Explore 10,000+ laboratory markers, in plain English.

a vital biomarker used to evaluate hormonal health

What is % Free Testosterone (Dialysis)? % Free Testosterone (Dialysis) measures the percentage of total testosterone in your bloodstream that is not bound to proteins like sex hormone-binding globulin (SHBG) or albumin. This test uses a dialysis-based method, which is considered the gold standard for accurately quantifying free testosterone — the biologically active form of the hormone. In your blood, most testosterone is attached to proteins, which helps transport it through your body. But only a small fraction — known as “free testosterone” — is unbound and bioavailable, meaning it can directly interact with cells and carry out essential hormonal functions. The “percent free testosterone” tells you how much of your total testosterone is in this usable, free form. Why is % Free Testosterone Important? Free testosterone plays a critical role in regulating: Libido and sexual function Muscle mass and strength Bone density Mood and cognitive performance Red blood cell production Fat distribution and metabolism A normal percentage of free testosterone ensures that your body is able to respond appropriately to hormonal signals, especially in tissues like the brain, muscles, and reproductive organs. It’s particularly useful when total testosterone levels are borderline or when symptoms suggest a hormone imbalance. What is the Dialysis Method? The equilibrium dialysis method separates free testosterone from protein-bound forms by using a membrane that mimics the way substances naturally pass through cell membranes. This is a highly sensitive and specific method that directly measures the actual free testosterone, unlike some calculations or indirect methods (like analog-based assays) that may produce inaccurate results, especially in individuals with abnormal SHBG levels. What Do Abnormal % Free Testosterone Levels Mean? Elevated % Free Testosterone A higher-than-normal percentage of free testosterone may indicate: Polycystic Ovary Syndrome (PCOS) in women Androgen-secreting tumors (rare) Congenital adrenal hyperplasia (CAH) Steroid use or abuse Low levels of SHBG (common in obesity, insulin resistance, or hypothyroidism) Decreased % Free Testosterone A low percentage of free testosterone may suggest: Male hypogonadism (low testosterone production) Aging-related testosterone decline Chronic illness or stress Elevated SHBG (can occur with liver disease, hyperthyroidism, or estrogen therapy) Obesity or metabolic syndrome Even if your total testosterone level is in the normal range, your free testosterone could be low — and that’s often when symptoms appear. Who Should Get This Test? This test is often ordered when someone has symptoms of testosterone imbalance but a normal or borderline total testosterone level. It is especially useful for: Men with signs of low testosterone (fatigue, low libido, depression, muscle loss) Women with signs of high testosterone (acne, hirsutism, irregular periods) Individuals with abnormal SHBG levels Monitoring response to testosterone replacement therapy (TRT) Evaluating hormonal health in aging men or athletes What’s a Normal % Free Testosterone Range? Reference ranges can vary by lab, but typical values are: Men: 1.5% – 3% of total testosterone Women: 0.3% – 1.9% of total testosterone These values should always be interpreted alongside total testosterone, SHBG, and your clinical symptoms. Final Thoughts Testing % Free Testosterone by Dialysis offers a more precise understanding of your hormone health than total testosterone alone. It helps identify subtle hormone imbalances that might otherwise be missed — especially when protein-binding changes are involved. If your results are abnormal, follow up with a healthcare provider to investigate further and discuss treatment or lifestyle strategies.

DHT

5A-DHT is converted from testosterone by 5-α reductase in the ovaries and peripherally in fat tissue.

Dihydrotestosterone (DHT) is a key androgenic marker providing critical insights into androgen metabolism and its implications in female health. DHT, a biologically active metabolite of testosterone, is formed primarily in peripheral tissues through the action of the enzyme 5-alpha-reductase. Despite being commonly associated with male physiology, DHT plays a significant role in women, particularly in hair follicle health, skin condition, and overall hormonal balance. Elevated levels of DHT in women can lead to androgenic effects such as hirsutism (excessive hair growth in areas typical for males), acne, and in some cases, androgenic alopecia (pattern hair loss). These symptoms are often observed in conditions like polycystic ovary syndrome (PCOS), which is characterized by an overproduction of androgens. In the context of a urine comprehensive hormone panel, measuring DHT levels allows for a nuanced understanding of androgenic activity over time. This is especially important in diagnosing and managing conditions where androgen levels fluctuate, such as in different phases of the menstrual cycle or in response to hormonal therapies. Elevated urinary DHT levels in females may warrant further investigation to determine underlying causes, which can include not only PCOS but also adrenal hyperplasia or tumors, insulin resistance, and obesity. Treatment for elevated DHT levels typically focuses on addressing the underlying hormonal imbalance. This might involve lifestyle interventions like diet modifications and exercise to improve insulin sensitivity and reduce body weight, as obesity can exacerbate androgenic symptoms. Pharmacological treatments can include androgen receptor blockers, 5-alpha-reductase inhibitors to reduce the conversion of testosterone to DHT, or hormonal contraceptives to regulate menstrual cycles and reduce androgen production. Each treatment plan should be personalized based on the individual's specific hormonal profile, health status, and the severity of symptoms. Monitoring DHT levels alongside other hormonal markers is crucial in evaluating the effectiveness of these treatments and ensuring a holistic approach to managing hormonal health in women.

