Cross-linked C-terminal telopeptide of type I collagen in serum before and after treatment with alfacalcidol and calcium carbonate in early and moderate chronic renal failure.

The diagnosis of renal osteodystrophy (RO) in chronic renal failure (CRF) in everyday practice depends on noninvasive methods. Still there is no widely accepted bone resorption marker in RO. The aim of the study was to evaluate the correlation of serum cross-linked C-terminal telopeptide of type I collagen (s-CTx) as the resorption marker with clinical and biochemical data and to evaluate s-CTx level changes after treatment with low dose of alfacalcidol and calcium carbonate. Sixty patients (36 men and 24 women) with creatinine serum level 3.0 +/- 1.5 mg% were examined. The result of s-CTx was normal in 27 patients and increased in 33. There was a significant positive correlation of s-CTx and serum creatinine (p < 0.001), alkaline phosphatase activity (p < 0.05) and duration of CRF (p < 0.05) in men and serum creatinine (p < 0.001) and phosphorus (p < 0.05) in postmenopausal women. Patients with increased s-CTx had significantly higher serum creatinine (p < 0.001), phosphorus (p < 0.01), alkaline phosphatase activity (p < 0.001) and longer duration of CRF (p < 0.001) than patients with normal s-CTx. Next, 25 patients were treated for 6 months with alfacalcidol in dose of 0.25 microg every other day and calcium carbonate in dose of 3.0 microg per day and 25 patients with calcium carbonate only. There was a statistically significant decrease of s-CTx in both groups of patients (p < 0.01). We conclude, that in patients with CRF, s-CTx can be taken as the marker of bone resorption changes after treatment of RO but the value of s-CTx as a diagnostic marker in these patients ought to be evaluated in comparison with histomorphometry.