Monitoring of bone resorption after renal transplantation by measuring the urinary excretion of pyridinium cross-links

One and three months after renal transplantation, the urinary excretion of pyridinium cross-links was higher (p 0.05). This rise in the excretion of pyridinium cross-links is probably due to an increase of bone resorp- tion caused by cyclosporin A and/or glucocorticoids. In the case of 17 urines with excretion values of pyridinium cross-links above the upper reference limit (pyridinoline equivalents, 93 /mol creatinine), only 2 (12%) of the corresponding sera showed increased bone alkaline phosphatase values. In patients following renal transplantation simultaneous assessment of bone formation and bone resorption (determined from bone alkaline phosphatase serum concentrations and the excretion of pyridinium cross- links) may therefore enhance the diagnostic sensitivity for detecting effects on bone metabolism.