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Reproductive Endocrinology

SUN-138 - Low free testosterone directly measured using equilibrium dialysis is associated with worse sexual function in community-dwelling men from the European Male Ageing Study (EMAS)

Sunday, June 14, 2026
9:00 AM - 4:00 PM CT


Introduction: The association between circulating testosterone (T) levels and male sexual function was found to be stronger for free T than for total T. However, most studies have relied on calculated free T rather than directly measured free T (mFT).

Objective: To investigate the association between mFT and sexual function in community-dwelling men.

Methods: The European Male Ageing Study assessed sexual function (frequency of sexual thoughts, sexual intercourse, petting, morning erection and orgasm, erectile (dys)function and sexual desire) using a validated questionnaire. mFT was measured by liquid chromatography–tandem mass spectrometry following equilibrium dialysis in an EMAS subset (n = 526). Proportional ordinal logistic regression and restricted cubic spline regression, adjusted for age, BMI and study center, were used to investigate sexual function outcomes in relation to mFT.

Results: The mean age in this EMAS subset was 70.5 ± 8.5 years, with a mean body mass index of 27.3 ± 3.3 kg/m² and mean mFT of 198 ± 82 pmol/L. In proportional ordinal logistic regression models, lower mFT was significantly associated with erectile dysfunction (odds ratio (OR) per 10 pmol/L decrease 1.04 [95% confidence interval (CI) 1.01 - 1.06], p < 0.01), fewer sexual intercourse (OR 1.03 [1.00 - 1.06], p < 0.05), lower frequency of orgasm (OR 1.03 [1.01 - 1.06], p < 0.05) and reduced sexual desire (OR 1.03 [1.01 - 1.05], p < 0.05). Consecutive restricted cubic spline models suggested a nonlinear association between mFT and both erectile function and orgasm frequency. The risk of erectile dysfunction increased with a decrease in mFT: values below a threshold of 163 pmol/L were associated with a markedly steeper increase in the predicted probability of worse erectile function. Similarly, mFT values below 138 pmol/L were associated with a sharp increase in the predicted probability of decreased orgasm frequency.

Conclusion: In community-dwelling men, lower mFT was associated with worse erectile function, fewer attempts at sexual intercourse, reduced orgasm frequency, and lower sexual desire, with evidence of non-linear thresholds for erectile dysfunction and orgasm frequency at 163 and 138 pmol/L, respectively.

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