Red cell distribution width: a potential marker of reduced femoral neck bone mineral density in men and postmenopausal women

Osteoporosis imposes significant burdens. Early detection of high-risk individuals through simple indicators can greatly improve prognosis. Red cell distribution width (RDW), a standard component of a complete blood count, shows promise, yet remains underexplored. This cross-sectional study aimed to investigate the association between RDW and femoral neck and spinal bone mineral density (BMD).

Participants aged 20–79 years from the 2005–2010, 2013–2014, and 2017–2020 cycles of the National Health and Nutrition Examination Survey (NHANES) were included. BMD was measured using dual-energy X-ray absorptiometry (DXA).

A total of 13,029 participants were included, comprising 6684 men, 3238 postmenopausal women, and 3107 premenopausal women, with the sample weighted to represent 98,712,128 people. After adjusting for covariates, RDW exhibited a negative association with femoral neck BMD in both men (β = −0.006; 95% CI: −0.010 to −0.002; p = 0.0053) and postmenopausal women (β = −0.005; 95% CI: −0.010 to −0.000; p = 0.0413). Subgroup and sensitivity analyses supported the robustness of these findings. A negative association between RDW and spinal BMD in men approached significance (β = −0.004; 95% CI: −0.008 to 0.000; p = 0.0557). Persistent trends were observed for RDW with spinal BMD in postmenopausal women and with both femoral neck and spinal BMD in premenopausal women.

Our study suggests a negative association between RDW and femoral neck BMD in both men and postmenopausal women. These findings highlight the potential of RDW as a marker for identifying individuals at higher risk of osteoporosis.