Contrary to popular belief, testosterone isn't just a "male hormone". It's a vital player in women's health, influencing everything from mood to muscle mass. Like men, women experience a natural decline in testosterone levels as they age—a fact often overlooked by conventional medicine.

At Superpower, we recognize the unique challenges of measuring and interpreting testosterone levels in women. Drawing on emerging clinical research, we've established a more precise optimal range specifically for women. This approach allows us to catch deficiencies early and optimize your health, not just maintain it.

Key Points

• Beyond the "Male Hormone": Testosterone is crucial for women's health, affecting multiple bodily systems and declining with age, similar to men.
• Flawed Testing and Reference Ranges: Conventional testing methods lack sensitivity for women's lower testosterone levels, and current "normal" ranges often mask deficiency symptoms, leading to under-diagnosis and missed treatment opportunities.
• Optimal Range: Emerging research suggests a more precise optimal range that correlates with improved cardiovascular health, body composition, cognitive function, and overall well-being in women.
  • Optimal range: 35-60 ng/L
  • Conventional range: 0 – 55.0 ng/L

Health Note: Understanding the role of testosterone in women’s health is challenging. The complex relationship between hormones and very different testing methods, some of which are unreliable for detecting low concentrations found in women, make interpreting the results difficult. As development progresses, so will our understanding.

What is Testosterone?

Testosterone is a key sex hormone, known as an androgen, that plays a crucial role in both men and women ^{[1, 2]}. In women, testosterone is produced in three main areas: roughly 25% comes from the ovaries, another 25% from the adrenal glands, and the remaining 50% is made when other hormones are converted into testosterone in tissues like the skin, liver, and fat cells. This differs from men, who produce most of their testosterone in the testicles.

Once in the bloodstream, most circulating testosterone will stick to proteins like albumin and sex hormone-binding globulin (SHBG), which help transport it throughout the body. About 40% of testosterone will be loosely attached to albumin, while a small portion will remain unbound—this is known as "free testosterone". The free and albumin-bound forms are the more "bioavailable," that means they are readily usable by the body. All these forms together—SHBG-bound, albumin-bound, and free—make up what we call "total testosterone" ^[3].

Interestingly, just like in men, women’s testosterone levels decrease with age. This decline usually begins in the 30s and continues gradually, with a significant drop during menopause. Research shows that 10 years after menopause, testosterone levels can be about half of what they were before ^{[4, 5]}.

What is the Function of Testosterone in Women?

Although often termed the "male hormone" due to its role in male development, testosterone is actually the most abundant biologically active hormone in women, despite women producing 15 to 25 times less testosterone than men ^[6].

In women, testosterone is crucial for maintaining sexual desire and libido ^[7]. It helps keep vaginal tissues healthy and promotes lubrication and blood flow ^[7-9]. Testosterone also supports early egg development in the ovaries and is used to make estradiol, a potent form of estrogen essential for hormonal balance ^[10]. This becomes increasingly important during and after menopause as estrogen levels drop.

Heart disease risk increases after menopause, partly due to changes in body composition ^[11]. The transition often brings an increase in fat around organs. Testosterone's role here is complex: normal levels maintain lean muscle mass, while high levels are linked to more organ fat ^[12]. When testosterone levels aren't balanced, it can disrupt how the body handles sugar and responds to insulin, the hormone that controls blood sugar. High levels of insulin can cause the ovaries to produce more testosterone and impair normal ovulation ^{[13, 14]}.

Testosterone plays a vital role in bone health by promoting mineral accumulation and increasing bone density, which helps prevent conditions like osteoporosis ^[15-17]. This function becomes increasingly important as women age and bone loss accelerates. It also supports red blood cell production in bone marrow, vital for maintaining adequate oxygen supply to tissues ^[18]. This is particularly important for women, who naturally have lower red blood cell and hemoglobin levels than men.

In the brain, testosterone strengthens nerve networks that contribute to mental sharpness and spatial skills, and supports blood flow, which may protect against memory loss ^{[19, 20]}. It also helps balance mood by regulating serotonin and boosting dopamine, the brain's "feel-good" chemicals ^[21].

As women age and testosterone levels gradually decline, this can lead to loss of muscle, weaker bones, increased fat storage, and reduced sensitivity to insulin—conditions that increase the risk of heart and metabolic issues.

Due to sex-specific differences between the concentration and function of testosterone, these ranges are optimised for FEMALES. To learn more about testosterone for MALES click here.

What is the Conventional Reference Range for Testosterone in Women?

The “normal” range of testosterone is difficult to define as most testing methods are not able to accurately measure the low concentration found in women ^[22]. Moreover, testing methods very greatly between labs and lack a unified unit of measure making comparisons difficult ^[23]. The “normal” range however is usually defined as:

Total Testosterone:

• Conventional Range (pre-menopause):  0 – 55.0 ng/L
• Conventional Range (post-menopause):  0 – 40.0 ng/L

Free Testosterone:

• Conventional Range: 10 – 4.0 pg/mL

What is the Superpower Optimal Range for Testosterone in Women?

At Superpower we recommend a narrower range for total and free testosterone:

• Total Testosterone - Superpower Optimal Range: 35 – 60 ng/L
• Free Testosterone - Superpower Optimal Range: 2.1 – 4.2 pg/mL

Our optimal ranges aim to maximize well-being and are based on clinical research that shows better health outcomes at the higher-end of normal.

