Causes of male hypogonadism include:

• Certain medicines, including glucocorticoids, ketoconazole, chemotherapy, and opioid pain medicines
• Diseases that affect the testicle, including hemochromatosis, mumps, orchitis, testicular cancer, testicular torsion, and varicocele
• Injury or trauma to the testicles
• Obesity
• Genetic diseases, such as Klinefelter syndrome or Prader-Willi syndrome
• Other diseases, such as cystic fibrosis

The following can increase the risk of male hypogonadism:

• Activities that cause constant, low-level injury to the scrotum, such as riding a motorcycle or bicycle
• Frequent or heavy use of marijuana
• Undescended testicles at birth

Symptoms depend on the age when male hypogonadism develops, either before or after puberty.

Symptoms may include:

• Enlarged breasts (gynecomastia)
• Infertility
• Less height increase than expected
• Loss of muscle mass
• Lack of sex drive (libido)
• Loss of armpit and pubic hair
• Slow development or lack of secondary male sex characteristics (hair growth, scrotum enlargement, penis enlargement, voice changes)

Men may also notice they do not need to shave as often.

A physical exam may show:

• Genitals that do not clearly look either male or female (usually found during infancy)
• Abnormally small, firm testicles
• Tumor or an abnormal mass in the testicle or the scrotum

Other tests may show low bone mineral density and fractures. Blood tests may show a low level of testosterone and high levels of prolactin, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). These hormone levels determine if the hypogonadism is primary or secondary (due to a pituitary gland problem).

If your concern is fertility, your health care provider may also order a semen analysis to examine the number of healthy sperm you are producing.

Sometimes, an ultrasound of the testes will be ordered.

Hypogonadism may be hard to diagnose in older men because testosterone level normally decreases slowly with age.

Hypogonadism also may be hard to diagnose in obese men. This is because obesity lowers a carrier molecule for testosterone called sex hormone binding globulin (SHBG). The free testosterone level in the blood is usually normal in obese men who do not have hypogonadism.

Male hormone supplements may treat some forms of hypogonadism. This treatment is called testosterone replacement therapy (TRT). TRT can be given as a gel, patch, injection, or implant.

Avoiding the medicine or activity that is causing the problem may bring testicle function back to normal.

Many forms of male hypogonadism cannot be reversed. TRT can help reverse symptoms, although it may not restore fertility.

Men who are having chemotherapy that can cause hypogonadism should discuss freezing sperm samples before starting treatment.

Male hypogonadism that begins before puberty will stop normal body growth. It can prevent adult male characteristics (such as deep voice and beard) from developing. This can be treated with TRT.

Men who take TRT need to be carefully monitored by their provider. TRT may cause the following:

• Enlarged prostate, leading to difficulty urinating
• Blood clots
• Changes in sleep and mood
• Changes in good cholesterol (HDL)
• Blood becomes too thick (polycythemia)

Contact your provider if you have symptoms of hypogonadism.

Also, contact your provider if you're on TRT and you think you're having side effects from the treatment.

Avoid higher-risk activities if possible.

Remain active and prevent weight gain as you get older.

Primary hypogonadism - male; Testicular hypofunction

Matsumoto AM, Anawalt BD. Testicular disorders. In: Melmed S, Auchus RJ, Goldfine AB, Rosen CJ, Kopp PA, eds. Williams Textbook of Endocrinology. 15th ed. Philadelphia, PA: Elsevier; 2025:chap 17.

Schlegel PN. Clinical management of male infertility. In: Robertson RP, ed. DeGroot's Endocrinology. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 113.

Swerdloff RS, Wang C. The testis and male hypogonadism, infertility, and sexual dysfunction. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 216.

US Food and Drug Administration website. FDA drug safety communication: FDA cautions about using testosterone products for low testosterone due to aging; requires labeling change to inform of possible increased risk of heart attack and stroke with use. www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-fda-cautions-about-using-testosterone-products-low-testosterone-due. Updated February 28, 2025. Accessed May 8, 2025.

Updated by: Sandeep K. Dhaliwal, MD, board-certified in Diabetes, Endocrinology, and Metabolism, Springfield, VA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.