Low testosterone or just getting older? How to tell the difference

Obesity rates have increased in recent years, with data showing that 73% of people with low testosterone have a BMI above the healthy range. One reason for this is that fat tissue contains an enzyme called aromatase, which converts testosterone into oestrogen. More fat means more testosterone is converted into oestrogen, leading to an imbalance in hormones.

Additionally, obesity often leads to insulin resistance and high insulin levels. Elevated insulin suppresses the production of SHBG (sex hormone-binding globulin) protein, which is responsible for carrying testosterone in the bloodstream. Low levels of SHBG result in low total circulating testosterone. This is why people with unmanaged diabetes often have low testosterone levels.

Stress can lower testosterone levels in several ways. Factors contributing to stress include not exercising or sleeping enough. One mechanism involves suppressing the hypothalamus and pituitary gland, two brain regions that produce hormones signaling the testes to make testosterone. So high stress levels lead to decreased signaling of GnRH (gonadotropin-releasing hormone) and LH (luteinising hormone), resulting in low testosterone levels.

Chronic stress also increases cortisol levels, which interferes directly with testosterone production by inhibiting the enzyme responsible for its production in the testes. While stress-related low testosterone levels can be reversible, it may take time to restore normal levels.

Testosterone production depends on sleep. You generally need at least three hours of quality, uninterrupted sleep for your body to make it properly.

Sleep disturbances and chronic insomnia can significantly lower testosterone levels. For instance, in one study, healthy men who reduced their sleep from around eight hours to only four hours for one week experienced a decrease in daytime testosterone levels by 10% to 15%. This shows that even a week of poor sleep can lead to significantly low testosterone levels.

Sleeping late can also disrupt your circadian rhythm, which can lead to hormone imbalances. Recovery from sleep deprivation often requires more than just a nap or one night of good sleep; it may take longer to restore balance.

Certain medications can interfere with testosterone production, leading to decreased levels. Antidepressants, such as SSRIs (selective serotonin reuptake inhibitors), have been found to drastically reduce testosterone levels. Studies show that different SSRIs affect testosterone levels in various ways, including interference with the CYP17 pathway, which is essential for testosterone synthesis, or increasing the effect on aromatase, converting testosterone to oestrogen.

Other medications include corticosteroids, which can lower testosterone levels, especially with long-term or high-dose systemic use. One study found that 12 patients using prednisone for respiratory conditions had 33% lower testosterone levels than placebo. But those using beclomethasone didn’t show significant decreases in testosterone levels. This shows that different corticosteroids can produce different effects. For example, prednisone can directly interfere with testosterone production in the testes, which leads to low testosterone levels.

Additionally, long-term use of ibuprofen, especially at high doses, can suppress testicular steroidogenesis, the process required to produce testosterone.

Physical injury or trauma to the testes can damage the Leydig cells, which are responsible for producing most of the body's testosterone. The effects of the damage can be temporary or permanent, depending on the severity of the injury.

If the injury causes mild swelling or temporary disruption of blood flow, testosterone levels can return to normal within a few weeks or months. But if permanent damage occurs, such as severe scarring or tissue death, testosterone levels may not return to normal without medical intervention.

Several environmental toxins have been associated with male hypogonadism. For example, tobacco smoke contains carcinogens that may impair sperm function. Men exposed to pesticides have also been linked to hypogonadism.

Approximately 85% of heroin addicts experience sexual dysfunction, while chronic opioid users often suffer from secondary hypogonadism.

Opioids disrupt the communication network between the brain and the reproductive system, which can impact testosterone levels, resulting in a condition called OPIAD (opioid-induced androgen deficiency). This happens when opioids bind to the site where hormones are made, suppressing their production, including GnRH. Without GnRH, lower levels of LH and FSH, decreasing testosterone levels.