The Ovarian, Adrenals, and Thyroid (OAT) Axis plays a central role in women’s hormone health. When these three systems work in harmony, they regulate menstrual health, metabolism, fertility, mood, energy, and overall well-being. Disruption in any part of the OAT axis can lead to hormone imbalances and symptoms such as irregular periods, weight gain, or fatigue. In this article, we will talk about the OAT Axis in more detail, starting with the ovaries.
The Role of the Ovaries in Women’s Hormone Health
The ovaries form part of the female reproductive system and has two roles:
They produce our female hormones (estrogen and progesterone).
They house the egg cells which get released during ovulation.
Hormone Fluctuations During the Menstrual Cycle
During the follicular phase of the menstrual cycle, estrogen is the predominant acting hormone playing a role in thickening of the uterine lining to prepare for a potential pregnancy.
During the luteal phase of the menstrual cycle, progesterone is the predominant acting hormone playing a role in maintaining the thickness of the uterine lining for a potential pregnancy.
Estrogen Dominance: A Common Hormonal Imbalance
One of the most common hormonal imbalances seen in women is estrogen dominance. This term can be misleading as it alludes to estrogen being high, but this is not always the case.
What is Estrogen Dominance?
It occurs when there is too much estrogen, relative to progesterone.
This hormone imbalance can make estrogen “stronger.” In some cases, it is because there is insufficient progesterone to counteract the effects of estrogen.
Symptoms may include: premenstrual mood swings, irritability, depression, bloating, acne, breast tenderness, and food cravings.
Understanding estrogen dominance is crucial for addressing hormonal health issues as it ties directly into the balance of the OAT Axis.
The Ovaries and the OAT Axis
The ovaries affect the OAT axis by:
Regulating the balance of estrogen and progesterone.
Influencing adrenal hormone production through shared precursors like DHEA.
Modulating thyroid hormone activity via estrogen and progesterone levels.
In short, healthy ovarian function is essential for a balanced OAT axis, and any ovarian dysfunction can ripple through the adrenals and thyroid, affecting energy, metabolism, stress resilience, and overall hormonal health.
In this video, we will go over the functions of the ovaries and its relationship to the thyroid and the adrenals in terms of women’s hormone health.
Understanding the Role of the Adrenal Glands
The adrenal glands sit on top of the kidneys and they are essential for stress management, metabolism, energy regulation, and hormone balance in women.
One of their most important functions is the production of cortisol, commonly known as the “fight or flight hormone.” Cortisol helps the body respond to both acute and chronic stress.
How Cortisol Works
During acute stress, our body produces cortisol in response to the stress in front of us (e.g. a bear). The rise in cortisol helps us:
Become more alert and aware.
Increase our heart rate and circulation increases.
Boosts metabolism to generate energy for immediate action (e.g. fight or run away from the bear).
Once the stressor is gone, cortisol levels should return to baseline, allowing the body to recover.
In modern life, chronic stress is common due to our fast pace lifestyle. Cortisol levels do not return to baseline and remain elevated. If left untreated, this can eventually lead to cortisol deficiencies (adrenal fatigue).
To summarize cortisol:
Low cortisol: Limited capacity to access energy stores and deal with stress leading to fatigue and poor stress response.
High cortisol: Chronic overdrive, increased inflammation, and potential for disruption of other hormones.
This imbalance can directly affect how we cope with stress and women’s hormone health, including menstrual health, fertility, and mood.
The Adrenals and the OAT Axis
The adrenal glands do not work in isolation. They are part of the OAT Axis, a critical network that regulates hormonal balance in women.
Ovaries: Produce estrogen and progesterone; rely on adrenal support for hormone precursors (e.g. DHEA)
Thyroid: Regulates metabolism; cortisol imbalances can interfere with metabolism and thyroid hormone production
In this video below, I will go over the functions of the adrenal glads and its relationship to the ovaries and thyroid in terms of women’s hormone health.
Understanding the Thyroid
The thyroid gland is a small, butterfly-shaped gland that sits at the base of the neck. Despite its size, it plays a powerful role in regulating many essential bodily functions, including metabolism, heart rate, muscle function, digestion, and cell regeneration.
Because thyroid hormones influence so many bodily processes, thyroid imbalance often mimics other health conditions. That’s why assessing thyroid function is critical in any comprehensive health evaluation, no matter what the concern is.
WHAT IS TSH AND WHY IT MATTERS
Thyroid-Stimulating Hormone (TSH) is produced by the pituitary gland. It is the primary hormone used to screen for thyroid dysfunction.
In conventional or allopathic medicine, TSH is often tested alone. It is used as a screening tool, meaning that if it is within the normal reference range then other tests may not be needed.
However, relying solely on TSH can be misleading. Most labs define the normal TSH reference range as 0.35–4.00 mIU/mL, but research suggests that the optimal range may be narrower — often between 1.0–2.5 mIU/mL.
This means that many women with symptoms of thyroid dysfunction, such as fatigue, hair loss, weight changes, or brain fog may still be told their results are “normal.”
Understanding thyroid hormones and What is reverse T3?
The thyroid produces the following hormones:
T3 is an active thyroid hormone and is used for metabolism.
T4 is an inactive thyroid hormone and gets converted into T3 as needed.
