Thyroid and PMOS: The Connection No One Is Talking About
PMOS (formerly PCOS) and thyroid disease are not coincidental roommates. They share the same upstream biochemistry. And I learned that the hard way, in my own body, before there was even a name for it.
Last week, conventional medicine finally renamed PCOS. It is PMOS now. Polyendocrine Metabolic Ovarian Syndrome. And the new name explicitly recognizes what functional medicine has been working with for over a decade: this is a whole-body, endocrine and metabolic condition with root causes that include nutrient deficiencies, stress, blood sugar dysregulation, gut health imbalances, and more.
Here is the part that gets glossed over in the news coverage. PMOS and thyroid disease are deeply, biochemically connected. If you have one, your risk of having the other is significantly elevated. And if you have both, treating them in isolation almost never works.
Before I get into the biochemistry, I want to share why this conversation matters so much to me. Because I lived a version of it.
My Story (Why I’m Writing This)
Y’all. Let me take you back to my early 20s for a minute.
I was a clinical dietitian working in long-term acute care. Master’s in nutritional sciences. Training for a half-marathon. Working out twice a day. Keeping my calories low because that’s what I was taught in school. The equation was simple: calories in, calories out. The body would do what the math told it to do. (Spoiler. It would not.)
I was also exhausted in a way I didn’t have language for. I’m talking couldn’t-function exhausted. I had acne I couldn’t get rid of. Bloating. Daily migraines for a month straight. My periods were a mess. My weight wouldn’t budge no matter how hard I worked it.
And the thing that quietly haunted me the whole time? I was the one supposed to have the answers. I was the dietitian.
By a stroke of luck (or the universe, or whatever you want to call it), I ended up in front of an OB/gyn who I didn’t know at the time also studied functional medicine. I didn’t even know what that meant. She ran labs I’d never had run before, looked at me, and said something I’ll never forget:
In 2012. This was UNHEARD of. Nobody was saying that. The framework didn’t exist yet. She was looking at me through a lens that wouldn’t be formally recognized for another decade-plus.
I drank the functional medicine kool-aid that day and never looked back.
Because here’s what I realized. The very advice I was trained to give my patients (eat less, move more, your calories are too high) was making my own body worse. My adaptive metabolism was slowing down to conserve resources because I was under-fueling and over-exerting. My hormones were responding accordingly. My weight, my periods, my migraines, my acne. All of it was downstream of a body trying to protect me from what I was doing to it.
Our bodies are so much more complex than calories in, calories out. And I had to live it to understand it.
Fast forward almost 15 years. Conventional medicine just renamed PCOS to acknowledge what that OB/gyn told me in 2012 and what we’ve been working with at Chews Food Wisely ever since: this is a whole-body, endocrine and metabolic condition. As my favorite saying goes: to tame it, you have to name it.
Being categorized accurately is going to validate so many more women and get them the care they actually need. That’s why I’m writing this. So let’s get into the science.
What Changed When PCOS Became PMOS
The 2026 rename, led by The Lancet through a global consensus process, did not change how the condition is diagnosed. What it changed is the framework.
The old name (Polycystic Ovary Syndrome) centered the ovaries and made it sound like a single-organ, reproductive issue. The new name (Polyendocrine Metabolic Ovarian Syndrome) centers what functional medicine has been seeing in clinical practice for years: this is a multi-system endocrine and metabolic condition that happens to also affect the ovaries.
The implications are significant. The new framework opens the door to formally recognizing subtypes. It validates the work that has been happening around insulin, inflammation, the thyroid, and the HPA axis as central, not peripheral. And it (hopefully) closes the diagnostic gap for the estimated 70% of affected women who have never been diagnosed because they didn’t fit the narrow “cyst” picture.
Globally, this condition affects an estimated 170 million women. Most of them do not know it. Which means a lot of symptoms that have been written off as “normal” are about to start belonging to a recognized story.
The 2.4x Risk Link Between Hashimoto’s and PMOS
Here is the headline statistic that drives this entire conversation:
25% of women with PMOS have Hashimoto’s. 43% have subclinical hypothyroidism. And if you have Hashimoto’s, you are 2.4 times more likely to also have PMOS than the general population.
These two conditions are not coincidentally hanging out in the same body. They are feeding each other biochemically through shared root drivers. Let’s unpack how.
