Correlation of hemoglobin with osteoporosis in elderly Chinese population: A cross-sectional study

{"Background": "Both osteoporosis (OP) and anemia are highly prevalent in aging populations, yet the relationship between hemoglobin (Hb) and bone mineral density (BMD) remains poorly understood. Animal studies have shown that lower Hb levels are associated with impaired bone turnover and poor bone strength, and some human studies have reported positive associations between Hb and BMD. However, findings have been inconsistent, and few studies have examined this relationship specifically in the Chinese elderly population. This study aimed to evaluate the correlation between Hb levels and OP in a Chinese cohort aged 55\u201385 years.", "Methods": "This cross-sectional study enrolled 1,068 individuals (449 males, 619 females) aged 55\u201385 years from June 2019 to November 2019 at two communities in Putuo District, Shanghai, China. Inclusion criteria were age 55\u201385 years, BMI 18.5\u201335.0 kg/m\u00b2, normal liver and renal function, and no use of drugs affecting bone metabolism. Exclusion criteria included history of gastrointestinal surgery, hemoglobinopathies, major cardiovascular/cerebrovascular diseases, autoimmune diseases, malignant tumors, and unhealthy lifestyle habits. Data on demographics and clinical characteristics were collected. Complete blood count was measured using an automatic blood analyzer (SYSMEX XN3000). BMD at lumbar spine L1\u2013L4, femur neck, and total hip was measured by dual-energy X-ray absorptiometry (DXA, HOLOGIC Discovery; coefficient of variation <1%). Thoracolumbar spine X-rays were evaluated using the Genant visual semi-quantitative method. OP was diagnosed according to the AACE/ACE primary osteoporosis guideline (2020). Participants were divided into sex-specific Hb quartiles. Univariate and multivariate linear regression analyses evaluated correlations between Hb and BMD T-score. Logistic regression assessed odds ratios (OR) for OP across Hb quartiles, with adjustments for gender, age, BMI (Model 1), plus diabetes mellitus (Model 2), plus lipid profile (Model 3).", "Key Results": "The OP group (n=409) had significantly lower Hb levels compared to the non-OP group (n=659): 137.68 \u00b1 12.35 vs. 145.40 \u00b1 13.15 g/L (p<0.001). The OP group was older (68.81 \u00b1 4.96 vs. 67.81 \u00b1 5.57 years, p=0.004), had lower BMI (23.15 \u00b1 3.88 vs. 24.40 \u00b1 3.47 kg/m\u00b2, p<0.001), lower prevalence of diabetes mellitus (20.54% vs. 30.05%, p=0.001), and higher rate of morphological vertebral fracture (78.85% vs. 45.22%, p<0.001). Multivariate linear regression showed Hb was positively associated with BMD T-score at all sites after adjusting for gender, age, BMI, DM, and vertebral fracture: lumbar spine L1\u2013L4 (\u03b2=0.008, p=0.035), femur neck (\u03b2=0.006, p=0.005), and total hip (\u03b2=0.007, p=0.007). Logistic regression demonstrated that the OR for OP decreased with increasing Hb quartiles. In the fully adjusted model (Model 3: gender, age, BMI, DM, TG, TC, LDL-C, HDL-C), compared to the lowest Hb quartile, the OR for OP in the highest quartile was 0.62 (95% CI: 0.41\u20130.92, p=0.019) overall. For women, the highest quartile had OR 0.52 (95% CI: 0.32\u20130.86, p=0.010); for men, the third quartile had OR 0.42 (95% CI: 0.19\u20130.89, p=0.024). For one SD increase in Hb, the adjusted OR for OP was 0.75 (95% CI: 0.63\u20130.89, p=0.001) overall, 0.73 (95% CI: 0.57\u20130.92, p=0.008) in women, and 0.74 (95% CI: 0.57\u20130.96, p=0.025) in men.", "Clinical Implications": "This study demonstrates a significant positive correlation between hemoglobin levels and bone mineral density in the elderly Chinese population, with lower Hb levels associated with higher odds of osteoporosis. The findings suggest that clinicians should monitor BMD closely in elderly patients with anemia or low hemoglobin levels. However, as a cross-sectional study, causality cannot be established, and whether Hb level can be used to predict OP risk requires further longitudinal studies. The authors note limitations including the inability to establish cause-and-effect relationships, lack of adjustment for nutritional status and exercise levels, and the need for randomized controlled trials to determine whether increasing Hb through nutritional supplementation could delay bone loss."}