Reverse T3 (rT3) is a byproduct of T4 hormone conversion. Instead of converting T4 into T3, the body sometimes converts it into rT3, especially during stress, inflammation, or chronic illness. rT3 can block the effects of active thyroid hormones.
Unfortunately, reverse T3 testing is not routinely included in conventional thyroid panels, which means this imbalance can easily go unnoticed.
In addition, conventional thyroid replacement medications are usually in the form of T4. If there is a conversion issue, simply giving T4 alone may not help. Therefore, testing TSH alone when on thyroid medication is not always sufficient.
The Importance of Thyroid Antibodies
Thyroid peroxidase (TPO) and thyroglobulin antibodies (TgAb) are two key thyroid antibodies. Elevations in these antibodies can indicate autoimmune thyroid conditions such as Hashimoto’s disease. These thyroid antibodies can also be elevated even if TSH is normal.
How Low Stomach Acid Affects Thyroid Function
Low stomach acid (hypochlorhydria) can contribute to poor thyroid function. Stomach acid not only breaks down food but also activates digestive enzymes like pepsinogen and intrinsic factor, which are essential for protein digestion and vitamin B12 absorption.
When digestion is impaired, your body may struggle to absorb key nutrients like iodine, selenium, zinc, and iron, all of which are crucial for thyroid hormone production and conversion.
Thyroid and The OAT AXIS in Women’s Health
In this video, we’ll explore how the thyroid gland interacts with the ovaries and adrenal glands, and how this hormonal connection influences women’s hormone health, energy, and fertility.
The OAT Axis
So what does this all mean and how are the ovaries, adrenals, and thyroid gland connected to one another?
The Female Hormone Pathway below illustrates the intricacies of the female hormone pathway and how the hormones are connected to one another.
Where Does Cortisol Come From?
To the left of the Female Hormone Pathway, we can see that our stress hormone cortisol (made in the adrenals) comes from progesterone (made in the ovaries).
With everyday stress, whether mental, physical, or emotional, or simply being busy, and having a lot on our plate, we are constantly stealing from our female hormone progesterone in order for our body to produce cortisol to help us deal and cope with ongoing stress.
This is how many women appear to be estrogen dominant, simply not having enough progesterone to combat estrogen due to stress.
Female Hormone Pathway: Gupta, M. K., & Chia, S. Y. (2013). Ovarian hormones: structure, biosynthesis, function, mechanism of action, and laboratory diagnosis. In Clinical Reproductive Medicine and Surgery (pp. 1-30). Springer, New York, NY.
The connection between Androgen Precursors and Female Hormones
To the right of the of the Female Hormone Pathway, we can see that androstenedione and testosterone (which are androgens or male hormones) comes from DHEA, while estrogen (estradiol) comes from testosterone.
This shows how important it is to do an all inclusive blood work to see where the issue lies and just because one test is normal does not mean that the other ones will be.
The Connection Between the Ovaries and the Thyroid
The literature also suggests that estrogen dominance may also increase TBG (thyroid binding globulin), a protein produced in the liver that binds to thyroid hormones, making them inactive thus interfering with thyroid hormone function.
The Connection Between the Ovaries and the Adrenals
On top of this, estrogen dominance may also increase cortisol binding globulin (CBG), which is also a protein that is produced in the liver.3 CBG binds to cortisol and also has the capacity to bind to progesterone.4
Cortisol that is bound to CBG cannot be used by the body and the adrenal glands will have to try to make more cortisol in an attempt to accommodate, thus stealing more from progesterone. This becomes a vicious cycle in which we do not have enough progesterone to counteract the effects of estrogen.
To Summarize the OAT Axis in Women’s Health
Because of the connections between the ovaries, the adrenals, and the thyroid gland, women tend to experience overlapping signs and symptoms:
Estrogen dominance: irregular periods, menstrual cramps, bloating, breast tenderness, migraines, brain fog, hair loss, insomnia, low libido, clotting, mood swings
Chronic stress: irregular or missed periods, irritability, fatigue, headaches, hair loss, weight gain, digestive complains
Under functioning thyroid (hypothyroidism): low energy, fatigue, digestive complaints (e.g. constipation), hair loss, menstrual changes, brain fog, cold intolerances, weak nails
OAT Axis Support in Etobicoke and Surrounding Toronto: Naturopathic Care for Women’s Hormone Health
If you are experiencing symptoms such as irregular periods, PMS, acne, fatigue, weight changes, or mood imbalances, it may be a sign of dysfunction within the OAT (Ovarian–Adrenal–Thyroid) Axis. At Naturopath in Etobicoke, we take an integrative and personalized approach to assessing and supporting hormone health at the root cause.
Our naturopathic care focuses on:
Comprehensive hormone assessment including menstrual history, stress patterns, and metabolic health
Targeted lab testing (when appropriate) to evaluate thyroid function, adrenal health, and hormone balance
Individualized treatment plans using clinical nutrition, lifestyle medicine, and evidence-informed supplementation
Support for common concerns such as estrogen dominance, PCOS, PMS, infertility, and burnout
By addressing the connection between the ovaries, adrenals, and thyroid, we aim to restore balance across the entire OAT axis—helping improve energy, regulate cycles, stabilize mood, and optimize overall well-being.