Abbreviations

[Ca2+e] : extracellular Ca2+

CaR : Ca2+-sensing receptor

CKD: chronic kidney disease

DBP : vitamin D-binding protein

EGF-R : epidermal growth factor receptor

ESRD : end-stage renal disease

FGF-23 : Fibroblast-growth factor-23

1° hyperparathyroidism : primary hyperparathyroidism

2° hyperparathyroidism : secondary hyperparathyroidism

Ki67 : cell-cycle linked antigen

MEN-1 : multiple endocrine neoplasia type-1

PCNA : cell-cycle linked antigen (“proliferating cell nuclear antigen”)

PTH : parathyroid hormone

iPTH : intact PTH

PTH-R : PTH receptor

PTHrp : parathyroid hormone-related peptide

PTX : parathyroidectomy

TGF-α : transforming growth factor-α

VDR : vitamin D receptor

VDRE : VDR response element

Chronic kidney disease (CKD) is almost constantly associated with disturbances of calcium and phosphate metabolism. These disturbances occur early in the course of CKD. Initially, they are characterized by a tendency towards hypocalcemia, fasting hypophosphatemia, and diminished plasma calcitriol concentration, together with a progressive increase in plasma intact parathyroid hormone (iPTH) and the development of osteitis fibrosa. The latter is the consequence of a longstanding stimulation of bone turnover by excessive PTH secretion. In the last decade, however, the increasing recognition of this complication led to frequent oversuppression of PTH by the administration of excessive calcium and/or vitamin D supplements, with its skeletal consequence of iatrogenic low-turnover bone disease. Nephrologists have become progressively aware of the fact that the abnormally high calcium and phosphate levels associated with both hyper and hypoparathyroidism are detrimental to CKD patients, not only in terms of abnormal bone structure and function, but also in terms of soft-tissue calcification and cardiovascular as well as all-cause mortality . The complex disturbances of mineral and bone metabolism associated with CKD have traditionally been termed renal osteodystrophy and classified based on bone biopsy. However, bone biopsy is not readily available for clinical management. Therefore, a new definition and classification system is proposed, called «CKD-Mineral and Bone Disorder» (CKD-MBD), to describe this broader clinical syndrome which is manifested by any one or a combination of abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism, abnormalities in bone turnover, mineralization, volume, linear growth, or strength, and vascular or other soft tissue calcification.