Rapid suppression of plasma alkaline phosphatase activity after renal transplantation in patients with osteodystrophy.

Plasma alkaline phosphate activity is a important marker of increased skeletal turnover (both resorption and formation) and bone disease in uraemia, but its value after renal transplantation is uncertain. The rate of fall of alkaline phosphatase was compared in three groups of uraemic patients with osteodystrophy and elevated serum alkaline phosphatase undergoing either renal transplantation, parathyroidectomy or therapy with 1a hydroxylated vitamin D derivates. Alkaline phosphatase fell after transplantation, irrespective of graft function, with a half-time significantly less than the other treatments (p less than 0.001). We suggest that this represents a direct inhibitory effect of steroids on osteoblasts and that alkaline phosphatase is thus an unreliable marker of bone resorption after transplantation.