[Bone metabolism as assessed with selected markers of bone turnover as well as densitometry analysis in patients after successful kidney transplantation].

The degree of advancement as well as symptoms of renal osteodystrophy improve significantly in patients after successful kidney transplantation; however bone pathology is still present even after many post-transplant years. The aim of this study was to analyze the bone densitometry in patients during different periods after kidney transplantation and to assess bone metabolism using selected biochemical markers of bone turnover in comparison to healthy controls. Study population consisted of 73 patients of mean age 41.7 +/- 12.6 years (27F, 46M) mean 34 +/- 42 months after kidney transplantation. Mean period of maintenance dialysis prior to surgery was 28.6 +/- 20.3 months. We also analyzed age- and sex-matched control group of 24 subjects. Three-point densitometry was performed with DEXA technique. Serum levels/activity of osteocalcin, C-terminal propeptide of procollagen type I (PCTP), alkaline phosphatase (AP) and its bone-specific isoform (BAP) as well as desoxypiridine (DPD) urine level were analyzed as markers of bone turnover. Serum levels/activity of all mentioned parameters were significantly increased (p < 0.001) and urine DPD--significantly decreased (p < 0.05) in patients as compared to controls. Based on DEXA technique 26% of patients were categorized as having osteoporosis, 32.9%--osteopenia and 41.1% as normal in bone densitometry. Patients with diagnosed osteoporosis spent significantly longer time with functioning graft as compared to those with normal densitometry. In addition, subjects with osteoporosis were characterized by significantly higher serum level of osteocalcin as compared to those with osteopenia and normal DEXA (42.5 +/- 19.9 vs 26.6 +/- 15 ng/ml and 42.5 +/- 19.9 vs 30.2 +/- 104 ng/ml, respectively; p < 0.05). Identical relationship was also observed for serum PTH (128 +/- 42 vs 77.2 +/- 30.4 pg/ml and 128 +/- 42 vs 81.2 +/- 232 pg/ml, respectively; p < 0.001). There was also significant difference in PCTP level in all analyzed groups (203 +/- 85, 171 +/- 69 and 137 +/- 40 ng/ml in subjects with osteoporosis, osteopenia and normal; p < 0.05 for all differences). BAP activity reduction was observed only in the latter group of patients. Results of our study led us to conclude that the prevalence of osteoporosis and osteopenia in three-point densitometry among patients with functioning graft is high. Increased serum levels/activity of osteocalcin, PCTP, AP and BAP with concomitant decrease of urine DPD elimination suggest the predominance of bone formation over the bone resorption process.