What are the signs of low testosterone in males?

Testosterone is that all-important male sex hormone. It is necessary for sex formation, pubertal effects (e.g., body hair and deepening of the voice), sperm development, muscle growth, and the regulation of platelet aggregation (1). So, what happens when a male doesn’t have enough testosterone? Read on to find out about the common signs of low testosterone and what can be done to increase testosterone levels.

Note: Testosterone (at low levels) is also important in females, but this article is focused on male testosterone levels only.

What is defined as low testosterone?
The American Urology Association (LINK) defines low blood testosterone in men as less than 300 ng/dL (~10 nmol/L).

Signs of low testosterone in males
Low testosterone has differing effects depending on the age of the individual. Testosterone deficiency during fetal development can cause the incomplete development of male characteristics, while deficiency at puberty can slow growth and reduce the development of pubic hair, deeper voice, and penis and testes growth (2,3).

Low testosterone in adult males can cause a range of symptoms (2), including:

  • Reduced sex drive
  • Infertility
  • Fatigue
  • Reduced lean muscle mass
  • Increased body fat
  • Irritability
  • Erectile dysfunction
  • Depression
  • Loss of body hair
  • Sleeping issues
  • Osteoporosis

It is also important to note that these symptoms can be caused by other factors unrelated to testosterone levels, such as opioid use, diabetes, and obesity.

What are the possible causes of low testosterone?
Low testosterone can occur due to conditions that males are born with, such as Klinefelter syndrome, or testosterone may also decline for other reasons, including testicle injury, chemotherapy, infection (e.g., HIV), autoimmune disease, malnutrition, and hormonal imbalances. Metabolic syndrome (which encompasses high blood sugar, unhealthy cholesterol levels, and belly fat), obesity, and using certain medications can also lead to low testosterone production (2).

How is low testosterone diagnosed?
A simple blood test can be taken to measure testosterone levels, such as the test offered here. Additional tests may also be required to determine the cause of the low testosterone, including a luteinizing hormone (LH) blood test and MRI to determine if low testosterone is due to a pituitary problem, as well as an HbA1c test to screen for elevated blood sugar caused by diabetes (2).

What are ways to increase low testosterone?
Often simple lifestyle changes may be all that are required to increase testosterone levels, such as increasing physical activity and improving diet to lose weight for overweight males. In other instances, testosterone therapy may be required. However, testosterone therapy also comes with some potential risks, including an increased risk of blood thickening and interruption of normal sperm production (2).

1. Understanding how testosterone affects men. NIH Research Matters. Sept 2013.
2. What is Low Testosterone? Urology Care Foundation.
3. You and your Hormones, an education resource from the Society of Endocrinology. Reviewed May 2021.