Potent androgen measured to assess excess androgens in females.

Dihydrotestosterone (DHT), the potent androgen made from testosterone.

Hormone test

Hormone test

Naturally-occurring testosterone compound

Epi-Testosterone, an often-overlooked yet significant steroid hormone, is a critical marker in the ZRT Laboratory Urinary Neurotransmitters panel, underlining its relevance in the realm of male health diagnostics. Although chemically similar to testosterone, epi-testosterone functions differently and does not possess the same androgenic properties. In males, epi-testosterone is primarily known as a natural counterbalance to testosterone, maintaining a crucial hormonal equilibrium. Its ratio to testosterone is of particular interest in clinical assessments, as significant deviations from the normal balance can indicate various health issues, including endocrine disorders or potential doping in athletes. In clinical practice, evaluating epi-testosterone levels alongside testosterone provides a more comprehensive view of androgenic activity and hormonal health in men. Low levels of epi-testosterone, or a skewed testosterone to epi-testosterone ratio, can be indicative of hormonal imbalances or dysregulation in steroidogenesis. The inclusion of epi-testosterone in the ZRT Laboratory panel represents a sophisticated approach to male health diagnostics, allowing healthcare professionals to gain deeper insights into hormonal profiles and address potential health concerns more effectively. This marker's assessment is particularly beneficial for men experiencing symptoms of hormonal imbalance or for athletes undergoing hormone monitoring. By offering a nuanced view of androgenic activity through markers like epi-testosterone, the ZRT Laboratory Urinary Neurotransmitters panel stands as an invaluable tool in the field of men's health, aiding in the development of targeted treatment strategies and promoting optimal hormonal well-being.

