Protein could signal risk of hip fracture

A physician examines a hip bone X-ray. Researchers say high levels of a protein called cystatin C may signal greater risk for hip fracture in older people. (Photo: iStockphoto)

Hip-risk harbinger—A physician examines a hip bone X-ray. Researchers say high levels of a protein called cystatin C may signal greater risk for hip fracture in older people. (Photo: iStockphoto)

A protein called cystatin C has long been used as a marker of kidney function. As kidney function declines, the levels of the protein in blood go up. In recent years, it has also been investigated as a portent of worsening heart health, and even Alzheimer's disease.

Now, study findings from a team with VA and the University of Minnesota suggest the protein may help identify older people at high risk of hip fracture.

The researchers tracked the outcomes of nearly 1,500 women who had given blood samples in the late 1990s as part of an ongoing study on osteoporosis and fractures. The study participants with the highest levels of cystatin C were nearly twice as likely to break a hip in the additional years of follow-up, compared with women with the lowest levels.

Other traditional markers of kidney function—creatinine or glomerular filtration rate—showed no such connection with fracture risk. The cystatin link held true even when researchers adjusted for age, body mass index, and hip bone mineral density.

The study team included researchers at VA's Minneapolis-based Center for Chronic Disease Outcomes Research. Based on the results, they say cystatin C is a "promising biomarker for identification of older adults at high risk of hip fracture."

(Journal of Bone and Mineral Research, online Jan. 8, 2013)