Tartrate-resistant acid phosphatase 5b and its correlations with other markers of bone metabolism in kidney transplant recipients and dialyzed patients.

PURPOSE Renal osteodystrophy is a common complication of chronic renal failure and renal replacement therapy. Successful kidney transplantation reverses many of these abnormalities, however, the improvement is often incomplete. The osteoclast specific 5b isoform of tartrate-resistant acid phosphatase (TRAP) 5b has recently been proposed a specific and sensitive marker of bone resorption. The aim of the study was to assess correlations of TRAP 5b with markers of bone resorption and formation in kidney transplant recipients, hemodialyzed and peritoneally dialyzed patients and healthy volunteers. MATERIAL AND METHODS We assessed PTH, markers of bone formation-alkaline phosphatase and its bone isoform, osteocalcin, markers of bone resorption--procollagen type I carboxy-terminal extension peptide, procollagen type I cross-linked carboxy-terminal telopeptide, serum CrossLaps-Ctx, beta2-microglobulin and urinary deoxypyridynoline (DPD), expressed as DPD/creatinine ratio. (BMD) bone mineral density measurements were determined for femoral neck and lumbar spine (L2-L4) using DEXA. RESULTS In dialyzed patients markers of bone formation and resorption were significantly higher than in healthy volunteers, whereas in kidney transplant recipients these disturbances were less pronounced. TRAP 5b correlated positively with age and mainly with markers of bone resorption in kidney transplant recipients, dialyzed patients and healthy volunteers. TRAP 5b did not correlate with BMD in any groups studied. CONCLUSION Since TRAP 5b correlated mainly with markers of bone resorption, it may serve as a new additional marker of bone resorption in the assessment of renal osteodystrophy.