[Reference values of assayable pyridinolines as markers of bone turn-over]

The authors aimed to identify reference values for pyridine cross-links (HP and LP) in clinically normal populations. These cross-links are thought to be markers of bone resorption and are released by osteoclasts and eliminated in the urine. The normal values reported in the literature vary considerably. For this purpose the authors analysed groups of male and female patients, divided into age brackets, with no apparent bone metabolism disorders. Hydroxylysylpyridinoline (HP) values revealed no statistically significant differences in relation to either sex or age. Lysylpyridinoline (LP) values in subjects aged under 50 showed virtually comparable reference intervals in male and female subjects, whereas patients over 50 showed a different pattern of behaviour. In conclusion it can be said that, once reliable reference values have been identified using a urinary cross-link assay (in particular for LP), it is possible to evaluate bone resorption in postmenopausal women.