There are two enzymes which decide what happens to your testosterone as it leaves the body: 5-alpha reductase turns it into DHT, which is several times more potent than testosterone; and 5-beta reductase turns it into much weaker metabolites. Which route your body favours explains why two women with identical testosterone can have completely different symptoms.
Acne, hair thinning and unwanted hair growth often get blamed on high testosterone, but can also be due to a strong 5-alpha preference (even when testosterone levels are normal).
If you have not tested yet, we measure both pathways in all three FUTURE WOMAN tests.
Let’s take a closer look at what the 5α-reductase pathway is, why optimal levels matter, and how it can impact your health.
Understanding the 5α-Reductase vs. 5β-Reductase Pathways
One of the most important processes in androgen metabolism is the conversion of testosterone into its metabolites (the way the body removes this hormone from the body) through two distinct enzymatic pathways: 5α-reductase and 5β-reductase. Understanding the balance between these two pathways can provide insight into hormonal health, androgen-related symptoms, and metabolic function.
| Before we dive in, it is important to note that women can be misdiagnosed with PCOS/PMOS (usually via ultrasound alone) and instead have normal androgen levels but a preference for the 5a-reductase pathway that is causing PCOS-like symptoms. |
5α-Reductase
The 5α-reductase enzyme converts testosterone into 5α-dihydrotestosterone (5α-DHT), a hormone that is around 3-5 times more potent than testosterone. In women, this conversion primarily occurs in tissues such as the skin, hair follicles and adrenal glands. This enzyme is also responsible for metabolising progesterone and cortisol.
Because 5α-DHT binds more strongly to androgen receptors than testosterone, it plays a critical role in:
- Regulating libido and mood
- Building muscle mass and bone density
- Maintaining red blood cell production
- Influencing secondary sexual characteristics (e.g., hair growth, fat distribution)
Additionally, 5α-Androstanediol, a downstream metabolite of DHT, acts as both a marker of androgen activity and a regulator of hormone balance. While less potent than DHT, elevated levels can indicate increased androgen metabolism, particularly in women undergoing hormone therapy or suffering from androgen-dominant conditions.
5β-Reductase
Unlike the 5α pathway, the 5β-reductase enzyme converts testosterone and DHT into less androgenic metabolites, such as 5β-Androstanediol. These compounds exhibit significantly weaker androgenic activity, reducing the risk of symptoms associated with excess androgens.
Women with high testosterone or DHEA levels but a preference for the 5β pathway may not exhibit strong androgenic symptoms, despite elevated androgen precursors, making this a preferred pathway.
Additionally, 5β-Androstanediol exhibits mild estrogenic activity, binding to estrogen receptors ERα and ERβ in tissues such as the ovaries and uterus, potentially influencing estrogen balance and menstrual health.
Symptoms of high 5a reductase enzyme levels
At FW we look at levels of 5a-reductase metabolism as a percentage compared to 5b reductase.
- The optimal reference range for 5α pathway metabolites is 6–30 ng/mg
- The optimal reference range for 5β pathway metabolites: 20–75 ng/mg
Your results will show if you have a high, low or balanced metabolism of 5α reductase activity.
Symptoms of high 5a metabolism include;
- Hirsutism (excessive facial and body hair growth)
- Scalp hair loss (female pattern baldness)
- Acne and oily skin
- Weight gain
- Fertility issues
- Lack of ovulation
A preference for the 5α reductase pathway may be due to;
- Genetics
- Inflammation
- Dysregulated blood sugar and insulin resistance
- Obesity and excess adipose tissue
- DHEA supplementation
- PCOS
- Toxin exposureÂ
Addressing the underlying causes can help balance out the alpha and beta pathways which in turn can help improve the symptoms that you are experiencing.
We test your 5α-reductase and 5β-reductase activity alongside other androgen markers to look at your whole androgen picture. These include;
- Testosterone (as the precursor to DHT)
- DHT levels (to assess active androgenic load)
- DHEA (which can convert into testosterone and DHT)
- Estrogen markers (if estrogen-modulating effects are suspected)
Which tests measure 5-alpha and 5-beta activity?
Both pathways are measured in all three of our tests: the Classic Hormone Test, the Advanced Hormone Test and the Advanced+ Hormone Test with Cycle Mapping.
If you are not sure which test you need, our comparison guide walks through the differences.
Next steps
If your results suggest high 5α-reductase levels, this will be addressed in your personalised health plan by one of our experienced nutritionists. If you would like to learn more about your test results, remember you can purchase a 45 minute Hormone Health Consultation with your practitioner to discuss your results in more detail.
References
Fassnacht, M., Schlenz, N., Schneider, S. B., Wudy, S. A., Allolio, B., & Arlt, W. (2003). Beyond adrenal and ovarian androgen generation: Increased peripheral 5 alpha-reductase activity in women with polycystic ovary syndrome. The Journal of clinical endocrinology and metabolism, 88(6), 2760–2766. https://doi.org/10.1210/jc.2002-021875
Moghetti, P., Castello, R., Magnani, C. M., Tosi, F., Negri, C., Armanini, D., Bellotti, G., & Muggeo, M. (1994). Clinical and hormonal effects of the 5 alpha-reductase inhibitor finasteride in idiopathic hirsutism. The Journal of clinical endocrinology and metabolism, 79(4), 1115–1121. https://doi.org/10.1210/jcem.79.4.7962284
Wu, C., Wei, K., & Jiang, Z. (2017). 5α-reductase activity in women with polycystic ovary syndrome: a systematic review and meta-analysis. Reproductive biology and endocrinology : RB&E, 15(1), 21. https://doi.org/10.1186/s12958-017-0242-9
