Beta 2-microglobulin in postmenopausal osteoporosis.

The so-called bone-derived growth factor, or beta 2-microglobulin, has a regulatory function in bone metabolism, stimulating osteoclastic activity. Osteoclastic activity is enhanced in postmenopausal osteoporosis, suggesting that beta 2-microglobulin concentration may also be increased in this disease. beta 2-microglobulin concentration was found to be raised (P < 0.001) in 30 women with postmenopausal osteoporosis as compared with 30 normal women of similar age; tartrate-resistant acid phosphatase concentration also was raised (P < 0.001), and total body bone mineral content was decreased (P < 0.001). Linear regression analysis revealed a highly negative correlation result between total body bone mineral content and beta 2-microglobulin (r = 0.577, P < 0.001), and a positive correlation result between beta 2-microglobulin and tartrate-resistant acid phosphatase concentration (r2 = 0.806, P < 0.001). These findings, and the stimulatory effect of beta 2-microglobulin on osteoclastic and osteoblastic activity, suggest that beta 2-microglobulin may play an important role as a local regulatory factor in the pathogenesis of postmenopausal osteoporosis.