June 14, 2005
Image of Testosterone

Men who complain of irritability, fatigue, and loss of libido—characteristics of andropause, a male version of menopause—are increasingly turning to testosterone replacement therapy. First reported in the mid-40s, research on this little known condition is intensifying with clinical and drug trials in progress.

MOTW update:
February 5, 2024

Testosterone1 is the primary male sex hormone, the shortness of which in older men can cause fatigue, low energy, and loss of libido.

In January, Martha E. Stone, Max B. Kelz, and Alex Proekt at the University of Pennsylvania (Philadelphia) and collaborators there and at the University of Michigan (Ann Arbor) and Washington University (St. Louis) reported that testosterone is primarily responsible for the difference between male and female behavior under general anesthesia. In a mouse study, the researchers found that, at equal brain concentrations of the inhaled anesthetic isoflurane2, females are more resistant to the anesthetic than males, and that the difference results from testosterone modulation in males.

1. CAS Reg. No. 58-22-0.
2. CAS Reg. No. 26675-46-7.

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