Decreased Libido

Decreased sexual drive.

Libido appears to be testosterone-dependent in both women and men. In women, ovarian hormones and adrenal androgens begin to decrease in the years preceding menopause. A decrease or loss of libido along with a diminished sense of well-being, loss of energy, and loss of bone mass can result.

Causes of decreased libido include low bioavailable testosterone (ie, testosterone not bound to sex hormone-binding globulin), elevated prolactin, and, indirectly, decreased estrogen. Additionally, use of alcohol or drugs may affect sexuality in women. (see Table 114-1) The literature on the effect of drugs on libido in women is scant; however, anticonvulsants such as carbamazepine, phenytoin, primidone, and phenobarbital and anticancer drugs such as tamoxifen may decrease sex drive. Newer antidepressants (eg, selective serotonin reuptake inhibitors) may inhibit libido, arousal, and orgasm. Incontinence can also decrease libido and inhibit arousal.

In evaluating decreased libido in women, as in men, the physician should measure bioavailable testosterone levels rather than total testosterone levels. Sex hormone-binding globulin levels tend to increase with age, and total testosterone levels may not reflect what is actually active in the body. Bioavailable testosterone measures the nonsex hormone-binding globulin bound portion of testosterone.

Women with decreased libido may benefit from androgen therapy if baseline testosterone levels are low. Most data regarding testosterone use are from studies of women who have undergone oophorectomy; however, testosterone may increase sexual interest and frequency of fantasy even in women with natural menopause. Oral 17-alkylated testosterone (the only oral form of testosterone available in the USA) may be used in combination with estrogen. Adverse effects of oral 17-alkylated testosterone include hepatotoxicity, potential long-term increases in cardiovascular risk (even if the lipid profile remains normal), and virilization (eg, hirsutism, acne, lowered voice). Ideally, 17-alkylated testosterone is used. When giving low-dose intramuscular testosterone enanthate or cypionate (eg, 25 mg every 2 to 4 weeks), the physician should monitor clinical response as well as bioavailable testosterone levels and Hct. Subcutaneous use of testosterone pellets is rare in the USA; long-term use of testosterone has not been established. Duration of treatment depends on response and whether withdrawal of testosterone results in recurrence of problems. Currently, there are no long-term (> 5 years) prospective data on testosterone use in women.