In healthy women the primary hormones produced by the ovaries are estrogens and progesterone, but they also produce testosterone both before and after menopause. Although normal blood levels of testosterone in women are much lower than in men, testosterone is thought to have important physiologic effects in women, particularly on muscle function, body composition, sexual function and cognitive function. When women require bilateral oophorectomy (removal of ovaries), they subsequently have a significant drop in serum testosterone levels. They also frequently experience a decreased sense of well being, and decreased sexual function.

While treatment with testosterone and other androgens has been widely promoted for women with low serum levels, there is little available data on the effects of such treatment particularly when given in physiologic doses (doses resulting in normal blood levels for women). Studies that have demonstrated benefits of testosterone in women have often used doses of testosterone which resulted in higher than normal serum testosterone levels. At such doses, testosterone and other androgens can produce virilizing side effects such as increased facial and body hair, acne, increased size of the clitoris and changes in the voice.

It is not known whether physiologic testosterone replacement can provide the benefits seen with higher doses in women with androgen deficiency without the limiting, virilizing side effects. It has been assumed that testosterone dose-response relationships are different in women than in men, and that clinically significant effects on psycho-sexual function, body composition, muscle performance, cognitive function, and other health-related outcomes can be achieved at testosterone doses and concentrations that are substantially lower than those required to produce similar effects in men; however, these assumptions have not been tested rigorously.

Therefore, the primary objective of this study is to establish testosterone dose-response relationships in surgically menopausal women with low testosterone concentrations for a range of androgen-dependent outcomes, including sexual function, fat-free mass, thigh muscle strength and leg power, several domains of neurocognitive function, plasma lipids, apolipoproteins and lipoprotein particles, and insulin sensitivity.

The secondary objective is to determine the range of testosterone doses and subsequent plasma testosterone concentrations that are associated with improvements in sexual, physical and neurocognitive functions and that can be safely administered to women without significant adverse effects on hair growth, voice, sebum production, clitoral size, and cardiovascular risk factors.

Hypotheses

1. Testosterone administration in surgically menopausal women with low testosterone concentrations is associated with dose- and concentration-dependent improvements in sexual function and sexual activity scores, specific domains of cognitive function, fat-free mass, thigh muscle strength, and leg power.
2. Testosterone dose-response relationships are different for different androgen dependent processes. While some domains of sexual function are normalized by testosterone concentrations at the upper end of the normal range for healthy, young women, significant gains in fat-free mass, thigh muscle strength and power would require higher testosterone doses than those required to induce changes in sexual function.

Inclusion Criteria

• Medically stable, ambulatory, surgically menopausal women, 21-60 years of age, who have undergone bilateral salpingo-oophorectomy and hysterectomy at least 6 months before study entry
• Serum total testosterone concentrations less than 31 ng/dL or free testosterone less than 3.5 pg/ml (less than the median for healthy, young women
• Able to understand and give informed consent.
• The women will have been on a stable regimen of transdermal estrogen replacement for at least three months. Those who are not on estrogen replacement or are taking a different mode of estrogen replacement will be included only if they are willing to switch to transdermal estradiol patch (see below).
• A normal PAP smear (if subject has a cervix) and mammogram in the preceding 12 months.

Exclusion Criteria:

• Significant depression, as assessed by Beck's Depression Scale.
• Any acute or chronic illness, malignant disease or fever of known or unknown origin will be excluded.
• Poorly controlled diabetes mellitus (hemoglobin A1c greater than 8.5%)
• Uncontrolled hypertension defined as blood pressure of greater than 160/100
• Severe obesity defined as body mass index of greater than 40 kg/m2
• Current or recent (last 6 months) users of illicit drugs (which may affect appetite, food intake, metabolism, and/or compliance with the protocol)
• Any one planning to initiate a weight-reduction diet in the subsequent six months
• Alcohol or drug dependence currently or in the preceding 6 month.
• Significant liver function abnormalities, defined as SGOT, SGPT or alkaline phosphatase value of greater than three times the upper limit of normal in our Clinical Pathology Laboratory or serum bilirubin levels of greater than 1.5 mg/dl will be excluded.
• History of breast, ovarian, endometrial or cervical cancer
• History of hyperandrogenic disorders such as hirsutism, grade 2 or 3 acne, and polycystic ovary disease. Testosterone administration to these patients may exacerbate the underlying disorder.
• Intolerance to other transdermal formulations
• Women with abnormal PAP smears or mammograms will not be included unless they have been evaluated by their gynecologists and breast and uterine/cervical cancers have been excluded by appropriate tests.
• Women with dementia as assessed by the mini-mental state examination
• Women with depression, assessed by Beck's Depression Scale.
• Those with disabilities that would prevent them from participating in strength testing (e.g., amputation of limbs, blindness, severe arthritis, neurologic disorders such as Parkinson's disease, stroke, or myopathy).
• Women with any heart disease, including angina, congestive heart failure, or history of myocardial infarction or coronary artery angioplasty or bypass surgery in the previous year will be excluded.
• Subjects planning to initiate a weight-reduction diet in the subsequent six months
• Other Medications. Women who have received in the preceding three months drugs known to affect testosterone production or metabolism such as ketoconazole, Megace, and/or anabolic/androgenic steroids will be excluded. We will also exclude women who are taking or have taken in the past three months medication that include sexual dysfunction (e.g., spironolactone, SSRIs, GnRH agonists). Women who are using any medication, device or dietary supplement known to enhance sexual function will not be included. Women receiving thyroid hormone replacement therapy may participate in the study only if they have been on a stable replacement dose of L-thyroxine for at least three months.
• Intolerance to estrogen products or skin patches
• Undiagnosed vaginal or vulvar bleeding
• History of deep vein thrombosis, pulmonary embolism, or other thromboembolic disorder