Low testosterone in men is called hypogonadism. Hypogonadism occurs due to inadequate production of testosterone and sperm by the male testis. It can be classified as congenital (present at birth) or acquired. The vast majority of cases are acquired.

Symptoms of hypogonadism are variable. Congenital hypogonadism causes incomplete sexual development at birth or abnormal pubertal development. Acquired hypogonadism can cause a variety of symptoms:

  • Fatigue
  • Low libido (sex drive)
  • Erectile dysfunction
  • Weight gain
  • Depression
  • Frequent urination
  • Muscle loss/weakness
  • Depression/mood changes
  • Irratibility
  • Infertility
  • Breast enlargement
  • Breast tenderness

Causes of hypogonadism are broadly classified into two groups: primary (testicular dysfunction) or secondary (dysfunction of the hypothalamus or pituitary). Most men have secondary hypogonadism. The list of conditions that result in secondary hypogonadism is very long. Some of the more common causes are listed below:

  • Sleep apnea
  • Chronic opiate/narcotic use
  • Pituitary tumors
  • Chronic illness
  • Prior use of anabolic steroids
  • Elevated prolactin
  • Head trauma
  • Diabetes
  • Steroid use (prednisone)

The diagnosis is established by measuring testosterone in the serum. Secondary hypogonadism will be associated with low or normal levels of LH and FSH, the pituitary hormones that regulate testosterone production. In such cases, a MRI scan of the pituitary is often needed to rule out structural pituitary diseases.

The treatment of hypogonadism usually involves treating any underlying condition that may be causing it. If testosterone therapy is required, it can be administered as topical gels, patches or by injections. In some cases drugs such as clomiphene citrate or human chorionic gonadotropin may be used, especially if the patient needs to maintain fertility.