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 (r2 = 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.