Urinary Bone Resorption Markers (Deoxypyridinoline and C-Terminal Telopeptide of Type I Collagen) in Healthy Persons, Postmenopausal Osteoporosis and Patients with Type I Diabetes

Abstract

Deoxypyridinoline (DPD) is a derivative of hydroxypyridinium, which is released during bone resorption into the blood stream and is eliminated unmodified with urine. A further collagen-derived marker of bone resorption is the C-terminal telopeptide of type I collagen (beta-CTX-I, here abbreviated as CTX), which is released in bone resorption and almost entirely excreted by the kidneys. The aim of our study was to investigate different well-described patient groups as well as normal probands in view of differences and expected correlations of these two parameters: patients with insulin-dependent diabetes mellitus, postmenopausal women with osteoporosis and healthy control persons. We used a solid-phase chemiluminescence enzyme immunoassay (Pyrilinks D-IMMULITE) for urinary DPD measurement and for the assessment of urinary CTX we used a quantitative ELISA (Osteometer Biotec A-S, CrossLaps ELISA). We found a highly significant correlation between both parameters in the group of healthy persons (r = 0.75, p < 0.05, n = 28) as well as in the group of patients with diabetes mellitus type I (r = 0.79, p < 0.05, n = 65). Also, a significant correlation was observed between DPD and CTX (r = 0.583, p < 0.05, n = 88) in the group of female osteoporotic patients. Despite good correlations between DPD and CTX in all of the investigated groups, these urinary markers were of limited diagnostic significance in the group of postmenopausal osteoporosis due to a wide spread (few patients showed concentrations above the range of healthy persons) in this newly diagnosed drug-naïve patient collective.