Could an Index Help Identify Women at Risk for Rapid Bone Loss?

An index that quantifies net bone formation vs resorption can be created from bone turnover markers (BTMs) and may help identify women at high risk for bone loss across the menopause transition, according to a new study.

“In this proof-of-concept study, we aimed to develop and test a novel methodology for combining an individual’s measured BTMs (which reflect total bone formation and resorption across the skeleton) to gauge net bone balance,” the researchers said.
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Study participants included community-dwelling women, 42 to 52 years old, premenopausal or early perimenopausal at baseline. The investigators examined the following 2 measures:

• Bone balance index (BBI) created by estimating the relationship between resorption (urinary N-telopeptide) and formation (osteocalcin) markers when the total formation equals the total resorption in 685 women with stable bone mineral density (BMD) (>5 years before the final menstrual period) and applying this relationship to measured BTMs in 216 women beginning to lose bone (≤2 years from final menstrual period);
• Annualized percentage declines over the following 3 to 4 years in the lumbar spine (LS) and femoral neck (FN) BMD.

Adjusting for covariates, the researchers found the BBI to be greater (more favorable) in women with a greater body mass index (P=.03) and lower (less favorable) in women closer to the final menstrual period (P =.007). Each standard deviation unit decrement in BBI was associated with 0.27%/year faster LS BMD decline (P =0.04) and a 38% higher odds of faster-than-average loss of LS bone mass (P =.008; C statistic, 0.76). They did not see BBI associated with decline in FN BMD, and urinary N-telopeptide alone was not linked with either LS or FN BMD decline.

“A potentially useful index of whole-skeleton bone balance can be created by referencing currently measured BTMs against an estimate of the relationship between resorption and formation markers in a state of whole-skeleton balance (when total formation equals total resorption),” the researchers concluded.

“We still need to test whether this index predicts bone mineral density in older postmenopausal women and whether it is useful for predicting fractures,” added lead study Albert Shieh, MD, in the Division of Endocrinology, Diabetes, and Hypertension at the David Geffen School of Medicine, University of California, Los Angeles.

—Mike Bederka

Reference:

Shieh A, Han W, Ishii S, Greendale GA, Crandall CJ, Karlamangla AS. Quantifying the balance between total bone formation and total bone resorption: an index of net bone formation [published online June 23, 2016]. J Clin Endocrinol Metab. doi:10.1210/jc.2015-4262.