Bone mineral density and serum levels of aminoterminal propeptides and cross-linked N-telopeptides of type I collagen in elderly men

Serum levels of aminoterminal extension propeptides (PINP), the carboxyterm inal telopeptide (ICTP), and the cross-linked N-telopeptides (NTx) of type I collagen were determined in 78 healthy, elderly men aged 76 +/- 5 years i n 1993 and 1996 and compared with bone mineral density (BMD) measurements o f their lumbar spine, femoral neck, and total body regions made using dual X-ray absorptiometry. Compared with II men who had normal lumbar spine (SBM D) and femoral neck BMD (NBMD), 13 of the subjects with SBMD and NBMD class ified as osteopenic by t-score criterion had higher mean serum levels of PM P and alkaline phosphatase activity, but these increases were not statistic ally significant at the 95% confidence interval, In osteopenic men, a corre lation between SBMD and NTx was detected (r = -0,66,p = 0.01), Within the e ntire population, the serum NTx level correlated with NBMD (r = -0.26,p < 0 .05) and PINF (r = +0.63, p < 0.0001), and the change-in the circulating co ncentration of PINP over the 3 year interval correlated with the magnitude of change in total body BMD (I = -0.28, p = 0.02), NBMD (r = -0.24,p = 0,05 ), and SBMD (r = -0.36, p = 0.03) as well as with the change in serum NTx l evels (r = 0.43, p < 0.001), The change in the circulating ICTP level was a lso related to the change in NBMD (r = -0.24, p = 0.01). Together, weight a nd the serum PINP level accounted for 25% of total body BMD variance in eld erly men, These results indicate that larger populations of men and women s hould be screened over longer time intervals to explore the value of serial measurement of serum collagen metabolites in predicting bone loss in the s pine and hip. (C) 2000 by Elsevier Science Inc. All rights reserved.