[Skeletal scintigraph and some bone turnover markers in the diagnosis of renal osteodystrophy in hemodialysis patients].

UNLABELLED

Real osteodystrophy is a spectrum of bone disorders that developing in patients (pts) with chronic renal failure. In the recent years several new biochemical markers of bone turnover have been proposed for the non-invasive evaluation of bone remodeling in hemodialysis (HD) pts The aim of our study was to examine serum concentrations (conc.) of some biochemical parameters of bone turnover and compare them with the results of bone scintigraphy. We measured serum levels of the aminoterminal propeptide of type I procollagen (PINP) as a marker of bone formation, and the serum levels of the pyridinoline cross-linked telopeptide domain of type I collagen (ICTP) as a marker of bone resorption in a group of 71 HD pts (35 male, 36 female) with a mean age 56 years. The mean duration of treatment was 87 months (range 2-302). We have compared these two collagen related peptides with more classical humoral parameters of renal osteodystrophy. For that purpose we measured serum concentrations of: intact PTH (iPTH), osteocalcin (BGP) and hydroxyproline (Hyd). The control group (CG) consisted of 22 healthy subjects, mean age 41 years. Whole-body bone scintigraphy was performed 2.5 hours after injection of 740 MBq MDP99mTc. The quantification of bone images was performed using bone to soft tissue ratio K. The mean conc. of PINP were significantly higher in HD pts than in CG (170.0 +/- 125.4 vs 32.3 +/- 9.3 micrograms/L, p < 0.001). Likewise and mean conc. of ICTP were significantly higher in pts than in CG (53.3 +/- 14.2 vs 2.9 +/- 0.7 micrograms/L, p < 0.001). We observed that mean conc. of iPTH were significantly higher in pts than in CG (575.7 +/- 569.6 vs 32.3 +/- 9.4 pg/ml; p < 0.001). Also the mean conc. of Hyd and BCG were higher than in CG (305.3 +/- 95.3 vs 281.5 +/- 53.9 mumoL, p < 0.05 and respectively 58.6 +/- 27.2 vs 7.4 +/- 2.7 ng/ml, p < 0.001). K ratio was significantly higher in patients than in control group (GK) (3.7 +/- 1.2 vs 2.2 +/- 0.5, p < 0.01). Some significant positive correlations were observed between: PINP and ICTP (r = 0.71, p < 0.000001); between: PTH and PINP (r = 0.83, p < 0.000001) and between: PTH and ICTP (r = 0.49, p < 0.00002). We found significant positive correlation between: BGP and PINP (r = 0.83, p < 0.000001) and between: BGP and ICTP (r = 0.57, p < 0.0001). No correlation was found between serum Hyd levels and other examined biochemical markers of bone turnover in our group of pts. Significant correlations were found also between K ratio on one hand and PINP (p < 0.01, r = 0.575) and BGP (p < 0.01, r = 0.535) levels on the other. The correlation between K ratio and iPTH was slightly significant (p = 0.05, r = 0.462). We did not find any relationship between other parameters.

CONCLUSION

We concluded that PINP, ICTP and semiquantative bone scan evaluation are good diagnostic tools in the process of bone turnover in hemodialysis patients. The long duration of hemodialysis therapy is connected with higher plasma levels of ICTP--marker of bone resorption.