The present study was aimed to clarify whether bone uncoupling occurs in early (3-5 years) natural menopause. Plasma bone specific alkaline phosphatase (bALP) and osteocalcin (OC), as markers of bone formation, urinary free deoxypyridinoline (Dpd) and type I collagen helical peptide, as markers of bone resorption, in addition to circulating insulin-like growth factor-1 (IGF-1) and L2-L4 spine bone mineral density (BMD), were measured concomitantly to serum calcium and phosphate minerals. Vertebral BMD of postmenopausal women (
n = 30) was significantly lower than that of premenopausal controls (
n = 30). All markers of bone turnover, except for bALP, and serum minerals were markedly greater in the postmenopausal group whereas circulating IGF-1 level was lower (
p < 0.01). Bone uncoupling in early menopause was confirmed by a negative uncoupling status index (USI) value, indicating an excess of resorption over formation. The difference between groups was more pronounced for type I collagen helical peptide (+49.4%) than Dpd (+35.9). This new marker of bone resorption correlated better with bone formation (as assessed by OC) and with serum minerals. The study demonstrated that bone formation and resorption increased but did not balance in early untreated postmenopausal women. Helical peptide discriminated better than Dpd early postmenopausal women from control premenopausal women. It was postulated that an alteration in the quality of bone collagen matrix might be involved in postmenopausal bone mineral loss.
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