CKD-MBD as a systemic disorder

Abstract

The kidney is one of themost important organs in the regulation of mineral metabolism [1]. In patients with chronic kidney disease (CKD), abnormalities in mineral metabolism inevitably develop without appropriate management. The biochemical abnormalities result from disturbances in calcium, phosphate, PTH, FGF-23, and vitamin D metabolism [2]. The spectrum of bone disease in CKD is quite broad, from high turnover bone disease (osteitis fibrosa and mixed renal osteodystrophy) to low turnover bone disease (osteomalacia, adynamic bone disease). Background pathologic states such as aging, diabetes and osteoporosis may modify the phenotype. In patients with long dialysis vintage, bone and joint disorders due to β2-M amyloid depositionmay develop as well. In addition to the classic abnormalities of bone and parathyroid structure and function, vascular calcification, especially that of the media [3], and valvular calcification have increasingly been considered to be part of this disorder associated with CKD and to play a potentially crucial role, both in terms of quality of life and of survival. Based on such a paradigm shift a new term, ‘CKD-Mineral and Bone Disorder (CKD-MBD)’, has been coined to describe the systemic consequences of mineral metabolism disturbances in CKD, which can no longer be considered to be restricted to bone disease [4]. Accordingly, the management of CKD-MBD should be ultimately aimed at decreasing the risk of cardiovascular events, bone fractures and mortality, rather than at solely correcting laboratory abnormalities, bone abnormalities or vascular calcification. This new concept has already been introduced into recent guidelines on CKD-MBD and will certainly be reflected others to come in the future. In this supplement issue of BONE, important mechanisms involved in the development of CKD-MBD as well as clinical aspects and management issues have been extensively discussed. We trust that further elucidation of the pathophysiology of this disorder will lead to better management and prognosis of CKD patients.