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A "feedback loop" closely regulates the amount of hormone in the blood. The pituitary gland then relays signals to the testes to produce testosterone. Signals sent from the brain to the pituitary gland at the base of the brain control the production of testosterone in men. It is essential to the development of male growth and masculine characteristics. Learn all about the sex hormone here, including its primary benefits. There's more to testosterone than guys behaving badly. When you think of testosterone, what comes to mind?
But recent studies suggest it’s not just about symptoms. That’s called testosterone deficiency (sometimes called hypogonadism).2 This is normal, but in some men, the drop becomes steep enough to trigger symptoms like low libido, fatigue, muscle loss, and irritability. Only a small amount (around 1–2%) circulates as "free testosterone," which is the form that’s active and available to your body’s tissues, including the heart and blood vessels.2 In the bloodstream, most testosterone is bound to a protein called SHBG (sex hormone-binding globulin).
Are we failing to treat a large population of men who would benefit from hormone replacement therapy? Moreover, there are no data suggesting that testosterone supplementation into the normal physiological range leads to an increased risk of developing prostate cancer. In elderly and middle aged men with coronary disease, about one-quarter will have testosterone deficiency and symptomatic hypogonadism.42 In men with coronary disease, it remains unclear what role testosterone deficiency might play in the aetiology and progression of atherosclerosis or whether hypotestosteronaemia simply reflects chronic illness and frailty. If the Basaria trial had been done in hypothyroid patients with high cardiovascular risk and replacement had aimed at supra-physiological levels, the same (or worse) results would have been seen. The literature showed that testosterone replacement should be managed in the same way as thyroid hormone replacement. Hopefully, the current article has dealt with the former concern and has brought reassurance regarding physiological levels of testosterone and the male heart.
One reason lab conversations around TRT become confusing is that testosterone values are not independent of timing. This means women's TRT targets should not be "as high as possible while feeling good." The better standard is "the lowest effective exposure that stays within the female physiologic range and supports the specific symptom target under monitoring." It is to stay within the physiologic range for women while assessing whether the symptom that justified therapy is actually improving. Testosterone therapy in women has a much narrower evidence-based indication, with the strongest support in postmenopausal women with hypoactive sexual desire disorder (Davis et al., Journal of Sexual Medicine, 2019; Parish et al., Climacteric, 2021). The question of women's TRT target levels is even more delicate. In younger men, some authors have argued that a one-size-fits-all cutoff may miss clinically relevant low values when symptoms are present.
However, the wisdom and effectiveness of testosterone treatment to improve sexual function or cognitive function among postmenopausal women is unclear. As a result, there is some controversy about which men should be treated with supplemental testosterone. Testosterone may stimulate the prostate gland and prostate cancer to grow. The most common example is probably prostate cancer. There are times when low testosterone is not such a bad thing. For example, problem with function of pituitary gland or adrenal glands may lead to reduced testosterone production.
Your provider will always reference your laboratory’s normal ranges when interpreting your results. LH then travels to your gonads and stimulates the production and release of testosterone. Your hypothalamus releases gonadotropin-releasing hormone (GnRH), which triggers your pituitary gland to release luteinizing hormone (LH).

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