Testosterone Bioavailable - Female

Introduction

As a Nurse Practitioner with an autonomous practice in Florida, I have seen firsthand the importance of understanding hormone levels, particularly testosterone, in female health. Bioavailable testosterone, a critical biomarker, plays a significant role in several physiological processes and can indicate various health conditions. In this article, we will delve into the background of bioavailable testosterone in females, discuss its clinical implications, identify interfering factors, and explore potential drug interactions that can alter its levels.

Background of Bioavailable Testosterone

Bioavailable testosterone refers to the fraction of testosterone in the blood that is readily available for biological activity. In the context of female health, this biomarker is instrumental in evaluating conditions such as polycystic ovarian syndrome (PCOS), testosterone-producing tumors, and congenital adrenal hyperplasia. Traditionally, it was believed that only free testosterone, not bound to proteins, was biologically active. However, recent findings indicate that testosterone bound to albumin, due to its weak binding, can also dissociate and become available for tissue uptake.

In adult females, testosterone serves various functions. It helps maintain lean body mass, bone density, and skin elasticity, and it plays a crucial role in libido and blood cell production. These functions underline the importance of monitoring bioavailable testosterone levels to ensure optimal health and well-being.

Ranges of Bioavailable Testosterone

The measurement of bioavailable testosterone levels is typically expressed in two units: U.S. units (ng/dL) and International units (nmol/L). The standard range for bioavailable testosterone in females is 0.50 – 8.50 ng/dL (0.02 – 0.29 nmol/L). An optimal range is considered to be between 5.50 – 8.50 ng/dL (0.19 – 0.29 nmol/L).

Testing for bioavailable testosterone is recommended in patients displaying symptoms of masculinization and hirsutism, or for those with suspected ovarian or adrenal dysfunction. It is also useful for screening and monitoring women at risk of or suffering from PCOS.

Clinical Implications of Low Bioavailable Testosterone

Having low levels of bioavailable testosterone in females has been associated with several health issues:

• Osteoporosis: Reduced testosterone can lead to decreased bone density, increasing the risk of fractures.
  
• Decreased Lean Body Mass: Maintaining muscle mass is crucial for overall health, and low testosterone can hinder this.
  
• Decreased Libido: Testosterone is linked to sexual health, and low levels can result in reduced sexual desire.
  
  

Additionally, low testosterone may indicate ovarian or adrenal insufficiency. Levels naturally decrease following menopause, and restoring testosterone levels can help improve well-being and libido.

Clinical Implications of High Bioavailable Testosterone

Conversely, elevated levels of bioavailable testosterone can also lead to health complications:

• Masculinization and Hirsutism: High testosterone can cause excessive hair growth on the face and chest, often indicating PCOS.
  
• Polycystic Ovary Syndrome (PCOS): Elevated testosterone is a hallmark of PCOS, suggesting ovarian or adrenal dysfunction.
  
• Increased Insulin Resistance: High testosterone levels can contribute to metabolic issues, including type 2 diabetes.
  
• Low Estrogen Levels: There is an inverse relationship between testosterone and estrogen, meaning increased testosterone may indicate lower estrogen levels.
  
  

Interfering Factors

Various factors can affect bioavailable testosterone levels, leading to falsely decreased or increased readings. It is crucial to consider these when interpreting results:

• Falsely Decreased Levels: Certain conditions, such as hypopituitarism, can result in decreased testosterone levels.
  
• Falsely Increased Levels: Hyperthyroidism and adrenal tumors can lead to increased testosterone readings.
  
  

Drug Associations

Several medications can influence bioavailable testosterone levels, either decreasing or increasing them:

Drug Causes of Decreased Levels

• Oral Contraceptives: These can lower testosterone levels as part of their mechanism of action.
  
• Other Medications: Cimetidine, gemfibrozil, ketoconazole, metformin, pravastatin, prednisone, spironolactone, tetracycline, and verapamil are known to decrease testosterone levels.
  
  

Drug Causes of Increased Levels

• Endogenous Testosterone Therapy: This therapy can artificially elevate testosterone levels.
  
  

Conclusion

In conclusion, a comprehensive evaluation by a functional medicine telehealth provider integrates bioavailable testosterone testing into a holistic framework that addresses hormonal imbalances and their systemic effects. By combining targeted nutritional support, individualized lifestyle interventions, and evidence-based therapies, this strategy transcends symptomatic management to address root pathophysiology and foster long-term vitality. Contact us at 904-799-2531 or schedule online, and explore our medical weightloss and IV therapy services for advanced hormone optimization.

Further Reading

1. Obesity regulates bioavailable testosterone levels in women with or without polycystic ovary syndrome — Fertility and Sterility
   
2. Measures of bioavailable serum testosterone and estradiol and their relationships with muscle mass, muscle strength and bone mineral density in postmenopausal women — European Journal of Endocrinology
3. Increase of bioavailable testosterone is associated with gain in bone mineral density after cure of primary hyperparathyroidism in postmenopausal women — Clinical Endocrinology (Oxf)