In terms of hormone health, it is not just about an individual hormone’s level. Two different hormones could have “normal” levels, but could be completely imbalanced with respect to one another, which may cause various frustrating and even persistent symptoms. One of the most important relationships of hormones in women’s health involves progesterone and estrogen, and this relationship cannot be understood through the measurement of one hormone alone.
What Is the Pg/E2 Ratio?
The ratio of progesterone to estradiol, also known as the Pg/E2 ratio, is a clinical test employed to examine the hormonal balance of progesterone and estrogen — and especially, to determine the condition referred to as estrogen dominance.
The theory of estrogen dominance was formulated by Dr. John Lee, MD, in his book Natural Progesterone – The Multiple Roles of a Remarkable Hormone, published in 1993. There, he discussed the role of progesterone in balancing the action of estrogen in the body. And most importantly, Dr. Lee pointed out that women can suffer from estrogen dominance even though they have normal or low levels of estrogen because there might not be enough progesterone to balance it.
This ratio was created for such a purpose as to make this imbalance visible.
A Helpful Tool, With Caveats
Pg/E2 ratio is very valuable in the clinical setting, but its scientific background does have certain shortcomings that should be mentioned. First of all, most scientific papers devoted to this topic focus on the value of Pg/E2 in the prediction of the success rate before IVF treatments; yet, even in this particular area, research data remains controversial. Although in some studies a higher estrogen to progesterone ratio in the early luteal phase proves to predict better results in IVF, there is still no scientific consensus.
Nevertheless, many doctors practicing functional medicine find the Pg/E2 ratio an interesting and practical clinical approach despite the lack of consensus in scientific literature.
How the Pg/E2 Ratio Works
The significance of the ratio of Pg to E2 is in its ability to identify relatively imbalanced levels of hormones that would normally be considered normal when evaluated separately.
Let us take the following case as an example: the levels of both estradiol and progesterone are within the standard reference range. Thus, from the outside, they would seem to be okay. However, if estradiol happens to be at the upper limit of its normal range and progesterone is at the lower limit, it is likely to create a ratio that will show some sort of imbalance between the two hormones, where estrogen is dominant compared to progesterone.
A low Pg/E2 ratio means high estrogen compared to progesterone – the clinical condition known as estrogen dominance. High Pg/E2 ratio means high progesterone compared to estrogen – the state known as progesterone dominance, which is also associated with its own symptoms.
Estradiol is being used for this test instead of other estrogens (estrone and estriol) because it is the strongest of all three.
Signs and Symptoms of Estrogen Dominance
This condition is characterized by high estrogen levels relative to progesterone, which does not always mean an increase in estrogen, but rather the deficiency of progesterone to offset it. The following symptoms develop due to the unopposed estrogen:
- Heavy or prolonged menstrual bleeding
- Breast tenderness and swelling
- Uterine fibroids
- Fatigue and low energy
- Brain fog
- Mood swings and anxiety
- Bloating and water retention
- Unexplained weight gain
- Headaches or migraines
The diagnosis of estrogen dominance is made in the luteal phase of the menstrual cycle, which is the second part of the cycle when the level of progesterone is the highest. High estrogen in the ovulatory phase may cause symptoms, too.
Factors that can contribute to estrogen dominance include:
- Chronic stress (elevates cortisol, which suppresses progesterone)
- Insulin resistance and obesity
- Inflammation
- Poor gut health and dysbiosis (the gut microbiome plays a direct role in estrogen clearance through a network of bacteria called the estrobolome)
- Diet and alcohol consumption
- Estrogen detoxification imbalances in the liver
- Environmental estrogen exposures from xenoestrogens – endocrine-disrupting chemicals found in plastics, pesticides, and common personal care
- products containing parabens and phthalates
- Perimenopause and puberty
Signs and Symptoms of Progesterone Dominance
While estrogen dominance is a much-discussed imbalance, the opposite condition, progesterone dominance, is equally important to know about. Progesterone at high levels in women of reproductive age is not uncommon and does not create problems. However, some women who take additional progesterone or pregnenolone experience certain symptoms due to high levels of progesterone, which are quite similar to those seen in the case of estrogen dominance:
- Fatigue
- Increased appetite
- Bloating and constipation
- Breast tenderness
- Irregular bleeding patterns
- Low libido
- Irritability
- Premenstrual dysphoric disorder (PMDD)
Factors that may contribute to progesterone dominance include: progesterone or pregnenolone supplementation, pregnancy, low luteal estrogen levels, ovarian cysts, and congenital adrenal hyperplasia.
What the Pg/E2 Ratio Doesn’t Capture
The Pg/E2 ratio is an excellent starting point, but it has a number of limitations that must be taken into consideration. The ratio takes into account just two hormones of the complicated interplay between estrogen and progesterone. Moreover, other players in this process lead to the manifestation of estrogen dominance symptoms and are not taken into account in the Pg/E2 ratio.
