IMMUNOASSAY OF PYRIDINOLINE CROSS-LINK EXCRETION IN NORMAL ADULTS ANDIN PAGETS-DISEASE

A new immunoassay (ELISA) based on an antiserum that preferentially re cognizes the free form of the pyridinoline (Pyr) crosslink was used to assess the urinary excretion of Pyr in a large normal sample of the p opulation comprising 236 men and 193 women 30-90 years of age. Urinary Pyr increased significantly with age in both sexes. In women Pyr was higher than in men (57 +/- 21 versus 46 +/- 17 nmol/mmol creatinine, p < 0.001), and the menopause was reflected by a mean 37% increase, fro m an average 43 to 59 nmol/mm creatinine (p < 0.001). In 52 patients w ith active Paget's disease of bone, Pyr excretion was markedly increas ed (206 +/- 160 nmol/mmol creatinine, p < 0.001 versus controls) and d ecreased by 71% after 3 days of IV treatment with the bisphosphonate p amidronate. Free Pyr measured by the ELISA and the total urinary excre tion measured by HPLC were highly correlated both in normals (n = 74, r = 0.83, p < 0.001) and in Pagetic patients (n = 20, r = 0.93, p < 0. 001). The mean intra- and interassay coefficients of variation of the ELISA were below 9 and 15%, respectively. It is concluded that this ne w convenient immunoassay of Pyr should be valuable for the clinical in vestigation of patients with osteoporosis and other metabolic bone dis eases.