Serum Vitamin D Status Linked to Hip Fracture

Despite unclear mechanism, women with lowest levels may have 71 percent increased risk

TUESDAY, Aug. 19 (HealthDay News) -- In postmenopausal women, low serum 25(OH) vitamin D concentrations are associated with a significantly higher risk for hip fracture, researchers report in the Aug. 19 issue of the Annals of Internal Medicine.

Jane A. Cauley, of the University of Pittsburgh, and colleagues conducted a nested case-control study of 400 women with incident hip fracture and 400 matched controls who were selected from 39,795 postmenopausal women who did not use estrogens or other bone-active therapies and had not had a previous hip fracture.

The researchers found that the risk of hip fracture was significantly higher in women with the lowest concentrations of serum 25(OH) vitamin D -- below 47.5 nmol/L -- than in women with the highest concentrations -- above 70.7 nmol/L (adjusted odds ratio, 1.71). They also found that the risk was independent of the number of falls, physical function, frailty, renal function and sex-steroid hormone levels.

"The mechanism for the association is unclear. C-terminal telopeptide of type I collagen, a marker of bone resorption, tended to be higher among case-patients with the lowest 25(OH) vitamin D concentrations, an association that may be driven by higher parathyroid hormone levels in this group," the authors write. "The increased fracture risk could also be related to impaired muscle strength and balance and poorer physical function, all of which could lead to an increased risk for falls."

Authors of the study report relationships with various pharmaceutical companies.

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