Association between sex hormone levels and high-sensitivity C-reactive protein in older adults aged 65 years and above in 18 longevity areas in China

Objective: To investigate the association between levels of follicle-stimulating hormone (FSH), testosterone (T), and estradiol (E2) and high-sensitivity C-reactive protein (hs-CRP) in participants aged ≥65 years residing in 18 longevity regions of China. Methods: Based on the 2021 China Healthy Ageing and Biomarkers Cohort Study, 5 556 participants were enrolled. Plasma FSH, T, and E2 levels were measured using chemiluminescent immunoassay, while hs-CRP levels were determined via latex immunoturbidimetry. Multiple linear regression models were used to analyze the change in hs-CRP concentration (β value) per 1 standard deviation increase in sex hormones, along with its 95%CI. Restricted cubic spline models were applied to explore nonlinear associations, and analyses were stratified by sex. Results: The age of male participants was (82.9±10.6) years. Median sex hormone levels were as follows: male: FSH 22.3 IU/L, T 411.4 ng/dl, E2 30.5 pg/ml; female: FSH 77.4 IU/L, T 22.1 ng/dl (E2 detection rate in females was only 10.6%). Multiple linear regression model revealed that after adjusting for confounding factors: for each one-standard-deviation increase in male T (166.0 ng/dl), hs-CRP decreased by 0.290 mg/L on average; β (95%CI)=-0.290 (-0.340 - -0.231); for each standard deviation increase in E2 (10.8 pg/ml), hs-CRP decreased by 0.124 mg/L on average, β (95%CI)=-0.124 (-0.171 - -0.067). For each standard deviation increase in female T (44.5 ng/dl), hs-CRP decreased by 0.051 mg/L on average, β (95%CI)=-0.051 (-0.098 - -0.004). Neither male nor female FSH was statistically associated with hs-CRP. Restricted cubic spline analysis revealed a negative nonlinear association between T in both sexes and hs-CRP (all P for nonlinear <0.001); male E2 showed a negative association with hs-CRP (P for overall <0.001). Conclusion: Among participants aged ≥65 years in 18 longevity regions of China, male T and E2 were negatively associated with hs-CRP. Female T was also negatively associated with hs-CRP.