Androgens in Health and Disease.pdf - E Library

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period after the burn. In these men, the serum LH and FSH responses to exogenous
GnRH are normal (129). Autopsy studies of men who have died of burns but did not have
scrotal injury reveal disordered spermatogenesis.
The illness may result from physical injury or systemic medical illness. In some
circumstances, the defects in testicular function are a result of treatment (e.g., head
irradiation for CNS tumors). In most of these situations, the hypogonadism is reversible
with resolution of the illness (130,131).
Although obesity is not considered an acute illness, free- and total testosterone levels
are decreased in men with a body mass index of 30 or greater. This is accompanied by
an attenuated LH pulse amplitude, suggesting that these men may be truly hypogonadal
because of their weight (132).
No studies have shown benefit from testosterone treatment of critically ill men.
Although it may be tempting to try androgen therapy to reverse their catabolic state, until
controlled studies demonstrate benefit, even short-term therapy should not be attempted
because it may be harmful (as was the case for thyroid-hormone-replacement therapy in
the critically ill).
Uremia
Hypogonadism is a common finding in men undergoing dialysis (133–135). Uremia
often is associated with marked hyperprolactinemia, and originally this was
thought to be the reason for the hypogonadism. However, if the prolactin level is
decreased with bromocriptine, the serum testosterone level remains low, although
the libido is improved. Two other factors in uremia may contribute to the hypogonadism.
One is zinc deficiency, although zinc replacement has not corrected the
hypogonadism completely (136). Androgen replacement in patients with uremia
who are receiving dialysis has been a standard practice, primarily as a means of
increasing erythrocyte production.
Hemochromatosis
In hemochromatosis, there are excessive tissue iron stores . Usually, hemochromatosis
is clinically manifest by the presence of liver disease, and the hypogonadism that
occurs in as many as 60% of these men originally was thought to be secondary to the
hepatic abnormalities. More recent investigations have shown that the causative lesion
resides in the pituitary and is related to the severity of iron overload (137). Serum
testosterone, LH, and FSH levels are low. The response of serum gonadotropins to
GnRH stimulation decreases as the severity of the systemic disease increases and is
totally absent in severe cases of hemochromatosis. However, the testes respond normally
to LH. Thus, the primary defect appears to be pituitary failure.
Treatment of the hemochromatosis with phlebotomy in young men results in a partial
normalization of hypothalamic–pituitary–gonadal function. However, this improvement
occurs in a minority of men and is only partial. The younger the man, the greater is the
likelihood of improvement; amelioration of established disease in men older than 40 yr
is rare (138).
COMBINED PRIMARY AND SECONDARY HYPOGONADISM
Aging
Women undergo a marked change in gonadal function with age, as evidenced by
menopause, but the situation in men is less clear. Early studies demonstrated a well-