Whats new in vitamin D for the nephrologist?
Department of Renal Medicine and Transplantation, Royal London Hospital, Whitechapel, London, UK Correspondence and offprint requests to: Dr J. Cunningham, Department of Renal Medicine and Transplantation, Royal London Hospital, Whitechapel, London E1 1BB, UK. Introduction In this review we discuss some of the clinical implications of progress in our understanding of the action of vitamin D and its derivatives on calcium, phosphate homeostasis and skeletal function in uraemia. The parathyroid glands synthesize and secrete parathyroid hormone (PTH) in response to low calcium, low 1,25-dihydroxyvitamin D3 (calcitriol), and high phosphate concentrations. The interplay between these elements is complex, operating through several feedback mechanisms. Both PTH and calcitriol regulate circulating calcium and phosphate concentrations through their action on target organs, namely the kidney, bone, and intestine. PTH and calcitriol regulate one another’s production, and additionally are both reg