How Thyroid and PMOS Feed Each Other Biochemically
The connection between thyroid dysfunction and PMOS is bidirectional. Each condition makes the other worse. Here is the loop:
The Feedback Loop
PMOS → worsens thyroid: high insulin and chronic inflammation suppress T4-to-T3 conversion, raise reverse T3, and drive immune cells toward TPO antibody activity.
Hypothyroid → worsens PMOS: a sluggish thyroid lowers SHBG (mimicking the PMOS androgen picture), slows insulin clearance (worsening insulin resistance), and impairs estrogen clearance through the liver.
This is why a woman with PMOS who is told her thyroid labs are “normal” often still has thyroid symptoms. And it is why a woman with Hashimoto’s who is told her hormones are “fine” often still has PMOS-pattern symptoms. The two systems are wired together, and the conventional model rarely tests for the full picture.
Insulin: The Upstream PMOS Driver
In roughly 75% of women with PMOS, chronically elevated insulin is the upstream driver. Not just elevated. It is actively whispering directives to multiple organs at once. Here is exactly what insulin does in PMOS:
At the ovary: Insulin signals the theca cells (the testosterone factories) to upregulate an enzyme called CYP17. Specifically, the 17,20-lyase activity. Translation: more testosterone, more DHEA, more androstenedione. All the androgens that drive acne, hair thinning, and unwanted facial hair growth.
At the liver: Insulin suppresses SHBG (sex hormone binding globulin) production. SHBG is the protein that keeps testosterone in check. Less SHBG means more free testosterone bioavailable to cause symptoms.
At the pituitary: Insulin disrupts the LH/FSH ratio (more LH, less FSH), which scrambles the ovulation signal. Hence the irregular, heavy, or missing periods.
Inflammation also drives androgens, even without insulin in the picture. Pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) directly stimulate theca cells via the same CYP17 pathway. This is why some lean women with PMOS still have hyperandrogenism. Their driver is inflammation-dominant rather than insulin-dominant. Which brings us to the thyroid side.
Where Thyroid Biochemistry Overlaps With PMOS
Your thyroid makes mostly T4 (the inactive form of thyroid hormone). To use it, your body converts T4 into T3 (the active form). That conversion happens in your liver, gut, kidneys, and peripheral tissues. It requires a specific cast of nutrient cofactors and a calm hormonal environment.
Here is where PMOS biochemistry breaks the thyroid system:
Selenium-dependent deiodinases are the enzymes that convert T4 to T3. They need selenium and a low-inflammation environment to function. PMOS provides neither.
Chronically high cortisol (which many PMOS women run on, often from under-eating, over-exercising, and chronic stress) downregulates deiodinase activity and shunts T4 into reverse T3. Reverse T3 is an inactive metabolite that occupies T3 receptors without actually doing anything. You get hypothyroid symptoms with a “normal” TSH.
Inflammation drives TPO antibody activity in Hashimoto’s. The same cytokines that disrupt theca cells (TNF-α, IL-6) also drive immune attack on thyroid tissue.
This is why I lose patience with the “your TSH is normal, you’re fine” conversation. TSH alone does not tell you whether your cells are actually receiving and using active T3. A comprehensive thyroid evaluation needs to include free T3, free T4, reverse T3, and TPO + Tg antibodies. If we’re not looking at all of it, we’re not looking.
The HPA-OT Axis Explained
The HPA-OT axis stands for hypothalamic-pituitary-adrenal-ovarian-thyroid axis. It is a fancy way of saying your brain, your adrenals, your ovaries, and your thyroid are all on the same group chat. When one of these systems is stressed, dysregulated, or inflamed, the entire thread lights up.
Specifically, when cortisol stays elevated (whether from chronic stress, under-eating, over-exercising, or under-sleeping. Ahem, me at 23), here is what happens in sequence:
Step 1. Cortisol rises. It suppresses TSH at the pituitary, slowing thyroid hormone output.
Step 2. Cortisol downregulates deiodinase, slowing T4-to-T3 conversion and increasing reverse T3.
Step 3. Cortisol is a glucocorticoid. Its job is to tell your body to release stored glucose from your muscles and liver to fuel a perceived emergency. So your blood sugar can rise sharply even when you haven’t eaten anything. It is purely the stress response doing what it was designed to do.
