PCOS and Oestrogen: The Hidden Hormonal Imbalance You Need to Know About

When we think about polycystic ovary syndrome (PCOS), we often focus on the elevated testosterone levels associated with the condition. But did you know that PCOS also involves imbalances in oestrogen? In fact, women with PCOS often experience prolonged exposure to high levels of oestrogen due to an extended follicular phase. This extended phase can contribute to many of the symptoms associated with PCOS.

Let’s take a closer look at how oestrogen plays a significant role in PCOS, how this prolonged follicular phase leads to oestrogen dominance, and why it’s important to consider hormonal balance beyond just testosterone.

 

PCOS: It’s More Than Just High Testosterone

Yes, elevated testosterone is a hallmark of PCOS, but it’s not the only hormone at play. In women with PCOS, the menstrual cycle is often disrupted. Specifically, the follicular phase, which is the first half of the cycle where oestrogen rises to prepare for ovulation, can become much longer than normal. When ovulation doesn’t occur regularly or at all, the body experiences a prolonged period of high oestrogen without the counteracting effects of progesterone, which rises after ovulation, released from the corpus luteum.

This extended exposure to oestrogen contributes to many of the symptoms experienced by those with PCOS, but aren’t always easy to be explained by the evelated levels of insulin and testosterone. So keep in mind it’s not just about high testosterone—oestrogen plays a big role, too!

 

Signs of Excess Oestrogen in PCOS

If you have PCOS, you might be familiar with some of the signs of oestrogen dominance, such as:

• Breast tenderness
• Heavy or prolonged periods
• Bloating or water retention
• Mood swings and irritability
• Weight gain, especially around the hips and thighs

These symptoms are the result of an imbalance between oestrogen and progesterone. When oestrogen is allowed to remain elevated for too long without progesterone to balance it out, you may start to notice these classic signs of oestrogen dominance.

 

The Phases of the Menstrual Cycle

To understand how oestrogen dominance happens in PCOS, let’s briefly review the phases of a normal menstrual cycle:

1. Menstrual Phase – This is when you get your period, and the uterine lining is shed.
2. Follicular Phase – Oestrogen rises as your body prepares for ovulation. For many women with PCOS, this phase can be prolonged.
3. Ovulation – Ideally, a mature egg is released during ovulation. Oestrogen needs to peak in order to trigger a surge of LH, which then triggers the egg to be released from the follicle. For many women with PCOS, ovulation doesn’t occur regularly, leading to what’s called an anovulatory cycle, or an extended follicular phase.
4. Luteal Phase – After ovulation, the remainder of the follicle from which the egg from release – the corpus luteum – releases progesterone. Progesterone levels rise in the luteal phase, which balances the effects of oestrogen. However, if ovulation doesn’t happen, there’s no significant rise in progesterone, leading to relative oestrogen excess.

 

In PCOS, it’s common to have anovulatory cycles, meaning ovulation doesn’t occur, and the body doesn’t produce the necessary progesterone to balance out the high oestrogen levels. This leaves many women stuck in an extended follicular phase with prolonged exposure to oestrogen.

 

How Testosterone Can Convert to Oestrogen

Another important factor to consider in PCOS is how testosterone can be converted into oestrogen. This happens through a process called aromatisation, where testosterone is transformed into oestrogen in the body’s tissues, including fat cells. For women with PCOS, who often have elevated levels of testosterone, this can result in more oestrogen being produced, contributing further to the oestrogen dominance that many experience (Xu et al., 2024).

 

Increased Sensitivity to Oestrogen in PCOS

Interestingly, not only are oestrogen levels higher for longer in many women with PCOS, but there’s also evidence to suggest that their oestrogen receptors are more sensitive. This means that even if the levels of oestrogen aren’t dramatically high, the body may respond more strongly to it, intensifying the symptoms of oestrogen dominance (Xu et al., 2024). This heightened sensitivity further contributes to the hormonal imbalance that can make PCOS so challenging to manage.

 

The Impact of Endocrine Disrupting Chemicals (EDCs)

As if managing PCOS wasn’t complex enough, exposure to endocrine-disrupting chemicals (EDCs), such as bisphenol A (BPA), can further complicate the hormonal picture. Research has shown that women with PCOS often have elevated levels of BPA in their plasma, urine, or follicular fluid. BPA can mimic oestrogen and bind to oestrogen receptors, increasing their activity. This leads to more pronounced symptoms of oestrogen dominance and is linked to insulin resistance, polycystic ovarian morphology on ultrasound, and even markers of chronic low-grade inflammation (Srnovršnik et al., 2023).

If you have PCOS and are concerned about environmental factors like EDCs, it’s worth considering ways to reduce your exposure to BPA and other hormone disruptors, as these chemicals may worsen the hormonal imbalances associated with the condition.

Read more about endocrine disrupting chemicals and their impact on hormones and fertility here and here

 

Low SHBG Levels in PCOS and Its Effect on Oestrogen and Testosterone

Another key factor in PCOS is the role of sex hormone-binding globulin (SHBG). SHBG is a protein that binds to hormones like oestrogen and testosterone, controlling how much of these hormones are “free” and active in the body. Women with PCOS tend to have low SHBG levels, meaning they have more free (unbound) oestrogen and testosterone circulating in the bloodstream. This not only contributes to higher androgen symptoms (like acne and male pattern hair loss) but also increases the effects of oestrogen on the body (Emanuel et al., 2022).

 

Want to Learn More About PCOS?

If you’re dealing with PCOS and want to dive deeper into understanding how these hormonal imbalances affect your health, I’ve written several other blog posts on this topic. Check them out here:

Busting PCOS Myths

A Holistic Guide to PCOS

If you’d like to know more about hormones and how they affect your health and wellbeing, and how you can support your hormonal wellbeing and cyclical health, I would love you to look into my e-course The Cyclical Woman

 

Final Thoughts

PCOS is a complex condition that involves more than just high testosterone. The extended follicular phase, lack of progesterone due to anovulation, increased aromatisation of testosterone to oestrogen, and heightened oestrogen receptor sensitivity all contribute to the hormonal imbalances experienced by those with PCOS. By understanding how oestrogen plays into the bigger picture, you can take steps to manage your symptoms more effectively and work towards achieving better hormonal balance.

References

Emanuel, R. H. K., Roberts, J., Docherty, P. D., Lunt, H., Campbell, R. E., & Möller, K. (2022). A review of the hormones involved in the endocrine dysfunctions of polycystic ovary syndrome and their interactions. Frontiers in Endocrinology (Lausanne), 13, Article 1017468. https://doi.org/10.3389/fendo.2022.1017468

Srnovršnik, T., Virant-Klun, I., & Pinter, B. (2023). Polycystic ovary syndrome and endocrine disruptors (bisphenols, parabens, and triclosan) – A systematic review. Life (Basel), 13(1), 138. https://doi.org/10.3390/life13010138

Xu, Y., et al. (2024). Roles of estrogen and its receptors in polycystic ovary syndrome. Frontiers in Cell and Developmental Biology, 12, Article 1395331. https://doi.org/10.3389/fcell.2024.1395331