BONE-RESORPTION IN HEALTHY AND OSTEOPOROTIC POSTMENOPAUSAL WOMEN - COMPARISON MARKERS FOR SERUM CARBOXY-TERMINAL TELOPEPTIDE OF TYPE-I COLLAGEN AND URINARY PYRIDINIUM CROSS-LINKS

We compared two highly specific markers for bone resorption-pyridinium cross-links (pyridinoline (PYR) and deoxypyridinoline (DPR)) in urine and carboxy-terminal telopeptide of type I collagen (ICTP) in serum - in 63 healthy postmenopausal women and 63 women with osteoporosis cha racterized by more bone resorption than bone formation. The ICTP. PYR and DPR levels were all higher, by 24% (p = 0.001), 16% (p = 0.05) and 25% (p = 0.004), respectively, in the osteoporotic women. For the mer ged groups, there were significant correlations between serum ICTP con centration and urinary PYR (r = 0.667, p < 0.0001) and DPR (r = 0.452, p < 0.0001) excretion; for the osteoporotic and normal women separate ly, the r values were 0.73 (p < 0.01) and 0.45 (p < 0.01) for PYR and 0.51 (p < 0.01) and 0.22 (p = 0.08) for DPR versus ICTP respectively. Weak correlations in linear regression between ICTP and various indice s of bone formation (osteocalcin, bone-specific alkaline phosphatase a nd carboxy-terminal propeptide of type I procollagen) disappeared when the correlation between ICTP and pyridinolines was accounted for by c alculation of partial correlation coefficients in multiple regression analysis. Serum ICTP concentration appears to discriminate between gro ups of normal and osteoporotic women as well as urinary pyridinium cro ss-links, which is thus far the most sensitive method for assessing bo ne resorption.