Urinary excretion of pyridinium crosslinks of collagen in oophorectomized women as markers for bone resorption.

To detect increased bone resorption in estrogen-deficient women, the urinary excretion of hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP), which are intermolecular crosslinkings of collagen fibers, were measured and their chronological changes were evaluated following oophorectomy. Seventy-five women were divided into three groups; 15 premenopausal women (mean age 44.0 years), 15 postmenopausal women (mean age 54.2 years) and 45 surgically menopausal women who had a normal menstrual cycle before surgery (mean age 42.2 years). There was a significant increase in HP and LP of the postmenopausal women (P < 0.001). In the oophorectomized women, both HP and LP were three times higher than those of premenopausal women within 1 year after oophorectomy, and decreased to the same level of the postmenopause between 2 and 3 years after surgery. In the six oophorectomized women after the administration of estrogen, HP and LP both decreased remarkably in all cases. The present study thus indicates that an increase of bone resorption which was evaluated by urinary HP and LP occurs in the early stage after oophorectomy. It may, therefore, be good to begin estrogen replacement therapy as soon as possible after oophorectomy.