Occult vitamin D deficiency in postmenopausal US women with acute hip fracture

Abstract

Context: Low vitamin D levels may contribute to hip fractures in women, although limited data are available on vitamin D levels in US women admitted with acute hip fractures.

Objective: To determine whether postmenopausal women with hip fractures have low vitamin D and high parathyroid hormone levels compared with nonosteoporotic and osteoporotic women admitted for elective joint replacement.

Design: Comparative case series conducted between January 1995 and June 1998.

Setting and patients: Ninety-eight postmenopausal community-dwelling women with no secondary causes of bone loss admitted for hip replacement, of whom 30 women had acute hip fractures and 68 women were admitted for elective joint replacement. Of the women admitted for elective joint replacement, 17 had osteoporosis and 51 did not. Women with comorbid conditions or who were taking medications that affect bone density and turnover were excluded.

Main outcome measures: Primary measures were levels of vitamin D and parathyroid hormone; secondary measures were body composition and markers of bone turnover.

Results: Women with hip fractures had lower levels of 25-hydroxyvitamin D than women without osteoporosis admitted for elective joint replacement (P = .02) and than women with osteoporosis admitted for elective joint replacement (P = .01) (medians, 32.4, 49.9, and 55.0 nmol/L, respectively; comparisons adjusted for age and estrogen intake). Parathyroid hormone levels were higher in women with fractures than women in the nonosteoporotic control group (P<.001) or than elective osteoporotic women (P = .001) (medians, 5.58, 3.26, and 3.79 pmol/L, respectively; comparisons adjusted for age and estrogen intake). Fifteen patients (50.0%) with hip fractures had deficient vitamin D levels (< or =30.0 nmol/L) and 11 (36.7%) had a parathyroid hormone level greater than 6.84 pmol/L. Levels of N-telopeptide, a marker of bone resorption, were greater in the women with hip fractures than in the elective nonosteoporotic controls (P = .004).

Conclusions: Postmenopausal community-living women who presented with hip fracture showed occult vitamin D deficiency. Repletion of vitamin D and suppression of parathyroid hormone at the time of fracture may reduce future fracture risk and facilitate hip fracture repair. Because vitamin D deficiency is preventable, heightened awareness is necessary to ensure adequate vitamin D nutrition, particularly in northern latitudes.