Serum bone alkaline phosphatase is superior to plasma levels of bone matrix proteins for assessment of bone metabolism in patients receiving renal transplants

Abstract The plasma concentrations of two bone matrix proteins (osteocalcin, osteonectin) were monitored in 56 samples from 14 patients receiving renal transplants and the values compared with serum bone alkaline phosphatase mass concentrations and osteotropic hormone levels (parathyroid hormone, calcitriol). There were no significant changes in the concentrations of plasma osteonectin at any time after transplantation, as compared with the values before transplantation ( P > 0.1). None of the plasma samples showed osteonectin levels above the reference interval. There was a weak but significant relationship between platelet counts and plasma osteonectin levels ( r = + 0.322; P P > 0.5) whereas 3 months after transplantation bone alkaline phosphatase levels were higher than before transplantation ( P P P > 0.05). After transplantation there was a lack of correlation between serum bone alkaline phosphatase mass concentrations and plasma osteocalcin values ( P > 0.05). In conclusion, serum bone alkaline phosphatase should be preferred to bone matrix proteins for the assessment of bone metabolism in patients receiving renal transplants: (a) bone alkaline phosphatase — but not osteocalcin — is significantly correlated with calcitriol and adequately reflects increased bone formation after renal transplantation; (b) interpretation of osteocalcin values is severely hampered by their strong correlation with serum creatinine concentrations; (c) plasma osteonectin determinations are not useful for monitoring bone formation.