Beyond Estrogen: Distribution and Hormonal Correlates of Serum Testosterone Among Postmenopausal U.S. Women, NHANES 2011–2016 and 2021–2023

Background/Objectives: Lower circulating testosterone concentrations in postmenopausal women have been associated with adverse sexual, skeletal, and metabolic outcomes, yet population-level prevalence estimates remain inconsistent. In the absence of universally accepted diagnostic thresholds for androgen deficiency in women, interpretation of serum testosterone concentrations remains variable. This study aimed to describe the distribution of serum total testosterone and to evaluate demographic and hormonal correlates among physiologic postmenopausal women in the United States. Methods: This cross-sectional study analyzed women meeting criteria for physiologic menopause from the 2011–2016 and 2021–2023 National Health and Nutrition Examination Survey (NHANES) cycles. Participants using androgenic medications were excluded. Because no universally accepted diagnostic threshold exists for testosterone deficiency in women, serum total testosterone <30 ng/dL was used as an operational, population-based reference point, with <20 ng/dL evaluated as a sensitivity threshold. Survey-weighted analyses characterized the cohort and examined associations between testosterone concentrations below the <30 ng/dL operational threshold and demographic and hormonal variables using logistic regression. Results: Among 2707 postmenopausal women, the weighted mean total testosterone was 25.2 ± 1.1 ng/dL. Using operational, distribution-based thresholds, 56.0% of women had testosterone concentrations <20 ng/dL and 79.9% had concentrations <30 ng/dL (Rao–Scott χ2, p < 0.001). In the weighted distribution, both thresholds lay above the weighted median, with 30 ng/dL exceeding the 75th percentile. The proportion of women with testosterone concentrations below the <30 ng/dL threshold differed significantly by race/ethnicity (p < 0.01) and age group (p < 0.01), highest among Non-Hispanic Asian (87.7%) and Mexican American (89.4%) women and lowest among Non-Hispanic Black women (75.5%). In multivariable models, higher sex hormone binding globulin (SHBG) (adjusted OR = 0.720; 95% CI: 0.633–0.820; p < 0.001) and higher estradiol (adjusted OR = 0.577; 95% CI: 0.389–0.856; p < 0.05) were independently associated with lower odds of testosterone concentrations below the <30 ng/dL threshold. Conclusions: Testosterone concentrations below operational thresholds are highly prevalent among U.S. postmenopausal women, although estimates vary depending on the cutoff applied. Higher SHBG and estradiol levels were inversely associated with testosterone concentrations below these thresholds, underscoring the physiologic interrelationship of these hormones in postmenopausal women. These findings highlight the need for standardized, population-specific reference thresholds and clearer clinical frameworks for interpreting androgen levels in women.