Step 4. Chronically elevated glucose leads to chronically elevated insulin. Your pancreas keeps releasing more insulin to clear the glucose, but the cells stop responding well to it (because there is so much of it circulating). This is the start of insulin resistance.
Step 5. Now you are stuck in a cycle: high cortisol → high blood sugar → high insulin → insulin resistance → ovaries get the signal to produce more testosterone → blood sugar swings → more cortisol. The wheel keeps turning.
Step 6. Cortisol also drives long-term inflammation. That inflammation drives both theca cell androgen production AND TPO antibody activity in Hashimoto’s.
One stressed system. A self-perpetuating cycle of high cortisol, high blood sugar, high insulin, elevated testosterone, and chronic inflammation. Every single one of these shows up in both PMOS and thyroid dysfunction.
Why Gut Health Is The Most Underrated Root
Gut dysfunction is the most underrated driver of both PMOS and thyroid disease. It touches every other system we have discussed. Here are the five major mechanisms:
1. Nutrient absorption. Your gut is where you absorb the nutrients your hormones need. Selenium for thyroid conversion. Iron for thyroid hormone synthesis. Zinc and magnesium for insulin signaling. B vitamins for methylation. Vitamin D status. If your gut is not working, you can eat the right foods and still end up deficient.
2. The estrobolome. A specific subset of gut bacteria produces an enzyme called β-glucuronidase that recycles or eliminates estrogens. When the microbiome is dysbiotic, estrogens get reabsorbed instead of cleared. The result is estrogen dominance, which compounds PMOS symptoms and impacts thyroid signaling.
3. Intestinal permeability (“leaky gut”). When the gut barrier is compromised, bacterial endotoxins (LPS) cross into circulation and activate the same cytokines that drive theca cell androgen production AND TPO antibody activity. The systemic inflammation behind both conditions often starts in the gut.
4. Gut microbial T4 to T3 conversion. Approximately 20% of T4-to-T3 conversion happens via gut microbes. Dysbiosis means less T3 even when TSH looks “normal.”
5. The gut-immune axis. Roughly 70% of your immune system lives in gut-associated lymphoid tissue. When the gut is leaky and dysbiotic, the immune system becomes reactive. A reactive immune system is the one that starts producing TPO antibodies against thyroid tissue.
This is why working on the gut is foundational for both PMOS and Hashimoto’s. It is not a side mission. It is the terrain everything else depends on.
The Nutrients That Pull Double Duty for Thyroid and PMOS
Because PMOS and thyroid disease share root drivers, they respond to the same handful of nutrient cofactors. When these run low, every other driver gets worse.
Selenium
Required for deiodinase enzymes (T4 to T3 conversion) and glutathione peroxidase (your body’s main antioxidant defense against oxidative thyroid damage). Brazil nuts, sardines, and eggs are concentrated sources.
Myo-inositol + D-chiro-inositol (40:1 ratio)
Second messengers in insulin signaling. Myo-inositol specifically improves FSH signaling at the ovary. The 40:1 ratio is the evidence-based blend used for PMOS support.
Vitamin D
Modulates immune function (lowers TPO antibody activity in Hashimoto’s) and improves insulin sensitivity. A foundational nutrient that the majority of women are deficient in. (Mine at 23? Severe.)
Zinc
Required for thyroid hormone synthesis, immune regulation, and androgen receptor modulation. It pulls clinical weight on both sides of the equation.
Magnesium
Cofactor for over 300 enzymatic reactions, including insulin receptor function and HPA axis regulation. The “calm down” mineral for both stressed systems.
Omega-3 fatty acids (EPA + DHA)
Anti-inflammatory at the cell membrane level. Lowers TPO antibodies, supports insulin signaling, and reduces androgen-driven inflammation.
Nutrient repletion is part of the actual therapy for both conditions. It is not a wellness add-on. It is the cofactor base that makes the rest of the biochemistry possible.
A Root-Cause Framework: The BRAIN Method
At Chews Food Wisely, we organize all of this around The BRAIN Method: Blood Sugar Balance, Regulating Inflammation, Adrenal Resiliency, Intestinal Health, and Nutrient Repletion. Five pillars, in this order, because the order matters.