Estrogen metabolites are one of such factors. The 16-hydroxyestrone (16-OHE1) is a metabolite of estrogen that is very strong in binding to estrogen receptors, leading to tissue proliferation, and is linked to heavy menstrual bleeding, breast tenderness, and fibroid formation. Such classic symptoms of estrogen dominance can be present in a patient even with a balanced Pg/E2 ratio due to this metabolite. Without testing for estrogen metabolism separately, this factor will remain undetected.
Another type of hormone-mimicking substances, which can lead to the disruption of hormonal balance without showing up in a hormone test, is xenoestrogens – the environmental endocrine disruptors. They include plastics, pesticides, and industrial and personal care products’ components such as parabens and phthalates.
When to Measure the Pg/E2 Ratio
This assessment requires proper timing. The analysis of the Pg/E2 ratio should take place when it is believed that the level of progesterone is at its peak, which normally happens 5 to 7 days after ovulation. It means that on average 28-day cycle, such an analysis should take place on days 19 to 22.
As for follicular and ovulatory phases, it is normal that progesterone levels are low there as the hormone is primarily synthesized by the adrenal glands. Estrogen is the main hormone in these two phases, and this is absolutely normal. As for such phases, it is not possible to conduct any analysis related to progesterone as the results would be completely misleading.
How the DUTCH Test Evaluates Progesterone-Estrogen Balance
DUTCH test gives a more holistic look at both the progesterone and estrogen hormone profile than just the Pg/E2 ratio test can provide.
It measures all three estrogen hormones, such as E1, E2, and E3, together with progesterone metabolites, including the serum equivalent of progesterone. But the biggest advantage of this test is that it examines estrogen metabolism by analyzing the 2-OH, 4-OH, and 16-OH estrogen pathways – an important aspect that the Pg/E2 ratio does not account for.
For those women who suffer from some symptoms, indicating their hormonal imbalance but have no abnormal lab results on standard tests, the DUTCH test is the one that may reveal underlying issues and give a proper diagnosis. Furthermore, for those with irregular menstrual cycles, when a single-day test cannot show an overall picture, there is the DUTCH Cycle Mapping test, allowing to track the whole process of hormonal production and balance over the course of the menstrual cycle.
If you suffer from hormonal imbalance, especially estrogen dominance, and need to learn more about it, you can visit dutchtesting.org to book a free consultation and see whether the DUTCH test would be the most appropriate next step.
Frequently Asked Questions (FAQs)
1. What is the Pg/E2 ratio, and what does it measure?
Pg/E2 Ratio is the progesterone/estrogen ratio, a method that is applied in assessing the balance between these two hormones. This ratio is very useful in determining the dominant hormone since it allows one to determine if there is either estrogen dominance or progesterone dominance, regardless of the levels being within the reference range.
2. What is estrogen dominance?
Estrogen dominance is a condition that involves the dominance of estrogen over progesterone. The dominance does not necessarily mean a high level of estrogen, but it simply means that the progesterone is low enough for estrogen dominance to occur. Its common symptoms include heavy menstruation, breast soreness, irritability, tiredness, fluid retention, and weight gain.
3. Can you have estrogen dominance with normal estrogen levels?
Yes, it is possible because dominance is determined based on the ratio of estrogen and progesterone rather than the absolute estrogen levels.
4. When should the Pg/E2 ratio be measured?
It is important to assess the ratio when you are halfway through the luteal phase, on about days 19 to 22 in your menstrual cycle, assuming it lasts 28 days, because it is at this time that your progesterone level would naturally reach its highest point. The ratio may provide erroneous information when it is tested outside the luteal phase, especially in the follicular phase when progesterone level is naturally low.
5. What are the limitations of the Pg/E2 ratio?
The Pg/E2 ratio considers progesterone and estradiol levels and not estrogen metabolites such as 16-hydroxyestrone, which can cause estrogen dominance, and also does not consider xenoestrogens, which are environmental estrogens.
6. What is progesterone dominance, and is it common?
Progesterone dominance refers to an uncommon type of hormonal imbalance in which the body has higher levels of progesterone in relation to estrogen levels. The symptoms associated with this condition include fatigue, bloating, breast tenderness, lack of libido, and menstrual abnormalities. Progesterone dominance is usually found in women on progesterone supplements, pregnant, and those with ovarian cysts.
7. How does the DUTCH test assess progesterone-estrogen balance?
DUTCH testing includes testing of all three estrogens, progesterone metabolites, as well as a serum equivalent and a thorough evaluation of estrogen metabolism, including 16-OH estrogen. It gives a more comprehensive assessment of hormonal balance than just the Pg/E2 ratio because it assesses not only the balance of hormones but also their metabolism and clearance.
