When we think about endometriosis, we often focus on the reproductive system and hormones. But increasingly, researchers are exploring another important area: the gut.
The gut microbiome, immune system, intestinal barrier and hormone metabolism are all interconnected. While a stool test cannot diagnose endometriosis, functional stool testing may provide useful information about aspects of digestive and immune health that can be considered as part of a broader, personalised approach.
So, what exactly can a stool test reveal—and why might it be relevant when endometriosis is part of the picture?
The Gut–Hormone Connection
Your gut is far more than a digestive organ.
The trillions of microorganisms living in the digestive tract—collectively known as the gut microbiome—are involved in a wide range of processes throughout the body.
These include:
- Oestrogen metabolism
- Immune regulation
- Inflammatory processes
- The gut–brain axis
- Intestinal barrier function
All of these areas are increasingly being explored in relation to endometriosis.
Endometriosis is a complex condition, and there is no single explanation for why it develops or behaves differently from person to person. However, understanding what is happening beyond the reproductive system can sometimes help us build a more complete picture of an individual’s health.
Could Your Gut Influence Oestrogen Metabolism?
One particularly interesting area of research is the relationship between the gut microbiome and oestrogen.
Certain gut bacteria produce an enzyme called beta-glucuronidase (β-glucuronidase). This enzyme is involved in the processing of oestrogen within the gut.
After the liver processes hormones for elimination, some oestrogen metabolites are transported into the digestive tract. Gut microbial activity may influence whether some of these compounds are reactivated and potentially reabsorbed into circulation.
The collection of gut bacteria and genes involved in oestrogen metabolism is often referred to as the estrobolome.
Some comprehensive stool tests can assess β-glucuronidase activity, providing one potential piece of information about microbial activity associated with hormone metabolism.
However, it is important to be clear: a stool test cannot tell us your total oestrogen levels or diagnose an oestrogen-related condition. Results need to be interpreted in the context of symptoms, medical history, menstrual health and, where appropriate, conventional medical testing.
What Is Living in Your Gut?
The composition of the gut microbiome is another area that may be explored through comprehensive stool testing.
Depending on the test used, markers may include levels or relative abundance of important bacterial groups and beneficial microbes, such as:
- Lactobacillus
- Bifidobacterium
- Faecalibacterium
- Roseburia
- Akkermansia
Research has identified differences in the gut microbiome of people with endometriosis compared with those without the condition. However, this is an evolving area of science.
At present, there is no single “endometriosis microbiome” that can be identified through a stool test.
Instead, I look at microbiome findings as part of a much wider clinical picture. Factors such as diet, medication, stress, bowel habits, previous antibiotic use and digestive symptoms can all influence the microbiome.
Gut Immunity and Endometriosis
The immune system plays an important role in endometriosis research, which makes gut immune markers particularly interesting.
One marker sometimes included in comprehensive stool testing is secretory IgA (sIgA).
Secretory IgA is an antibody found on mucosal surfaces, including the digestive tract. It plays an important role in the interaction between the immune system and the microorganisms living within the gut.
Changes in gut barrier function and immune activity are areas of ongoing research in endometriosis and other inflammatory conditions.
Again, an individual stool marker cannot explain or diagnose endometriosis. But assessing gut immune activity may sometimes provide useful context, particularly for someone experiencing ongoing digestive symptoms alongside their endometriosis.
What About the Gut Barrier?
The intestinal barrier is designed to allow nutrients to pass into the body while helping to maintain an appropriate boundary between the contents of the gut and the rest of the body.
Several factors can influence gut barrier health, including the microbiome and the production of beneficial compounds such as short-chain fatty acids.
Akkermansia
Akkermansia is a bacterium that is often studied for its relationship with the intestinal mucus layer.
The mucus layer forms an important part of the gut’s protective environment, and changes in Akkermansia abundance are being investigated in a variety of health conditions.
Butyrate
Butyrate is a short-chain fatty acid produced when certain gut bacteria ferment dietary fibre.
It is an important energy source for cells lining the colon and is involved in maintaining normal intestinal function and immune responses.
Some functional stool tests can provide information relating to short-chain fatty acid production, including butyrate.
When considering these results, I am interested not simply in whether a number is “good” or “bad,” but in how the result fits alongside the person’s symptoms, diet, bowel function and overall health picture.
Is There Inflammation in the Gut?
For some people with endometriosis, digestive symptoms such as bloating, altered bowel habits and abdominal discomfort can overlap with other gastrointestinal conditions.
This is one reason it is important not to assume that every digestive symptom is caused by endometriosis.
Comprehensive stool testing may include markers such as:
Calprotectin
A marker that can be associated with intestinal inflammation and may warrant further medical investigation depending on the result and clinical context.
Eosinophil Protein X (EPX)
A marker related to eosinophilic activity within the gastrointestinal tract.
Secretory IgA (sIgA)
A marker that can provide information about aspects of mucosal immune activity.
These markers should always be interpreted carefully. Abnormal inflammatory markers may require referral to a GP or gastroenterologist for appropriate medical investigation.
Functional testing should complement—not replace—medical care.
Looking at the Bigger Picture
I don’t see a stool test as a way to “find the cause” of endometriosis.
Endometriosis is complex. It involves multiple biological systems, and every person’s experience can be different.
Instead, comprehensive testing may help us explore questions such as:
- Are there signs of digestive inflammation that need further investigation?
- What does the overall microbiome profile look like?
- Are there clues relating to microbial diversity and beneficial bacteria?
- How is the gut immune environment functioning?
- Are there markers that may be relevant to intestinal barrier health?
- What might we learn about microbial activity involved in hormone metabolism?
The answers to these questions may help inform a more personalised strategy around nutrition, digestive health and lifestyle support.
Can a Stool Test Diagnose Endometriosis?
No.
A stool test cannot diagnose endometriosis.
Endometriosis should be assessed and diagnosed through appropriate medical care and specialist evaluation. Depending on the individual situation, this may involve clinical assessment, imaging and, in some cases, surgery.
Stool testing is not a replacement for gynaecological care.
What it can potentially offer is additional information about the gut environment, particularly when digestive symptoms, immune health or broader hormonal questions are also part of the clinical picture.
Why I Look Beyond Hormones
When supporting someone with endometriosis, I believe it is important to look at the whole person.
Hormones matter—but so can:
- Gut health
- Digestion and bowel function
- Inflammation
- Immune activity
- Nutrition
- Stress and the nervous system
- Sleep
- Individual symptoms and medical history
The body doesn’t operate in isolated systems.
Sometimes, understanding your hormonal health means looking beyond your hormones.
Could Comprehensive Stool Testing Be Right for You?
If you are living with endometriosis and also experiencing persistent digestive symptoms, bloating, bowel changes or concerns about your gut health, a comprehensive stool assessment may be something to discuss as part of a wider, individualised approach.
The most important part is not simply ordering a test—it’s understanding whether testing is appropriate, how the results should be interpreted and when further medical investigation is needed.
Every person’s situation is different, and testing should always be considered within the context of your symptoms and wider health history.
If you’d like to explore whether a comprehensive gut health assessment may be appropriate for you, you can book a complimentary 15-minute discovery call to discuss your options.
