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Serum cross-linked n-telopeptides of type 1 collagen (NTx) in patients with solid tumors.

CONTEXT AND OBJECTIVE
Cross-linked N-telopeptides of type I collagen (NTx) increase in concentration in situations in which bone resorption is increased, such as osteoporosis and bone metastasis (BM). We aimed to evaluate the serum concentrations of NTx in a sample of patients with several types of solid tumors.


DESIGN AND SETTING
Cross-sectional analytical study with a control group in a tertiary public hospital.


METHODS
We performed the quantitative enzyme-linked immunosorbent assay (ELISA) on serum NTx levels in 19 subjects without a history of cancer and 62 patients with various solid tumors who had been referred for a bone scan. Three experienced analysts read all bone scans.


RESULTS
The serum NTx levels in patients with cancer and BM, with cancer but without BM and without cancer were 46.77 +/- 2.58, 32.85 +/- 2.05 and 22.32 +/- 2.90 respectively (P < 0.0001). We did not find any significant correlations of serum NTx with age, gender, history of bone pain, tumor type and bone alkaline phosphatase levels. We found a significant correlation between serum NTx and alkaline phosphatase levels (R(2) = 0.08; P = 0.022).


CONCLUSIONS
Serum NTx levels are significantly higher in patients with solid tumors and bone metastases than they are in patients without bone metastases and in normal controls.