WHAT CAUSES TESTOSTERONE DEFICIENCY (HYPOGONADISM)?

Hypogonadism may be present at birth (congenital) or may develop later (acquired).

Testosterone deficiency is classified by the location of its cause along the hypothalamic-pituitary-gonadal axis:

• Primary, disruption in the testicles
• Secondary, disruption in the pituitary
• Tertiary, disruption in the hypothalamus

The most common congenital cause is Klinefelter’s syndrome.  This condition, which is caused by an extra X chromosome, results in infertility, sparse facial and body hair, abnormal breast enlargement (gynecomastia), and small testes.

Congenital hormonal disorders such as leutenizing hormone-releasing hormone (LHRH) deficiency and gonadotropin-releasing hormone (GnRH) deficiency (e.g., Kallmann’s syndrome) also may cause testosterone deficiency.

Other congenital causes include absence of the testes (anorchism; also may be acquired) and failure of the testicles to descend into the scrotum (cryptorchidism).

Acquired causes of testosterone deficiency include the following:

• Chemotherapy
• Damage occurring during surgery involving the pituitary gland, hypothalamus, or testes
• Glandular malformation
• Head trauma that affects the hypothalamus
• Infection (e.g., meningitis, syphilis, mumps)
• Isolated LH deficiency (e.g., fertile eunuch syndrome)
• Radiation therapy
• Testicular trauma
• Tumors of the pituitary gland, hypothalamus, or testicles

Studies have also shown that men with obesity, diabetes, or hypertension may be twice as likely to have low testosterone levels.