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It's all about testosterone

Mens health new 1280.jpg

It's all about testosterone

The endocrine system plays an important role in men’s health, as Victoria Goldman explains…

Testosterone, produced by the testes, is the most important sex hormone in men. Deficiency can affect men’s fertility and sexual performance.1 High levels of cortisol, produced by the adrenal gland, especially at times of stress, can inhibit testosterone production.2,3
Melatonin, produced by the pineal gland, also helps to control testosterone synthesis, and very large doses can have negative effects on a man’s reproductive system.4,5 The adrenal glands produce smaller amounts of some male sex hormones, including testosterone and dehydroepiandrosterone (DHEA).6

The role of testosterone
Testosterone triggers the development of male reproductive organs in the foetus, and male characteristics at puberty, as well as sperm production.1 It plays various other roles in a man’s body, including stimulating libido and aggression, triggering hair growth and collagen and sebum production, affecting heart output and blood flow, and improving muscle growth and bone strength.7

Testosterone production is controlled by a feedback system between the testes, hypothalamus and pituitary gland.8The hypothalamus secretes gonadotropin-releasing hormone, which stimulates the pituitary gland to produce follicle-stimulating hormone (FSH) and luteinising hormone (LH).9 These hormones, in turn, trigger the testes to produce testosterone.9 The increase in testosterone then stops gonadotropin-releasing hormone, FSH and LH secretion by the hypothalamus and pituitary gland, creating the feedback loop.9

Testosterone deficiency (hypogonadism) occurs when a man’s body is unable to make enough testosterone.10Primary deficiency is usually the result of a problem with the testes. There are a number of potential causes - undescended testicles at birth, a genetic condition, trauma, a mumps infection or cancer treatment.10

Secondary deficiency may be a problem with brain or pituitary glands that affects the feedback system, including pituitary tumours, chronic medical conditions, HIV/AIDs and some medicines.10

According to British Society for Sexual Medicine (BSSM) Guidelines on Adult Testosterone Deficiency, with Statements for UK Practice, published in 2017,7 testosterone deficiency is more common in older men and men with obesity, chronic health conditions (such as type 2 diabetes, high blood pressure and heart disease), and poor overall health.

Medicines that can affect testosterone levels include oral glucocorticoids, regular opioid use, antipsychotic medicines, chemotherapy plus radiation, and anticonvulsants.7

Testosterone deficiency in men often causes sexual problems – low libido, decreased or absent morning and night-time erections, and erectile dysfunction.7 However, it may also cause more general symptoms as well.7

Dr Luke Pratsides, lead GP for Numan and NHS GP in east London, says increasing evidence shows that testosterone levels in men decrease at a rate of around 1 per cent a year from the age of 40 onwards. “Most men have enough reserve testosterone so that they don’t see any impact day-to-day,” he says.

“However, for some men this gradual reduction crosses a symptomatic threshold, and they experience symptoms such as diminished sex drive, erectile dysfunction, subfertility, low stamina, muscle atrophy, decreased energy and lower mood. A large European study demonstrated a prevalence of 3.2 per cent in men aged 60-69 years, 5.1 per cent in men aged 70-79 years.”

Diagnosis and management
Many men with testosterone deficiency remain undiagnosed.19 According to the BSSM guidelines, all men with erectile dysfunction, loss of spontaneous erections, or low sexual desire should have their testosterone levels checked.7 This also applies to men with type 2 diabetes, a BMI over 30 kg/m2 or a waist circumference of over 102 cm, and those taking long-term opiates, antipsychotics or anticonvulsants.7

Testosterone deficiency is treated with hormone replacement therapy, usually in the form of a gel that is applied to the skin.10 “A man should only take prescribed testosterone hormone replacement therapy when they have a confirmed testosterone deficiency on a blood test,” says Dr Pratsides.

“They should be aware of the risks of testosterone therapy which include acne, reduced sperm production, increased risk of blood clotting, breast enlargement, enlargement of the prostate and growth of pre-existing prostate cancer. They should have access to clinical advice and a review throughout to ensure the testosterone replacement therapy remains safe for them.”

Some men take DHEA in the form of illegal anabolic steroids to increase their testosterone levels and boost muscle mass and strength, but these products can have serious side effects.1 “In particular, these can cause an overproduction of red blood cells leading to higher risk of clot formation,” says Dr Pratsides. “Anabolic steroids can cause the testicles to shrink and cause reduced fertility which is particularly important for younger men who have plans of starting a family in the future.”

Erectile problems
Erectile dysfunction is particularly common in men over 40 and can be a sign of testosterone deficiency.11However, it may be linked to the use of certain medicines (eg. beta-blockers or antidepressants) and recreational drugs, including alcohol.11 It may also be related to lifestyle factors or underlying health conditions, such as obesity, stress, smoking, high cholesterol, diabetes, nerve damage or metabolic syndrome.11

“Wherever possible, it’s important to make a man aware that erectile dysfunction is often a sign of an underlying health issue,” says Dr Pratsides. “This can be due to cardiovascular disease from high cholesterol or diabetes, as well as a mental health issue such as performance anxiety or low mood. If an underlying cause is suspected, pharmacy teams can signpost customers to the best service to have the issue investigated and treated.”

Erectile dysfunction can usually be managed with a combination of medicines, lifestyle changes and counselling.11 An oral phosphodiesterase type-5 inhibitor, such as sildenafil, is the first-line medicine for erectile dysfunction.12 This works by increasing the blood flow to the penis.12 If medicines aren’t suitable or don’t work, some men try vacuum pumps.11

“Viagra Connect, containing sildenafil, is available over the counter from pharmacies and often provides a ‘quick fix’ solution to erectile problems,” says Dr Pratsides. “However, it’s important to screen for conditions that may mean treatment is contraindicated, such as a recent heart attack or stroke and certain eye diseases.”


1. Your and your hormones: Testes. Society for Endocrinology., last reviewed Feb 2018
2. Your and your hormones: Cortisol. Society for Endocrinology., last reviewed January 2018
3. Davey Smith G et al. Cortisol, Testosterone, and Coronary Heart Disease. Circulation. 2005;112:332–340
4. Your and your hormones: Melatonin. Society for Endocrinology., last reviewed March 2018
5. Li C, Zhou X. Melatonin and male reproduction. Clin Chim Acta. 2015 Jun 15;446:175-80. doi: 10.1016/j.cca.2015.04.029. Epub 2015 Apr 25. PMID: 25916694.
6. Your and your hormones: Dehydroepiandrosterone. Society for Endocrinology., last reviewed January 2022
7. Hackett G, Kirby M, Edwards D, Jones TH, Wylie K, Ossei-Gerning N, David J, Muneer A. British Society for Sexual Medicine Guidelines on Adult Testosterone Deficiency, With Statements for UK Practice. J Sex Med. 2017 Dec;14(12):1504-1523. doi: 10.1016/j.jsxm.2017.10.067. PMID: 29198507.
8. Hypogonadism: pathophysiology. Medscape., updated December 2021
9. Your and your hormones: Testosterone. Society for Endocrinology., last reviewed May 2021
10. Testosterone deficiency. Patient., last reviewed July 2018
11. Erectile dysfunction. Patient., last reviwed May 2019
12. Erectile dysfunction. NICE British National Formulary.

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