Association of sex hormones with sexual function, vitality, and physical function of symptomatic older men with low testosterone levels at baseline in the testosterone trials

Abstract

Context: The prevalence of sexual dysfunction, low vitality, and poor physical function increases with aging, as does the prevalence of low total and free testosterone (TT and FT) levels. However, the relationship between sex hormones and age-related alterations in older men is not clear.

Objective: To test the hypotheses that baseline serum TT, FT, estradiol (E2), and sex hormone-binding globulin (SHBG) levels are independently associated with sexual function, vitality, and physical function in older symptomatic men with low testosterone levels participating in the Testosterone Trials (TTrials).

Design: Cross-sectional study of baseline measures in the TTrials.

Setting: The study was conducted at 12 sites in the United States.

Participants: The 788 TTrials participants were ≥ 65 years and had evidence of sexual dysfunction, diminished vitality, and/or mobility disability, and an average of two TT < 275 ng/dL.

Interventions: None.

Main outcome measures: Question 4 of Psychosocial Daily Questionnaire (PDQ-Q4), the FACIT-Fatigue Scale, and the 6-minute walk test.

Results: Baseline serum TT and FT, but not E2 or SHBG levels had small, but statistically significant associations with validated measures of sexual desire, erectile function, and sexual activity. None of these hormones was significantly associated within or across trials with FACIT-Fatigue, PHQ-9 Depression or Physical Function-10 scores, or gait speed.

Conclusions: FT and TT levels were consistently, independently, and positively associated, albeit to a small degree, with measures of sexual desire, erectile function, and sexual activity, but not with measures of vitality or physical function in symptomatic older men with low T who qualified for the TTrials.

Trial registration: ClinicalTrials.gov NCT00799617.

Figures

Figure 1.

Association of total testosterone (TT) with sexual function parameters at the baseline visit in men enrolled in the Sexual Function Trial of the TTrials. A, Positive association of TT (unadjusted) with sexual desire [Derogatis Inventory of Sexual Function (DISF)] (unadjusted); B, adjusted TT with adjusted DISF; C, erectile function [International Index of Erectile Function (IIEF) (unadjusted) with total testosterone (unadjusted); D, adjusted T with IIEF; E, TT (unadjusted) with sexual activity [Psychosexual Daily Questionnaire, Question 4 (PDQ-Q4) (unadjusted); and F, adjusted TT with adjusted PDQ-Q4. The adjustments were made for the potential confounders of age, hypertension, diabetes, waist circumference and BMI. The adjusted values shown are those that remained after removing the effects due to the potential confounders.

Figure 2.

Association of vitality and depression with total testosterone at the baseline visit in men enrolled in the Vitality Trial of the TTrials. A, Association of total testosterone (TT) (unadjusted) with vitality assessed by the FACIT-Fatigue scale (unadjusted); B, adjusted FACIT-Fatigue with adjusted TT; C, TT (unadjusted) with depression as assessed by the PHQ-9 (unadjusted); and D, adjusted TT with adjusted PHQ-9. The adjustments were for the potential confounders of age and BMI. The adjusted values shown are those that remained after removing the effects due to the potential confounders.

Figure 3.

Association of total testosterone (TT) with physical function parameters at the baseline visit in men enrolled in the Physical Function Trial of the TTrials. A, Association of TT (unadjusted) with gait speed (unadjusted); B, adjusted TT with adjusted gait speed; C, TT (unadjusted) with the physical function domain of the SF-36 (PF10) (unadjusted); and D, adjusted TT with the adjusted PF10. The adjustments were for age and BMI. The adjusted values shown are those that remained after removing the effects due to the potential confounders.