Each pillar maps directly onto a root driver of both PMOS and thyroid disease. We are not chasing symptoms. We are addressing the upstream wiring. Because if you handle the wiring, the downstream symptoms tend to follow.
It is exactly the approach that pulled me out of where I was at 23. And it is the approach we have now used with over 1,000 women.
For a deeper dive into each pillar, you can read our full BRAIN Method overview here.
Ready For Personalized Support?
Apply to work with us 1:1.
If you have thyroid dysfunction, PMOS, or both, our 1:1 coaching is built around the exact framework outlined in this post. Comprehensive testing, personalized protocols, and ongoing support from a functional dietitian.
Apply NowSo What Now?
If you are sitting here reading this thinking “oh. OH.” Two things to know:
First: You weren’t crazy. The symptoms you have been told are “normal” or “unrelated” probably are not. The biochemistry finally lets them belong to one story. (I lived that. I know.)
Second: This is fixable. Not always overnight, not always in a linear way, but the root drivers respond beautifully to consistent, personalized support. At Chews Food Wisely, we have used this exact approach with over 1,000 women.
If you suspect you have thyroid dysfunction, PMOS, or both, the next step is comprehensive testing paired with a functional approach that addresses all the root drivers we just walked through. That is exactly what we do.
Frequently Asked Questions
What is PMOS and is it the same as PCOS?
PMOS (Polyendocrine Metabolic Ovarian Syndrome) is the new name for what was previously called PCOS (Polycystic Ovary Syndrome). The 2026 renaming, led by The Lancet, reflects the recognition that this condition is a whole-body endocrine and metabolic disorder, not just an ovarian issue. The diagnostic criteria remain the same, but the new name better describes what is actually happening biochemically.
How are thyroid problems and PMOS (PCOS) connected?
Thyroid dysfunction and PMOS share four primary root drivers: insulin resistance, chronic inflammation, HPA-OT axis dysregulation, and nutrient depletion. Women with Hashimoto’s are 2.4 times more likely to also have PMOS, and approximately 25% of women with PMOS have Hashimoto’s. The two conditions feed each other biochemically, which is why treating them in isolation rarely works.
Why am I more likely to have PMOS if I have Hashimoto’s?
Hashimoto’s and PMOS share inflammatory pathways. The same pro-inflammatory cytokines (TNF-alpha, IL-6) that drive immune attack on the thyroid in Hashimoto’s also stimulate theca cells in the ovaries to overproduce androgens, which is the central feature of PMOS. Additionally, a sluggish thyroid lowers SHBG and slows insulin clearance, both of which worsen PMOS symptoms.
Can functional nutrition help with both thyroid disease and PMOS?
Yes. Because both conditions share the same upstream root drivers, a functional nutrition approach addresses them simultaneously rather than chasing each set of symptoms separately. Key strategies include stabilizing blood sugar, reducing inflammation, supporting the HPA-OT axis, improving gut health, and repleting key nutrient cofactors like selenium, zinc, magnesium, vitamin D, inositols, and omega-3s.
What is the HPA-OT axis?
The HPA-OT axis stands for hypothalamic-pituitary-adrenal-ovarian-thyroid axis. It describes the bidirectional signaling between your brain, adrenal glands, ovaries, and thyroid. When one system is stressed or dysregulated, the others are affected. Chronic stress and elevated cortisol disrupt this entire axis, which is why stress management is foundational to treating both PMOS and thyroid disease.
References
Cree-Green M, Teede H, et al. (2026). Polyendocrine Metabolic Ovarian Syndrome: a global rename consensus. The Lancet. doi: 10.1016/S0140-6736(26)00717-8
Hu X, Chen Y, Shen Y, et al. (2022). Correlation between Hashimoto’s thyroiditis and polycystic ovary syndrome: A systematic review and meta-analysis. Frontiers in Endocrinology, 13:1025267. doi: 10.3389/fendo.2022.1025267
Batóg G, Dołoto A, et al. (2023). The interplay of oxidative stress and immune dysfunction in Hashimoto’s thyroiditis and polycystic ovary syndrome. Frontiers in Immunology, 14:1211231. doi: 10.3389/fimmu.2023.1211231
Kanbour S, Dobs AS. (2025). An endocrinological perspective on polycystic ovarian syndrome. Molecular and Cellular Endocrinology. doi: 10.1016/j.mce.2025.112498
