vitamin D, paarthyroid function and renal bone disease: interplay with FGF23

Metabolic bone diseases in patients with chronic kidney disease (CKD) are not uncommon and are referred to as CKD-mineral and bone disorder (CKD-MBD). This chapter discusses the interplay of vitamin D, parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) in the pathogenesis of CKD-MBD as the glomerular filtration rate declines. Key features discussed include the role of vitamin D, PTH and FGF23 in calcium (Ca) and phosphate (P) homeostasis, and its effect on bone mineralization. It also highlights the various available surrogate biomarkers and their strengths and limitations in evaluation CKD-MBD and bone turnover. As CKD-MBD is a complex disorder that requires early identification and accurate management strategies we have tried to address the diagnostic caveats and how metabolic bone markers and hormones can address these challenges for improving patient outcomes.