What is testosterone?
Testosterone is a steroid hormone derived from cholesterol. It is the major sex hormone in males. It is responsible for the development of the male reproductive organs, sperm production, sex drive, deepening of the voice, and the development of facial and pubic hair growth starting at puberty. It is also responsible for muscle and bone growth and may also help maintain mood and cognitive function.
Testosterone levels spike during adolescence and peak when men are in their 20s. From here, total testosterone levels gradually fall at an average of 1.6% per year. Although most older men have normal testosterone levels, the proportion of men with testosterone deficiency increases with age; 20% of men aged over 60 have low testosterone and up to 50% of those over 80 years of age. If testosterone levels drop too low, men may experience a number of symptoms such as low libido, erectile difficulties, loss of muscle mass, low mood and fatigue.
Testosterone deficiency can be caused by several conditions. It may present from birth or develop later in life.
Primary testosterone deficiency occurs when the testes don’t produce enough testosterone. This can be caused by direct injury to the testes, infection tumours, and some genetic conditions.
Parts of the brain (the hypothalamus and pituitary gland) secrete hormones (LH, FSH) that stimulate the testes to produce testosterone. In secondary testosterone deficiency, the testes are functioning normally, however, there is a problem with the hypothalamus or pituitary gland which results in low testosterone levels. This can be caused by tumours of the pituitary gland, certain infections, and also medications including opiates and anabolic steroids.
Aside from these conditions, a person’s lifestyle can have a big impact on testosterone levels. Studies have shown that not getting enough sleep is linked with lower testosterone levels.
Obesity and type 2 diabetes are metabolic disorders largely driven by lifestyle - both are closely linked with testosterone deficiency. Men who are obese or overweight are much more likely to have testosterone deficiency than those of a healthy weight. Thriva user data tells us that the incidence of low testosterone increases with age, and that it is more common in people with BMI levels above 25.
Similarly, testosterone deficiency is more common in individuals with type 2 diabetes. One cross-sectional study showed that 47% of men with type 2 diabetes had a reduced total testosterone level. Thriva user data also shows this. 18.3% of Thriva users with raised HbA1c found in diabetes had low levels of testosterone, compared to only 8.4% of those with normal HbA1c levels.
These effects are reversible. Studies have shown in obese men with low testosterone, losing weight (through diet or bariatric surgery) results in an increase in testosterone levels.
The links between obesity, diabetes and testosterone deficiency are bidirectional. Not only do obesity and diabetes impact your risk of having testosterone deficiency, low levels of testosterone can increase the risk of becoming obese, or developing diabetes in the future. Replacing testosterone in individuals with type 2 diabetes and low levels of testosterone can lead to better glycaemic control and even remission of the disease. Some evidence suggests that it can also lead to weight reduction in obese men and improvement in other metabolic markers such as triglyceride levels.
Thriva Solutions have an array of men’s health diagnostic solutions to support health businesses and employers looking to increase their health benefits for employees. This November, we’re also excited to announce a new partnership with LloydsPharmacy Online Doctor, a trusted, science and evidence-based organisation, to bring diagnostic testing to their business. Partnering with Thriva Solutions will enable Lloyds’ patients to receive testosterone, alongside metabolic markers (HbA1c, lipids, liver blood tests) as part of their men’s health package.