Health Note: When assessing testosterone levels in women, it's crucial to also consider DHEA/DHEA-S, SHBG, and estradiol levels. DHEA is a precursor to both testosterone and estrogen, influencing overall sex-hormone activity. SHBG affects how much free testosterone is available for the body to use, while estradiol interacts closely with testosterone, impacting its effects throughout the body.

Why is the Conventional Range for Testosterone Problematic?

Measuring testosterone in women is difficult due to the very low concentrations. Standard testing methods, originally designed for male physiology, often lack the sensitivity required to accurately detect these lower levels in women. This results in inconsistent and unreliable measurements ^{[24 - 29]}. Moreover, the absence of a unified testing method further complicates diagnosis.

Historically, testosterone was considered of secondary importance in women's health, leading to underrepresentation in research studies. This bias, combined with the use of male-oriented testing methods have contributed to a porrly defined reference ranges. Only recently, with the development of more accurate testing methods, has the critical role of testosterone in women's health become apparent ^{[30 - 32]}.

Research shows that women with testosterone levels at the lower end of “normal” often experience adverse health outcomes.

Low testosterone levels increase the risk of metabolic syndrome, which in turn raises the likelihood of heart disease, stroke, and type 2 diabetes ^{[33, 34]}. Interestingly, an optimal range for testosterone in cardiovascular health seems to exist. Levels below approximately 30 ng/L and above 60 ng/L are associated with increased risk of coronary heart disease events ^{[35 - 38]}. Moreover, testosterone levels below about 25 ng/L have been linked to higher all-cause mortality and cardiovascular disease risk across all ages ^[35].

Women with lower testosterone levels are more likely to have poor body composition, including lower lean muscle mass ^[39]. This can contribute to frailty and an increased risk of injuries ^{[40, 41]}. Additionally, even "normal" low testosterone levels are associated with lower bone mineral density ^[42]. These effects are particularly pronounced post-menopause, when both estrogen and testosterone levels decline ^[40].

Testosterone plays a crucial role in mood regulation and cognitive function. Women with lower testosterone levels, even within the "normal" range, are more likely to experience depressive symptoms and report lower overall well-being. This is especially true for postmenopausal women ^{[43, 44]}.

Low testosterone levels in the lower quartile predict death from all causes, particularly in individuals with higher blood sugar ^[45]. This underscores the far-reaching implications of testosterone levels on overall health and longevity.

Women with testosterone levels on the lower end of “normal” already experience symptoms of deficiency—such as fatigue, low libido, and muscle weakness— but, these risks are not adequately addressed by current reference ranges as their levels are "normal" ^[46].

Supporting Evidence for the Optimal Range

Testosterone levels within the range of 35-60 ng/L have been linked to several important health benefits in women. However, it's crucial to note that defining a true optimal range has been challenging due to historically insensitive testing methods, incompatible assays, and a male-centric understanding of testosterone. Much of our current understanding comes from interventional studies and testosterone replacement therapies.

For heart health, maintaining sufficient testosterone appears crucial. A study of postmenopausal women  found that those with the lowest total testosterone had a 62% increased risk of heart problems. This  was independent of age, body fat, and lifestyle ^[36]. Additionally, postmenopausal women with lower testosterone showed thickening of blood vessels – a marker of future heart attack risk ^[47]. Higher testosterone levels are associated with improved blood vessel structure and function ^[48]. It enhances the flexibility of blood vessels and supports the relaxation of the heart between beats. Chronically low levels can impair these functions ^[48-50]. This suggests a protective effect of higher testosterone levels.

Studies found that women with total testosterone levels between 35-55 ng/dL reported better sexual function, increased muscle strength, and improved overall well-being ^{[30, 31]}. Moreover, maintaining testosterone within this range could enhance bone density and reduce the risk of fractures ^{[15-17, 51]}.

Brain health appears to benefit from higher testosterone. Fifteen studies examining low testosterone (<31 ng/L) showed an increased risk of cognitive decline and dementia [52]. Testosterone has been shown to improve the brain's ability to make new connections, potentially enhancing memory, decision-making skills, and mental clarity. Furthermore, testosterone may slow the aging process of cells lining blood vessels, leading to slower brain aging. In terms of metabolic health, the same studies showed an increased risk of metabolic syndrome and poor blood sugar and cholesterol control with low testosterone levels ^[52].

Additionally, women who had total and free testosterone in the lower end of the "normal" range were more likely to have anemia – a condition where there aren't enough healthy red blood cells to carry adequate oxygen to the body's tissues. Levels under 46 ng/L were still associated with a higher likelihood of anemia ^[53].

However, it's important to note that very high levels of testosterone in women can also have negative effects. Elevated levels of advanced glycation end products (AGEs) - markers of oxidative stress - were observed in women with testosterone levels of 53-60 ng/dL versus those with levels of 23-52 ng/dL ^[23]. This indicates that there may be an upper limit to the beneficial effects of testosterone in women.

Key Takeaway

Testosterone is often labeled as the "male hormone," but it's crucial for women's health too. Like men, women not only benefit from testosterone's wide-ranging physiological effects but also experience a decline in levels with age. However, defining an optimal range for women has been challenging due to inadequate testing methods and inconsistent lab standards.

At Superpower, our approach is rooted in emerging research that points to a more precise optimal range. Studies suggest that total testosterone levels of 35-60 ng/L in women correlate with better cardiovascular health, improved body composition, sharper cognitive function, and enhanced overall well-being. We're not just preventing deficiency - we're aiming for true optimization.