Effect of free androgen index on blood pressure variability and target organ damage in postmenopausal hypertensive women: findings from a cross-sectional study

Objective: The present study investigated the effects of free androgen index (FM) on ambulatory blood pressure (ASP) and target organ function in postmenopausal hypertensive women. Methods: A total of 285 postmenopausal hypertensive women (mean age 54.06 +/- 3.61) were admitted to the Department of Hypertension of Lanzhou University Second Hospital between December 2018 and December 2020. According to the serum FAI level, the participants were divided into a low-FAT (<0.15) group, a medium-FAI (0.15-0.2) group, and a high-FAT (>0.2) group. The relationship of FM with 24-hour ABP, left ventricular mass index (LVMI), and cardio-ankle vascular index (CAVI) was analyzed. Results: The LVMI, CAVI, 24-hour mean systolic blood pressure (SBP), 24-hour SBP coefficient of variation and 24-hour SBP standard deviation, 24-hour SBP average real variation (ARV), and 24-hour diastolic blood pressure (DBP) ARV in high-FM group were significantly higher than those in low- and medium-FM groups (P < 0.05). After adjusting for confounding factors, partial correlation analysis showed that FM was positively correlated with LVMI (r = 0.728, P < 0.001), CAVI (left: r = 0.718, P < 0.001; right: r = 0.742, P < 0.001), 24-hour SBP ARV (r = 0.817, P < 0.001), and 24-hour DBP ARV (r = 0.747, P < 0.001). After adjusting for confounding factors, it was found that LVMI increased by 17.64 g/m(2) for every 1 unit increase in FAI. CAVI also increased by 8.983 for every additional unit of FM. In addition, the results also showed that LVMI and CAVI decreased respectively by 0.198 g/m(2) and 0.009 for every 1 unit increase in sex hormone-binding globulin. Multivariable linear regression showed that FAI was an independent risk factor for 24-hour SBP ARV (OR: 20.416, 95% CI 8.143-32.688, P = 0.001) and 24-hour DBP ARV (OR: 16.539, 95% CI 0.472-32.607, P = 0.044). The results also showed that sex hormone-binding globulin was an independent factor of 24-hour SBP ARV (OR: -0.022, 95% CI -0.044 to 0.000, P = 0.048) and 24-hour DBP-ARV (OR: -0.018, 95% CI -0.029 to -0.008, P = 0.001). Conclusion: Higher serum FM levels in postmenopausal hypertensive women indicate abnormal BP regulation and more serious target organ damage. FM is closely related to 24-hour SBP ARV and 24-hour DBP ARV in postmenopausal hypertensive women.