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Key Clinical Updates in Male Hypogonadism

An oral preparation of testosterone undeconoate (Jatenzo) is available in capsules of 158 mg, 198 mg, and 237 mg and should be taken with food.

Serum testosterone falls to low levels by 12 hours after an oral dose; dosing every 8 hours may produce more consistent serum testosterone levels.

Testosterone replacement has not been considered to significantly increase the risk of thromboembolic events in most hypogonadal men.

However, one large medical database study has found a correlation between testosterone therapy and thromboembolic events, particularly in men with a prior history of vascular events and in men being prescribed testosterone without proper documentation of hypogonadism.


  • Diminished libido and erections.

  • Fatigue, depression, reduced exercise endurance.

  • Testes small or normal in size.

  • Low serum total testosterone or free testosterone.

  • Hypogonadotropic hypogonadism: low or normal serum LH and FSH.

  • Hypergonadotropic hypogonadism: testicular failure, high serum LH and FSH.


Male hypogonadism is caused by deficient testosterone secretion by the testes. It may be classified according to whether it is due to (1) insufficient gonadotropin secretion by the pituitary (hypogonadotropic); (2) pathology in the testes themselves (hypergonadotropic); or (3) both (Table 26–13). Partial male hypogonadism may be difficult to distinguish from the physiologic reduction in serum testosterone seen in normal aging, obesity, and illness.

Table 26–13.Causes of male hypogonadism.


A. Hypogonadotropic Hypogonadism (Low Testosterone With Normal or Low LH)

A deficiency in FSH and LH may be isolated or associated with other pituitary hormonal abnormalities. (See Hypopituitarism.) Hypogonadotropic hypogonadism can be primary, defined as failure to enter puberty by age 14, or it can be acquired. Causes of primary hypogonadotropic hypogonadism include isolated hypogonadotropic hypogonadism, hypopituitarism, or simple constitutional delay of growth and puberty. Causes of apparently acquired etiologies include genetic conditions (eg, Kallmann syndrome or PROKR2 mutations, X-linked congenital adrenal hypoplasia, 17-ketosteroid reductase deficiency, Prader-Willis syndrome), which account for about 40% of cases of isolated, and apparently idiopathic, acquired hypogonadotropic hypogonadism with a serum testosterone level less ...

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