Sequential Changes in Vitamin D and Calcium Metabolism after Successful Renal Transplantation

Abstract

A prospective study was made of sequential changes in the metabolism of vitamin D and calcium in 19 allograft recipient during the first year after successful renal transplantation. All but one of the patients received cyclosporine A combined with corticosteroids and azathioprine as immunosuppressive therapy. Shortly after transplantation most patients showed transient hypocalcemia and hypophosphatemia. At the time of transplantation 17 of 19 patients had an elevated plasma intact parathyroid hormone (PTH) level, and at the close of follow-up one in four patients. In six other patients intact PTH was within the reference range, but high in relation to simultaneously measured serum ionized calcium. Accordingly, one year after transplantation less than half of the patients showed complete resolution of hyperparathyroidism. The change towards normal in the metabolism of vitamin D began within the first post-transplantation week irrespective of the onset of diuresis. One to two weeks after transplantation 1,25(OH)₂D₃ and 24,25(OH)₂D₃ reached the lower limit of normal range. In these renal allograft recipients who received cyclosporine A the long-term values of serum 1,25(OH)₂D₃ did not differ from those of normal subjects.

Keywords:

• calcium
• cyclosporin A
• hyperparathyroidism
• kidney transplantation
• phosphate
• vitamin D