What causes low testosterone in women?

Causes of Low Testosterone in Women

Low testosterone in women can result from various conditions affecting the hypothalamic-pituitary-ovarian axis, adrenal function, and peripheral hormone metabolism. Understanding these causes is essential for proper diagnosis and management of symptoms that may include fatigue, decreased libido, reduced muscle mass, and impaired cognitive function.

Primary Causes of Low Testosterone in Women

Ovarian Factors

• Advanced age and menopause: Testosterone levels naturally decline with age, with a significant drop (approximately 50%) occurring around ages 42-47, even before menopause 1
• Premature ovarian failure: Results in decreased ovarian production of testosterone 2
• Oophorectomy (surgical removal of ovaries): Eliminates a major source of testosterone production 2
• Polycystic ovary syndrome (PCOS) treatment: Medications used to treat PCOS can reduce testosterone levels 3, 4
  • Oral contraceptives containing estrogen increase sex hormone-binding globulin (SHBG), reducing free testosterone 3
  • Non-steroidal anti-inflammatory drugs like ibuprofen can selectively reduce testosterone levels 4

Adrenal Factors

• Adrenalectomy: Surgical removal of adrenal glands eliminates an important source of testosterone 2
• Adrenal disease: Conditions affecting adrenal function can impair testosterone production 2
• Chronic corticosteroid use: High-dose corticosteroids suppress adrenal androgen production 2

Hypothalamic-Pituitary Disorders

• Pituitary disorders: Conditions affecting the pituitary gland can disrupt the production of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which stimulate ovarian testosterone production 5, 2
• Hyperprolactinemia: Elevated prolactin levels can suppress gonadotropin secretion, leading to reduced testosterone production 5

Liver Disease

• Chronic liver disease: Can alter sex hormone-binding globulin (SHBG) levels, affecting free testosterone availability 5
• Altered estrogen metabolism: Liver dysfunction can impair estrogen metabolism, affecting the estrogen-testosterone balance 5

Other Medical Conditions

• HIV infection: Associated with reduced testosterone levels in women 2
• Turner's syndrome: Genetic condition resulting in ovarian dysgenesis and reduced testosterone production 2
• Epilepsy: Women with epilepsy have a higher prevalence of reproductive endocrine disorders that can affect testosterone levels 5
• Diabetes: Type 2 diabetes is associated with hormonal imbalances that can affect testosterone levels 5

Diagnostic Considerations

When evaluating a woman for low testosterone:

1. Measure morning total testosterone levels using accurate and reliable assays 5
2. Assess free testosterone either through direct measurement or calculation using total testosterone, SHBG, and albumin concentrations 5
3. Measure LH/FSH levels to determine if the cause is primary (ovarian) or secondary (pituitary) 5
4. Check prolactin levels if LH/FSH levels are low or low-normal 5
5. Evaluate for PCOS through clinical features, hormone levels, and pelvic ultrasound 5

Clinical Pearls and Pitfalls

• Diagnostic challenge: Lack of precise definitions and sensitive assays for testosterone in women makes diagnosis difficult 6
• Normal ranges: Precise normal ranges for female testosterone are poorly established, complicating interpretation 6
• SHBG fluctuations: Changes in SHBG (due to oral contraceptives, liver disease, etc.) can affect free testosterone levels without changing total testosterone 5, 3
• Diurnal variation: Testosterone levels should be measured in the morning due to significant diurnal variation 5
• Age-related changes: Consider age-appropriate reference ranges, as testosterone levels naturally decline with age 1

Understanding these various causes of low testosterone in women is crucial for proper diagnosis and management, as testosterone plays important roles in sexual function, bone density, muscle mass, energy levels, cognitive function, and mood.