Evaluation of bone turnover in type I osteoporosis using biochemical markers specific for both bone formation and bone resorption.
The aims of the study were to evaluate the use of bone-specific biochemical markers of turnover in type I osteoporosis, to test for evidence of heterogeneity of bone turnover in this condition, and to attempt to devise an 'uncoupling index' by using the relationship between bone-specific biochemical markers of bone formation and bone resorption. In women with type I osteoporosis (mean age 64 years, SD 5; n = 63) the mean level of serum osteocalcin, a specific biochemical marker of bone formation, was 9.9 ng/ml (SD 2.0), which was higher than the level in normal postmenopausal women (mean age 65 years, SD 6; n = 8.9 ng/ml (SD 2.0; p < 0.01). The variance of serum osteocalcin levels in the two groups was similar. Compared with this 11% increase in the biochemical marker for bone formation, the markers of bone resorption, total urinary deoxypyridinoline (bone-specific), pyridinoline and hydroxyproline were increased by 40% (p < 0.0001), 61% (p < 0.0001) and 25% (p < 0.01), respectively. Furthermore, these biochemical markers of bone resorption had greater variance in women in type I osteoporosis than in the normal postmenopausal women (p < 0.01). The urinary excretion of the free crosslinks deoxypyridinoline, pyridinoline and glycosylated pyridinoline were increased by 26% (p < 0.001), 17% (p < 0.01) and 13% (NS) respectively. An 'uncoupling index' was calculated for the difference between urinary deoxypyridinoline and serum osteocalcin using the results from the normal women and expressed as z-scores. We conclude that the pyridinium crosslinks of collagen enable better discrimination between normal and osteoporotic women than does hydroxyproline.(ABSTRACT TRUNCATED AT 250 WORDS)
Eastell
R
R
Department of Human Metabolism and Clinical Biochemistry, University of Sheffield, UK.
Robins
S P
SP
Colwell
T
T
Assiri
A M
AM
Riggs
B L
BL
Russell
R G
RG
D000368:Aged; D000596:Amino Acids / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D001846:Bone Development; D001862:Bone Resorption / Q000097:blood / Q000652:urine*; D005260:Female; D006801:Humans; D006909:Hydroxyproline / Q000652:urine*; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000652:urine*; D017698:Postmenopause / Q000097:blood / Q000652:urine*
D000596:Amino Acids; D015415:Biomarkers; D015675:Osteocalcin; C015484:pyridinoline; C036020:deoxypyridinoline; D006909:Hydroxyproline