Libido and Sexual Function
The most robust evidence for TRT relates to sexual health.
A comprehensive systematic review and meta-analysis published in The Journal of Clinical Endocrinology & Metabolism evaluated randomised placebo-controlled trials of testosterone therapy in men with confirmed hypogonadism. The analysis demonstrated statistically significant improvements in sexual desire, erectile function and overall sexual satisfaction compared with placebo.
Similarly, the coordinated Testosterone Trials, published in JAMA, showed that testosterone gel therapy in older men with low testosterone resulted in meaningful improvements in sexual activity, desire and erectile function scores.
These findings are clinically important. Sexual dysfunction in androgen-deficient men is not solely vascular or psychological. Testosterone plays a regulatory role in nitric oxide pathways, libido signalling and central nervous system sexual response. Restoration of physiological testosterone levels can therefore improve both desire and sexual performance when deficiency is present.
Australian clinical commentary published through Healthy Male reinforces that improvements are most consistent in men with clearly low baseline testosterone rather than those with borderline levels.
Energy and Correction of Anaemia
Fatigue is a common presenting complaint. While non-specific, low testosterone can contribute through several biological mechanisms including reduced erythropoiesis, impaired mitochondrial activity and altered muscle metabolism.
A significant study published in JAMA Network Open demonstrated that testosterone therapy corrected unexplained anaemia in a substantial proportion of hypogonadal men compared with placebo. Testosterone stimulates erythropoietin production and red blood cell formation, improving oxygen-carrying capacity. In men with low haemoglobin, correction of anaemia may translate into improved physical stamina and reduced exertional fatigue.
The Testosterone Trials also reported modest improvements in vitality scores, though these effects were less pronounced than improvements in sexual function. This highlights an important clinical point: TRT may improve energy in men whose fatigue is hormonally mediated, but it is not a universal treatment for tiredness caused by sleep deprivation, depression or chronic stress.
Australian expert commentary notes that energy improvements are typically gradual and correlate with restoration of testosterone into the mid-normal physiological range rather than supraphysiological dosing.
Mood and Cognitive Symptoms
Mood disturbance and reduced motivation are frequently attributed to testosterone decline, yet evidence in this domain is more nuanced.
Earlier studies produced mixed results; however, more recent analyses suggest benefit in specific subgroups. Secondary analyses from the Testosterone Trials, reported in journals including JAMA Psychiatry, showed modest improvements in depressive symptoms in men with low baseline testosterone and clinically relevant mood disturbance.
Testosterone receptors are present in brain regions involved in mood regulation, including the limbic system. Restoration of physiological androgen levels may improve motivation, reduce irritability and enhance sense of wellbeing in androgen-deficient men.
Australian clinical blogs and educational articles published through Healthy Male emphasise that TRT should not be viewed as a primary antidepressant therapy. However, in men with confirmed hypogonadism and concurrent low mood, testosterone optimisation may form part of a broader management strategy.
Importance of Appropriate Diagnosis
The clinical importance of TRT lies in appropriate patient selection. Treatment is indicated only when:
• Symptoms are consistent with androgen deficiency
• Morning testosterone levels are repeatedly below reference range
• Alternative causes of symptoms have been considered
The Endocrine Society guideline, published in The Journal of Clinical Endocrinology & Metabolism, stresses that therapy should aim to restore testosterone to physiological levels, not to enhance performance beyond normal.
This distinction is critical in primary care. Men with borderline laboratory values and non-specific symptoms may not derive the same benefit observed in clinical trials of clearly hypogonadal populations.
Safety Considerations
Erythrocytosis
The same meta-analysis in The Journal of Clinical Endocrinology & Metabolism identified erythrocytosis as the most consistent adverse effect. Elevated haematocrit increases blood viscosity and may elevate thrombotic risk if not monitored. Regular full blood count testing is therefore mandatory during treatment.
Prostate Health
TRT is contraindicated in men with untreated prostate or breast cancer. Baseline prostate-specific antigen testing and clinical assessment are standard practice prior to initiation.
Cardiovascular Risk
Cardiovascular safety has been the subject of significant debate. The recent TRAVERSE trial, published in The New England Journal of Medicine, evaluated men with hypogonadism and cardiovascular risk factors. Testosterone therapy was not associated with a higher incidence of major adverse cardiovascular events compared with placebo over the study period.
While reassuring, expert commentary in Nature Reviews Urology notes that longer-term data are still required, particularly in older men with established cardiovascular disease. Shared decision-making and monitoring remain essential.
Fertility Suppression
Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal axis, reducing endogenous testosterone production and spermatogenesis. This may significantly lower sperm count. Men planning future fertility should seek specialist advice prior to commencing therapy, as alternative treatments may be more appropriate.
Clinical Summary
In men with confirmed hypogonadism, TRT demonstrates the strongest evidence for improving libido and sexual function. Correction of anaemia and modest improvements in vitality and mood have also been demonstrated in well-designed randomised trials.
For Australian men presenting with fatigue, reduced motivation and declining sexual interest, careful evaluation is critical. When genuine androgen deficiency is identified, testosterone replacement can play an important therapeutic role. When deficiency is not present, alternative causes must be investigated.
The clinical value of TRT lies not in hormone enhancement, but in restoring physiological balance under appropriate medical supervision.
