PICP as bone formation and NTx as bone resorption marker in patients with chronic renal failure.

Unlabelled: Renal bone disease which develops in patients with chronic renal failure (CRF) is not a uniform metabolic disorder. Although bone histomorphometry is accepted to be the gold standard for characterizing the state of disease progression, the techniques involved are cumbersome and expensive so that it cannot be used routinely. As a result, numerous biochemical markes have been developed to measure bone formation and resorption. The purpose of this study was to evaluate the suitability of procollagen type-I C-terminal peptide (PICP) in serum as an indicator of bone formation and cross-linked amino-terminal telopeptide of type I collagen (NTx) in urine as an indicator of bone degradation processes, and to investigate their relation to histomorphometric and other biochemical parameters. 77 patients with CRF and 49 patients on intermittent hemodialysis treatment (DT) were investigated. PICP was measured in serum and NTx in urine. In addition, iPTH, phosphate, calcium, alkaline phosphatase (APH), osteocalcin and creatinine in serum were determined. Bone biopsies were obtained from the anterior, superior iliac crest, and the histomorphometric parameters were measured and expressed according to the standardized nomenclature. Patients with CRF and DT had significantly higher PICP and NTx levels as compared to controls. In the CRF group significant correlations could be obtained between PICP and histomorphometric parameters of bone formation as well as between NTx and histomorphometric indices of bone resorption. In this group, PICP levels were positively correlated to iPTH, phosphate and creatinine levels and negatively to calcium concentrations. Furthermore, there were significant correlations between NTx values and those of both iPTH and APH. In the group of dialysis patients, levels of PICP and NTx did not correlate with any of the histomorphometric parameters or the classical humoral markers.

Conclusions: The results suggest that PICP as bone formation and NTx as bone resorption markers are of potential use for screening bone turnover in predialysis chronic renal failure patients. But in patients undergoing dialysis, neither PICP nor NTx yielded any substantial information as noninvasive markers of bone histology.