Tag: normal testosterone levels in women

A new Hertility study reveals that testosterone levels in women change continuously throughout adult life, challenging the idea that one broad reference range can accurately define what is “normal” for every woman at every age (Wainwright et al., 2026). Testosterone is often thought of as a male hormone but women produce it too. It plays an important role in sexual function, mood, muscle mass, bone health, metabolism and wider reproductive physiology (Davis and Wahlin-Jacobsen, 2015). It is also commonly tested when investigating symptoms such as excess facial or body hair, persistent acne, irregular periods, scalp hair loss and possible polyendocrine metabolic ovarian syndrome (PMOS), formerly known as polycystic ovary syndrome (PCOS). But interpreting the result is not always straightforward. Testosterone results are generally compared with a laboratory reference range and labelled as either inside or outside that range. However, many existing ranges are based on relatively small groups of women and use broad age categories. Published in the peer-reviewed Journal of Endocrinological Investigation, Hertility’s study suggests that age should become a much bigger part of how testosterone results are understood. What did the study find? Researchers analysed testosterone levels from 5,323 carefully screened women aged 19-59 from across England, Scotland and Wales. The main finding was clear: average testosterone levels were approximately 1.4% lower with each additional year of age. The amount of variation between women also increased with age. This means testosterone did not simply decline at one defined life stage, such as menopause. Instead, levels changed gradually throughout adult life. In practical terms, the same testosterone result may not mean exactly the same thing for a 22-year-old and a 52-year-old. The researchers therefore developed an age-continuous reference model. Rather than placing women into broad groups such as ages 20-49, which is what one of the current reference ranges does, the model shows how a result compares with the testosterone distribution expected at each individual age. About the research The study retrospectively analysed anonymised data collected through Hertility’s reproductive health service between September 2020 and August 2025. More than 30,000 records were initially available. Strict criteria were then applied to establish a reliable ‘healthy’ reference population. The final reference group included 5,323 women who had regular menstrual cycles, a normal BMI and no reported history of reproductive health conditions or hirsutism (excess hair growth). Samples were collected during the early part of the menstrual cycle, following a fast, and analysed using the same laboratory platform. This helped reduce some of the variation caused by sample timing and different testing methods. A separate group of 2,338 women who reported hirsutism was also assessed. What did the study find about excess facial or body hair? Hirsutism describes the growth of thicker, darker hair in areas such as the face, chest, abdomen or back. It can be a clinical sign of androgen excess and is commonly associated with PMOS, although not everyone with hirsutism will have raised testosterone or PMOS (Escobar-Morreale et al., 2012). The study found that women reporting hirsutism had significantly higher testosterone levels on average than women in the reference population. The difference was most noticeable at younger ages. At age 18, the most typical testosterone level in the hirsutism group was around 24% higher than in the reference group. This difference became smaller with age but remained present throughout adult life. However, there was considerable overlap between the two groups. This is important because it shows why symptoms should not be dismissed simply because a testosterone result is labelled normal. Equally, a raised testosterone result cannot diagnose the cause of someone’s symptoms on its own. Blood results and symptoms need to be interpreted together. What is a normal testosterone level in women? There is no single testosterone level that is universally normal for every woman. The reference range shown on a blood test can vary depending on the laboratory, the testing method and the population used to create it. Testosterone levels can also be influenced by menstrual-cycle timing, time of day, body mass index, stress, hormonal contraception, pregnancy and menopausal stage (Schiffer et al., 2023). Hertility’s findings add age as another essential consideration. A result may fall inside a broad laboratory range while still being relatively high or low compared with what is typically expected for someone of that specific age. It is also important to understand that a reference range is not the same as a diagnostic threshold. A reference range describes the values found in a selected population; it does not create a clear dividing line between health and disease. Why current testosterone reference ranges may be limited One widely used testosterone assay manufacturer established its female reference range using just 149 women, divided into two broad categories: ages 20-49 and ages 50 and over. By comparison, Hertility’s new model was developed using 5,323 carefully selected women and estimated expected testosterone distributions continuously across ages 19-59. Reference ranges may also differ between NHS trusts, private providers and laboratories because testing sites use different platforms or locally established ranges. This means the same testosterone level may be interpreted differently depending on where someone is tested. The study does not propose that clinical decisions should be made from age alone. Instead, it provides greater context to help clinicians understand how common or unusual an individual result is compared with other women of the same age. What does this mean for PMOS? Higher testosterone is commonly associated with PMOS, a complex hormonal and metabolic condition that can affect menstrual cycles, ovulation, skin, hair and fertility. Androgen excess may be identified through visible symptoms, such as hirsutism, or through hormone testing. International guidance recognises both clinical and biochemical signs of androgen excess when assessing someone for PMOS (Teede et al., 2023). The Hertility study does not create a new diagnostic cut-off for PMOS. Instead, it reinforces that a testosterone result within a broad laboratory range does not automatically exclude androgen excess or PMOS – particularly where someone has relevant symptoms or irregular periods. Testosterone should be considered alongside menstrual […]