Definition and Overview

Testosterone replacement therapy, also known as androgen replacement therapy, is often prescribed to patients suffering from the effects of male hypogonadism, a condition characterised by the diminished functional activity of the gonads or testes.

Testosterone is a type of steroid hormone primarily secreted by the testicles and adrenal glands. It is important in the development of male reproductive tissues and promotes secondary sexual characteristics including increased bone and muscle mass, as well as growth of body hair. Other than its physical contributions to the male (and in small amounts, female) body, it is also essential to an individual’s health and well-being. Research shows that testosterone plays a key role in fueling a man’s mental and physical energy, and in regulating the fight-or-flight response and other key evolutionary features exclusive to humans. It also helps prevent the onset of osteoporosis.

The production of the testosterone hormone slows down due to the natural process of aging. Andropause, the male version of menopause, is speculated to be the result of this process. Individuals going through this condition can experience a variety of symptoms, including depression, increased body fat levels, reduced muscle mass, difficulty in concentrating or sleeping, decreased motivation to perform productive or pleasurable tasks, physical weakness, decreased bone density, gynaecomastia (or the appearance of breasts in male patients), reduced libido, and erectile dysfunction.

Research shows that a majority of men experience a fifty percent drop in testosterone levels when they reach age 80. Some patients, however, experience the same thing much earlier, which can seriously affect their daily lives. In these patients, the early onset of andropause symptoms can be addressed with testosterone replacement therapy.

Who Should Undergo and Expected Results

Aside from patients experiencing low testosterone levels at an early age, testosterone replacement therapy can also be recommended to alleviate some of the symptoms experienced by patients suffering from the following conditions:

  • Hypogonadism, especially in patients who are experiencing symptoms such as fatigue and anaemia
  • Osteoporosis
  • Diabetes mellitus
  • Erectile dysfunction
  • Dementia
  • Chronic heart failure

The therapy can also be recommended to transgender men, so their bodies can manifest the physical characteristics of the gender they identify with.

How is the Procedure Performed?

There are several forms in which testosterone replacement therapy is administered and most can be performed by the patient himself under the supervision of a qualified medical professional. These include the following:

  • Transdermal TRT. This involves the application of a skin patch containing the medication on the upper body or arms once a day for the duration of the treatment. The medication is then absorbed through the skin and enters the bloodstream to normalise the patient's testosterone levels.

  • Topical gels. This involves the application of clear gel infused with testosterone on the shoulders, upper arms, or abdomen. Testosterone gels are available only through prescription. Available brands in the market include AndroGel, Fortesta, and Axiron. There is also a brand that can be applied inside the patient’s nose called Natesto.

  • Injections or implants. With these options, a qualified medical professional injects the testosterone directly into the patient’s muscles or surgically place pellet-sized implants in the soft tissues. The implants are designed to provide a slow but constant infusion of testosterone into the body. The insertion is performed under local anaesthesia and one pellet typically lasts up to six months.

  • Pills. Oral testosterone pills are available in the market, but many doctors advise against them as they can damage the liver. Other forms of TRT bypasses the liver and gets testosterone directly into the blood.

  • Mouth patch. This involves placing a patch or tablet in the mouth two times a day. The patch releases the hormone into the bloodstream through the tissues in the mouth.

Possible Risks and Complications

Testosterone replacement therapy is linked to both mild and serious medical conditions. As such, patients are highly advised to discuss and weigh the therapy’s pros and cons with their physicians before the treatment starts. Risks and possible complications include:

  • Development of benign prostatic hypertrophy, a condition that involves the enlargement of the prostate gland.
  • Worsening of sleep apnoea
  • Formation of blood clots in the veins, which can increase the risk of deep vein thrombosis and pulmonary embolism
  • Increased risk of prostate cancer
  • Worsening of congestive heart failure


  • Bhasin S, et al. Testosterone therapy in men with androgen deficiency syndromes: An Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism. 2010;95:2536.

  • Longo DL, et al. Disorders of the testes and male reproductive system In: Harrison's Principles of Internal Medicine. 18th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. Accessed Feb. 4, 2015.

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