Association between inflammatory markers and bone mineral density: a cross-sectional study from NHANES 2007-2010

Monocyte-to-lymphocyte ratio (MLR), neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) are acknowledged as novel inflammatory markers. However, studies investigating the correlation between inflammatory markers and osteoporosis (OP) remain scarce. We aimed to investigate the relationship between NLR, MLR, PLR and bone mineral density (BMD).

A total of 9054 participants from the National Health and Nutrition Examination Survey were included in the study. MLR, NLR and PLR were calculated for each patient based on routine blood tests. Given the complex study design and sample weights, the relationship between inflammatory markers and BMD was evaluated through weighted multivariable-adjusted logistic regression and smooth curve fittings. In addition, several subgroup analyses were conducted to assess the robustness of the outcomes.

This study observed no significant relationship between MLR and lumbar spine BMD (P = 0.604). However, NLR was positively correlated with lumbar spine BMD (β = 0.004, 95% CI: 0.001 to 0.006, P = 0.001) and PLR was negatively linked to lumbar spine BMD (β = - 0.001, 95% CI: - 0.001 to - 0.000, P = 0.002) after accounting for covariates. When bone density measurements were changed to the total femur and femoral neck, PLR was still significantly positively correlated with total femur (β = - 0.001, 95% CI: - 0.001, - 0.000, P = 0.001) and femoral neck BMD (β = - 0.001, 95% CI: - 0.002, - 0.001, P < 0.001). After converting PLR to a categorical variable (quartiles), participants in the highest PLR quartile had a 0.011/cm² lower BMD than those in the lowest PLR quartile (β = - 0.011, 95% CI: - 0.019, - 0.004, P = 0.005). According to subgroup analyses stratified by gender and age, the negative correlation with PLR and lumbar spine BMD remained in males and age < 18 groups, but not in female and other age groups.

NLR and PLR were positively and negatively correlated with lumbar BMD, respectively. And PLR might serve as a potential inflammatory predictor of osteoporosis outperforming MLR and NLR. The complex correlation between the inflammation markers and bone metabolism requires further evaluation in large prospective studies.