testosterone

Testosterone is a sex-steroid hormone present in people of all sexes. Its effects depend partly on its balance with estrogen and on how much is free versus bound to transport proteins. 1

• Behavior and motivation: Testosterone can increase libido, novelty-seeking, and willingness to compete, and may lower anxiety. Its effects are contextual: it tends to amplify existing tendencies and behaviors rewarded with status, rather than simply causing aggression. 2 3
• In women: Testosterone is also present and is important to consider for health optimization; before menopause, ovarian theca cells can produce it. 4 5
• Estrogen matters too: Testosterone can convert to estrogen through aromatase. In men, estrogen that is too low can impair libido, so testosterone alone doesn’t tell the whole story. 6
• Testing and treatment: Levels and symptoms need clinical interpretation. The discussion emphasizes checking bloodwork and working with a physician when considering testosterone therapy, because dose-related risks and effects across multiple organ systems require monitoring. 7 8
• Free versus total testosterone: Much testosterone is bound to SHBG or albumin, which help transport it to tissues; a higher free level is not automatically better in every situation. 9