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Great News For Male Testosterone Replacement

Testosterone deficiency negatively affects a man’s quality of life and is a known risk factor for early death. Testosterone levels are at their highest by early adulthood and then decrease by 1 to 2 percent a year beginning in the 40s. This is why I screen my male patients for testosterone deficiency (also known as testicular hypofunction or hypogonadism).

Deficient levels of testosterone have wide-ranging effects since this hormone acts on almost every tissue in the body. Testosterone has effects on the brain, skin, bones, and heart and impacts erectile function, fat metabolism, muscle growth, bone density, energy production, lipid levels, insulin balance, and much more.

Testosterone deficiency in men increases the risk of all-cause and cardiovascular mortality. For example, a study done on Californian men aged 51 to 91 found that those with low testosterone levels were 40 percent more likely to die than those with higher testosterone levels.

Variables that were taken into account included lipid levels, age, and other factors. The same study found low testosterone levels were associated with death from respiratory and cardiovascular disease.

Common signs and symptoms of testosterone deficiency include:

  • reduced energy
  • reduced endurance
  • diminished work and/or physical performance
  • fatigue
  • depression
  • reduced sex drive
  • changes in erectile function (ED)
  • impaired memory
  • irritability
  • insomnia
  • reduced muscle
  • bulk and strength
  • increased body fat

Additional possible signs and symptoms of testosterone deficiency include visual changes, anosmia (loss of smell), incomplete or delayed sexual development, loss of body (axillary and pubic) hair, very small testes, breast discomfort, gynecomastia (abnormal swelling of male breast tissue), inability to father children, low sperm count, height loss, low trauma fractures, low bone mineral density, hot flashes, and sweats.

New Safety Studies

In recent years, published research has shown that testosterone replacement is quite safe when it comes to increasing the risk of prostate and cardiovascular problems. The two most extensive studies have been recently published, demonstrating additional excellent safety for these health concerns.

The first study examined prostate safety during testosterone replacement in men with hypogonadism (testosterone deficiency). The results were that there was not any statistical significance compared to men in the placebo group regarding an increased incidence of prostate cancer, acute urinary retention, invasive surgical procedures, prostate biopsy, and International Prostate Symptom Score. In addition, PSA levels increased more in the testosterone group than in the placebo group. This correlated with what The American College of Physicians stated in 2020: “Evidence from 20 observational studies with a mean follow-up ranging from 0.73 to 10.3 years showed no increased risk for mortality, cardiovascular events, prostate cancer, or pulmonary embolism or deep venous thrombosis.”  

The second study examined the cardiovascular safety of testosterone-replacement therapy in middle-aged and older men between the ages of 45 to 80 years who had preexisting or a high risk of cardiovascular disease with hypogonadism (testosterone deficiency). Daily transdermal testosterone had less incidence of cardiovascular events compared to placebo.


The most extensive studies demonstrating the safety of testosterone replacement in men have been recently published. The excellent safety findings are a welcome sight for my male patients who require testosterone replacement. Of course, proper monitoring by a doctor is necessary for men on long-term replacement therapy.

Dr. Mark Stengler NMD, MS, is a bestselling author in private practice in Encinitas, California, at the Stengler Center for Integrative Medicine. His newsletter, Dr. Stengler’s Health Breakthroughs, is available at and his product line at


Portions of this article are adapted from my book Healing The Prostate (Hay House), available at

Bhasin, S., Travison, T. G., Pencina, K. M., O’Leary, M., Cunningham, G. R., Lincoff, A. M., Nissen, S. E., Lucia, M. S., Preston, M. A., Khera, M., Khan, N., Snabes, M. C., Li, X., Tangen, C. M., Buhr, K. A., & Thompson, I. M. (2023). Prostate safety events during testosterone replacement therapy in men with hypogonadism. JAMA Network Open, 6(12).

 Lincoff, A. M., Bhasin, S., & Mitchell, L. M. (2023). Cardiovascular safety of testosterone-replacement therapy. New England Journal of Medicine, 389(12), 1148–1151.

Qaseem, A., Horwitch, C. A., Vijan, S., Etxeandia-Ikobaltzeta, I., & Kansagara, D. (2020). Testosterone treatment in adult men with age-related low testosterone: A clinical guideline from the American College of Physicians. Annals of Internal Medicine, 172(2), 126–133.