DIAGNOSTIC-VALUE OF PYRIDINOLINIC URINARY COLLAGEN CROSS-LINKS IN HYPERPARATHYROIDISM OF KIDNEY-TRANSPLANT PATIENTS

Successful renal transplantation may, be complicated by persistent hyp erparathyroidism or its onset. In normocalcemic venal transplant patie nts, abnormal parathyroid function may exist, especially when they are challenged with IV calcium infusion. Presently the urinary pyridinium cross-links pyridinoline (Pyd) and deoxypyridinoline (Dpd) are the mo st widely used biochemical markers of bone resorption. To evaluate a m ore sensitive and specific index for bone resorption in 50 normocalcem ic renal transplant patients (Group A consisting of 38 patients on cor ticosteroid therapy and group B consisting of 12 patients not on corti costeroid therapy, with slightly increased intact parathormone (iPTH) and alkaline phosphatase (ALP) serum levels, and normal total calcium (Ca), phosphorus (P), and osteocalcin (BGP) serum levels, urinary Pyd and Dpd were tested by ELISA. No patient runs taking drugs which affec ted bone metabolism. Our results in all patients indicated increased P yd and Dpd urinary levels and slightly increased post-transplant iPTH. Statistical analyses demonstrated a correlation between Pyd and ALP, Pyd and Dpd, pre- and post-transplant iPTH, and creatinine and ALP. No statistical correlation was found among Pyd and Dpd and other paramet ers of bone metabolism. In the Group A patients, there Was a statistic ally significant correlation between Pyd and ALP, Pyd and Dpd, ALP and post-transplant iPTH, BGP and post-transplant iPTH, and pre- and post -transplant iPTH. In the group B patients, there was a statistically s ignificant correlation between post-transplant iPTH and transplant age only. In conclusion, our results show that urinary cross-links measur ements could be helpful in revealing bone resorption in renal transpla nt patients when usual bone metabolism parameters do not demonstrate h yperparathyroid disease.