To investigate the ratio of urinary pyridinoline (Pyr) and deoxypyridinoline (Dpyr) in diseases with bone loss, urinary Pyr and Dpyr levels were evaluated in 48 cases of osteoporosis, 8 cases of carcinoma with bone metastasis, 6 cases of rheumatoid arthritis, and 78 healthy volunteers. It was found that urinary Pyr and Dpyr increased significantly as compared to those in the control ( P 0 05), while it was dramatically lower in the patients with carcinoma bone metastasis ( P