The effects of testosterone administration on muscle areas of the trunk and pelvic floor in hysterectomized women with low testosterone levels: proof-of-concept study

Abstract

Objective: The aim of this study was to determine the effect of testosterone administration on trunk and pelvic floor muscle area in women with low testosterone levels.

Methods: Participants were hysterectomized women with total testosterone<31 ng/dL and/or free testosterone<3.5 pg/mL; participating in the Testosterone Dose Response in Surgically Menopausal Women (TDSM) trial. All participants received a standardized transdermal estradiol regimen during the 12-week run-in period, and were then randomized to receive weekly intramuscular injections of placebo, or 3, 6.25, 12.5, or 25 mg testosterone enanthate for 24 weeks. Muscle areas of the trunk and pelvis were measured at baseline and end of treatment using 1.5 Tesla magnetic resonance imaging. Total and free testosterone levels were measured by liquid chromatography-tandem mass spectrometry and equilibrium dialysis, respectively. Testosterone effect on muscle areas was analyzed using linear regression models.

Results: A total of 24 women who had available baseline and posttreatment magnetic resonance imaging were included in the analysis. Increased cross-sectional areas of the paraspinal, psoas, and abdominal wall muscles were seen after testosterone administration. The estimated mean change (95% CI; P value) between treatment groups was 4.07 cm (1.26-6.88; P = 0.007) for paraspinal, 1.60 cm (0.10-3.09; P = 0.038) for psoas major, and 7.49 cm (1.96-13.02; P = 0.011) for abdominal wall muscles. Increases in psoas muscle area were significantly associated with changes in free testosterone concentrations. No significant changes in obturator internus and pelvic floor muscle areas were observed.

Conclusion: Short-term testosterone administration in women with low testosterone levels was associated with increased trunk muscle area.

Trial registration: ClinicalTrials.gov NCT00494208.

Conflict of interest statement

Conflicts of interest/financial disclosures: Dr. Bhasin has received research grant support from Abbvie Pharmaceuticals and Eli Lilly and Co. for investigator-initiated research; these research grants are managed by the Brigham and Women’s Hospital and are unrelated to this study. No other potential conflict of interest relevant to this article was reported. Dr. Blomqvist is Cofounder of Collective Minds Radiology.

Figures

Figure 1.. T1-weighted Magnetic Resonance Images of areas Measured

A) Muscle areas at 3rd lumbar vertebrae, abdominal wall (AW), psoas major (PM), paraspinal muscles (PS), B) The obturator internus muscles, C) The pelvic floor muscles.

Figure 2.. Change in Trunk and Pelvic Muscle Area by Treatment Group

Boxplots present the mean and 95% confidence interval of 24 weeks changes from baseline in trunk and pelvic muscle areas by treatment group. P-values are extracted from linear regression models adjusted for baseline muscle area and BMI.

Figure 3.. Change in trunk muscle areas with change in serum testosterone levels

Scatter diagram of serum testosterone change on trunk muscle areas after 24 weeks in participants treated with testosterone. P-values and R2represent association between trunk muscle areas and serum testosterone calculated from simple linear regression models. T, testosterone.