Female Sexual Dysfunction
Regular Periods Do Not Rule Out Low Testosterone in Young Women
By eInternal Medicine News: Kate Johnson
Feb 16, 2003, 5:40pm

When a young woman complains of low libido, the problem could be low testosterone even if she has regular menstrual periods.

That point was made by several experts in female sexual dysfunction (FSD) at the 10th World Congress of the International Society for Sexual and Impotence Research.

“Faced with this complaint of low libido from a young female patient, most physicians don't even consider looking at hormones. In fact, if the woman is having regular periods, they consider this proof that her hormones are fine,” said Dr. Andre Guay, an endocrinologist and director of the Center for Sexual Function Endocrinology, Peabody, Mass.

Physicians may mistakenly assume that if a woman has regular periods, her testosterone production must be normal. But women get only half of their testosterone from their ovaries; the other half is from their adrenals. So even though ovarian function might be normal, decreased adrenal function could result in low levels of testosterone.

“You have to recognize the two different steroid pathways for female testosterone production. For years, we've known that 40% of women who take the birth control pill have low libido, which makes sense because what you're doing with the birth control pill is that you're shutting off the ovary, so you're losing half your testosterone production. On the other hand, in women who have asthma or lupus and who are taking steroids, you are shutting off the adrenals, which is the other half of their testosterone production. So there are a lot of clinical conditions, especially in premenopausal women, where you shut off one or the other or even both of these sources of testosterone,” Dr. Guay said in an interview.

In a study conducted by Dr. Guay of premenopausal women aged 20-49 years who had regular menstrual periods, 18 had a diagnosis of FSD, and another 18 had normal sexual function. At baseline, women with FSD had significantly decreased levels of testosterone and adrenal androgen precursors (dehydroepiandrosterone-sulfate or DHEA-S) but not ovarian androgen precursors (androstenedione), compared with women with normal sexual function.

When the women were given an ACTH stimulation challenge, women both with and without FSD responded to the test, indicating that the adrenal glands respond normally in women with FSD, but there may be a possible defect in the steroid synthesis chain, he said.

In another study presented at the meeting, Dr. Ricardo Munarriz retrospectively reviewed all patients with FSD and adrenal insufficiency who were treated with DHEA supplementation at his clinic, the Institute for Sexual Medicine at Boston University.

In a sample of 136 women, mean age 37 years, with an average of 13 years' duration of FSD symptoms, scores on the Sexual Distress Scale were significantly improved (from 35.7 to 19.6), as were scores on the Female Sexual Function Inventory (from 36 to 62), after a mean of 8 months treatment with DHEA therapy. Patients were monitored throughout the study to ensure that normal androgen levels were maintained. Only 10% of subjects reported mild side effects.

“We know from studies that an estimated 43% of women have some form of sexual dysfunction, and of these, 32% have hypoactive sexual desire. Out of these women, somewhere between 60% and 80% have androgen insufficiency—that's an estimated 30 million to 35 million in the United States alone,” Dr. Munarriz said. “Women with these complaints should at least be screened, and if there is a problem, they can be referred.”

Dr. Munarriz acknowledged that the issue of low testosterone levels in young women is highly controversial, and that screening tests for this are problematic because they are designed to measure male levels of the hormone. But total testosterone levels can still provide some useful information in women.

Any woman “who has levels below what is generally considered normal range is obviously abnormal, but we also consider that the normal range is not accurate,” he said. A consensus panel agreed last summer that even women in the lower third of normal should be considered abnormal. “In other words, they also have androgen insufficiency.”

Dr. Guay cautioned that physicians should be sure to measure DHEA-sulfate levels, as opposed to simply DHEA.

“If the total testosterone level is below 30 ng/dL, and DHEA-S levels are below 100 µg/dL, that's significant. That highlights a problem, especially in a younger woman. But even women in their 50s shouldn't have levels below this,” Dr. Guay said.

Dr. Munarriz recommended that DHEA replacement therapy should start at 50 mg/day, but because DHEA is readily available as a nutritional supplement and therefore is not regulated, physicians must be careful about monitoring their patients' blood levels to confirm its effect. “If androgen levels do not reach the normal range, either you don't have a good brand, or you need to increase the dose.”

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