Summary:We report on the diagnostic validity of the serum concentrations of the C-terminal propeptide of type I procollagen (a marker of bone formation) and of the urinary excretion of deoxypyridinoline (a marker of bone resorption) in a consecutive series of 89 tumour patients who were routinely examined by 99m Tc-methylene bisphosphonate bone scintigraphy for detection of bone metastases.Z score analysis reveals that the discriminating power of deoxypyridinoline is superior to that of calcium excretion whereas the discriminating power of the C-terminal propeptide concentrations is inferior to that of bone alkaline phosphatase values. Accuracy (as assessed by the area under the receiver-operating characteristic curve) was 0.75 for deoxypyridinoline and 0.82 for the C-terminal propeptide. Combination of both markers did not yield an increase of accuracy (0.82) compared with the determination of the C-terminal propeptide concentrations alone. There was a correlation (r = + 0.398; p < 0.0001) between C-terminal propeptide concentrations and deoxypyridinoline excretion values in the group of 89 patients examined.Further studies should be done to elucidate whether the determination of bone collagen turnover is suitable as a screening procedure for detecting bone metastases.

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