Signs and symptoms of low testosterone can include:

• Reduced sexual desire.
• Infertility.
• A decrease in spontaneous erections (such as during sleep).
• Swollen or tender breasts (gynecomastia).
• Loss of body and pubic hair.
• Small or shrinking testes.
• Height loss and thinning bones.
• Reduced muscle bulk and strength.
• Hot flushes and sweats.

Other signs and symptoms can include:

• Decreased energy, motivation and self-confidence.
• Feeling sad or depressed.
• Poor concentration and memory.
• Sleep apnea or other sleep problems.
• A low red blood cell count (mild anemia).
• Increased body fat.
• Diminished physical or work performance.

Testosterone replacement therapy:

Treatment of low testosterone due to aging with testosterone replacement therapy. It increases the risk of prostate cancer.

Symptoms caused by testosterone deficiency are similar to symptoms caused by other things.

Signs and symptoms can include:

• A number of other health problems such as liver disease, kidney failure, or an overactive or underactive thyroid.
• Side effects of medications.
• Lifestyle choices such as excessive alcohol use or use of illegal drugs.
• Psychological conditions, such as depression or emotional distress related to life changes that come with middle age (the so-called midlife crisis).