Unbound testosterone level in serum or plasma

Free Testosterone - Saliva (pg/mL): Understanding the Biomarker Free Testosterone is the bioavailable form of testosterone, a key androgen hormone responsible for regulating numerous physiological processes in both men and women. The Free Testosterone - Saliva test measures the amount of unbound testosterone in saliva, expressed in picograms per milliliter (pg/mL). Unlike total testosterone tests in blood, saliva testing specifically assesses the hormone’s biologically active fraction, which is readily available for use by the body’s tissues. Functions of Free Testosterone In Men: Regulates sexual function and libido. Supports muscle mass, strength, and fat distribution. Influences sperm production and fertility. Contributes to energy levels and cognitive function. In Women: Supports bone health and muscle maintenance. Enhances libido and sexual function. Affects mood, energy, and focus. Why Test Free Testosterone in Saliva? Saliva testing provides a non-invasive and convenient method for assessing bioactive testosterone levels. Since it measures the free (unbound) hormone, it is particularly useful for: Evaluating symptoms of hormonal imbalances or androgen-related disorders. Monitoring the effects of testosterone replacement therapy (TRT) or other hormonal treatments. Assessing circadian testosterone fluctuations, as levels naturally peak in the morning and decline throughout the day. Normal Ranges for Free Testosterone in Saliva The optimal range for free testosterone in saliva varies based on age, sex, and life stage. Typical reference ranges are: Men: ~50 - 150 pg/mL Women: ~10 - 50 pg/mL Postmenopausal women and older men generally exhibit lower levels due to natural hormonal decline. What Do Abnormal Levels Mean? Elevated Free Testosterone Levels: In Men: Potential Causes: Over-supplementation from testosterone replacement therapy (TRT) or anabolic steroids. Hyperactive adrenal glands producing excessive androgens. Rare conditions such as testosterone-secreting tumors. Symptoms: Aggression or irritability, acne, oily skin, increased body hair, and potentially reduced fertility due to suppressed natural testosterone production. In Women: Potential Causes: Polycystic ovary syndrome (PCOS), characterized by excess androgen production. Adrenal hyperplasia or androgen-secreting tumors. Use of certain medications (e.g., steroids or testosterone therapy). Symptoms: Excessive facial/body hair growth (hirsutism), acne, irregular menstrual cycles, and hair thinning or balding. Low Free Testosterone Levels: In Men: Potential Causes: Aging (andropause) with natural hormonal decline. Chronic illnesses (e.g., diabetes, obesity, or metabolic syndrome). Pituitary or testicular dysfunction (e.g., hypogonadism). Symptoms: Low libido, erectile dysfunction, decreased muscle mass, fatigue, depression, and cognitive decline. In Women: Potential Causes: Natural hormonal decline due to menopause. Chronic stress leading to adrenal insufficiency. Use of medications such as oral contraceptives. Symptoms: Reduced libido, low energy, muscle weakness, and difficulty maintaining bone density. Clinical Applications of Free Testosterone Testing Hormonal Imbalance Evaluation: Helps diagnose conditions like hypogonadism in men or androgen excess in women (e.g., PCOS). Monitoring Hormone Therapy: Tracks the efficacy and safety of testosterone replacement therapy (TRT) or other hormonal interventions. Assessing Reproductive Health: Provides insights into fertility challenges in both men and women. Evaluating Age-Related Hormonal Decline: Identifies low testosterone levels associated with andropause or menopause. Factors Influencing Free Testosterone Levels Age: Levels naturally decline with age in both men and women. Stress: Chronic stress elevates cortisol, which can suppress testosterone production. Lifestyle: Poor diet, lack of exercise, and inadequate sleep negatively impact testosterone levels. Medications: Certain drugs (e.g., corticosteroids, opioids) can reduce testosterone levels. Health Conditions: Obesity, diabetes, and chronic illnesses are linked to lower testosterone. How to Optimize Free Testosterone Levels Healthy Lifestyle: Diet: Incorporate foods rich in zinc (e.g., shellfish, seeds), magnesium (e.g., leafy greens), and healthy fats to support hormone production. Exercise: Engage in regular resistance training and high-intensity interval training (HIIT), which boost testosterone levels naturally. Sleep: Aim for 7-9 hours of quality sleep per night, as testosterone production occurs primarily during sleep. Stress Management: Practice relaxation techniques like yoga, meditation, or deep breathing to reduce cortisol levels. Medical Interventions: For clinically low levels, consult a healthcare provider about hormone replacement therapy (HRT) or testosterone supplementation. Avoid Excessive Alcohol or Smoking: Both can suppress testosterone levels and harm overall health. Conclusion The Free Testosterone - Saliva (pg/mL) test offers a valuable, non-invasive way to assess bioavailable testosterone levels, providing insights into hormonal balance and overall health. Whether monitoring therapy, evaluating symptoms of imbalance, or assessing age-related hormonal decline, this test helps guide personalized interventions to optimize well-being. Always consult a healthcare professional to interpret test results and develop a tailored plan for maintaining hormonal health.

Free Testosterone in Women Free testosterone is the unbound, biologically active form of testosterone in the bloodstream. In women, it is typically measured in picograms per deciliter (pg/dL), with a reference range of 0.7 to 2.00 pg/dL. Significance Free testosterone plays a vital role in women's health by contributing to: Muscle strength Bone density Libido regulation Although present in much lower quantities than in men, free testosterone is essential for numerous physiological processes in women. Measurement and Interpretation Free testosterone levels can be assessed through several methods: Equilibrium dialysis – the gold standard for accuracy. Calculation – derived from total testosterone and SHBG using mass action equations. Free Androgen Index (FAI) – an alternative estimate. Direct radioimmunoassay (RIA) methods are less accurate and reliable for women, making equilibrium dialysis or calculated methods the preferred options. Clinical Relevance Abnormal free testosterone levels may indicate underlying health conditions: Elevated levels: Potentially linked to polycystic ovary syndrome (PCOS) or other androgen excess disorders. Low levels: Associated with androgen deficiency, which can affect overall well-being and sexual function. Accurate measurement of free testosterone is essential for the diagnosis and management of these conditions, ensuring effective treatment and better health outcomes.