If you’re tired, anxious, itchy, gaining weight, and snapping at the people you love, it’s tempting to land on one explanation. Maybe it’s perimenopause. Maybe it’s your thyroid. Maybe it’s anxiety.
Here’s what I’ve learned: it’s worth not settling on just one. These conditions share so many symptoms that it’s easy to pin everything on a single cause, and I’ve been wrong at times when I have done that. It doesn’t mean something is “wrong with you” or that you have a long list of problems. It means your body is connected, and sometimes more than one of these is quietly contributing to how you feel. Hormones affect far more than our reproductive organs. We have hormone receptors throughout the body, including in the brain, gut, skin, and thyroid, so when one system shifts, others can respond. That’s why I don’t want to just blame sex hormones for everything, and why I prefer to screen for other causes or contributing factors. The goal isn’t to find more things to worry about. It’s to make sure we’re treating the right things and that we haven’t overlooked anything.
Symptoms that can come from more than one place
These are symptoms I look at carefully, because they can come from more than one place:
Fatigue and brain fog: can be linked to changing hormones, an underactive thyroid, poor sleep from anxiety, low iron, gut changes, or B12 deficiency.
Weight changes: can be linked to hormonal shifts, thyroid function, stress, sleep, and blood sugar.
Irritability and mood changes: can be linked to fluctuating estrogen and progesterone, thyroid imbalance, gut issues, and anxiety.
Dry skin, itching, and hair changes: can be associated with declining estrogen, an underactive thyroid, nutrient deficiencies such as low iron, as well as ongoing stress and anxiety.
Anxiety and a racing heart (palpitations): can be associated with perimenopause (estrogen receptors are found throughout the body, as we discussed in Weird Symptoms Nobody Warns You About: The Physiology of Perimenopause), an overactive thyroid, and anxiety.
Poor sleep: can be linked to declining progesterone (which has a natural GABA-supporting effect that helps with sleep), thyroid imbalance, and anxiety. This includes trouble falling asleep, waking in the middle of the night, trouble falling back asleep, and waking up unrefreshed [20, 21].
Feeling hot or cold: can be linked to fluctuating estrogen and progesterone (hot flashes and night sweats), an overactive thyroid (feeling overheated and sweaty), an underactive thyroid (feeling cold), and anxiety.
None of these symptoms points to a single cause on its own, and research reflects that.
Perimenopause is one piece. In a large study of health records from South Korea, women aged 45 to 64 with symptomatic menopausal transition had higher risks of being diagnosed with depression, anxiety, and sleep disorders than matched women without symptoms [22]. A meta-analysis of prospective studies also found that perimenopausal women had higher odds of depressive symptoms and diagnoses than premenopausal women [23]. Thyroid conditions overlap with this stage of life. Thyroid problems are common, especially in women, and one review noted that menopause may change how autoimmune thyroid disease shows up, although studies directly looking at menopause and thyroid function are few [24].
Thyroid and anxiety are also connected. In a small, older study of 169 people with anxiety disorders, blood tests found a thyroid problem in only two, but a history of thyroid disease was reported more often than expected, particularly in people with generalized anxiety. The authors concluded it’s reasonable to ask about thyroid history and consider testing [1]. A 2024 meta-analysis found higher odds of anxiety and depression in people with Hashimoto’s thyroiditis, even when thyroid hormone levels were normal. The authors noted that the studies varied a lot and that publication bias may have exaggerated the effect [2].
What these studies show are associations, which means these conditions often appear together in the same people. That doesn’t mean one is causing the other. But it does give us a reason to screen for them together, rather than assuming there’s one explanation.
What your thyroid needs to do its job
Your thyroid builds its hormones from a handful of raw materials. Iodine is a component of T3 and T4 themselves. Iron matters because thyroid peroxidase, a key enzyme in making thyroid hormone, depends on it, and severe iron deficiency can reduce its activity. Selenium is concentrated in thyroid tissue and is involved in hormone synthesis and metabolism. Zinc, magnesium, and other minerals have also been linked to thyroid function, although how they relate to thyroid disease is still being worked out [10]. If the raw materials are low, the thyroid can struggle even when the gland is healthy, which is why I check nutrients as part of every workup.
Testing: start with the nutrients
If I’m looking at these three things, I always check for nutrient deficiencies. Depending on your history, this can include:
Vitamin B12. Low B12 can contribute to fatigue, brain fog, and low mood, which overlaps with nearly everything. Risk factors include absorption problems in the gut, vegetarian or vegan diets (limited intake), certain medications (eg, metformin, PPIs), and older age. Testing is generally suggested when someone has both a risk factor and a symptom [26].
Vitamin B6, sometimes. Your body’s need for B6 can shift as your hormones do. Estrogen influences how your body processes tryptophan, the building block of serotonin, and B6 is needed at several steps along that pathway. Research on estrogen-containing birth control suggests B6 status can drop when estrogen is higher or changing [14]. There isn’t direct research on how this plays out in perimenopause, so I use it as a reason to keep B6 in mind when mood, sleep, or anxiety are part of the picture. I don’t usually test B6 directly in blood. Instead, it sometimes shows up indirectly through markers on an organic acids panel, like the one included in the DUTCH test, since some of the metabolites along that pathway can reflect B6 status [25]. These markers are best interpreted alongside your symptoms and the rest of your results, not on their own.
Iron, measured as ferritin. Low iron stores can cause fatigue even when you’re not anemic. In a randomized trial of 198 non-anemic women aged 18-53 with unexplained fatigue and low ferritin, fatigue improved more with iron than with placebo [3].
Homocysteine, sometimes. Homocysteine is a marker related to methylation, the process your body uses with B vitamins like B12, folate, and B6, and it can rise when those vitamins are low [13]. In a study of 128 healthy women, homocysteine levels were progressively higher from premenopause through postmenopause and were associated with lower estradiol. Dietary intake of B6 and B12 was also lower in the postmenopausal women [13], and hormone therapy has been associated with lower homocysteine in postmenopausal women [15]. These findings are associations, and there isn’t direct research on using homocysteine to guide care in perimenopause. So I treat it as a clue, not a diagnosis. When it’s elevated, it prompts me to look more closely at B12, folate, and B6 status, and I interpret it alongside your symptoms and the rest of your results. I don’t test it for everyone, but when the picture suggests it, it can help show whether your B-vitamin status needs attention.
Testing: the thyroid, beyond the screening test
When people come to me, their screening test (TSH) is usually in the normal range. That’s often where the story starts, not where it ends.
What TSH actually tells us. TSH is a signal from your brain (the pituitary gland) telling your thyroid to make hormone. When there’s enough thyroid hormone in the blood, the brain turns that signal down, and when there’s too little, it turns it up. That’s what we call a negative feedback loop, like a thermostat. TSH tells us whether the brain thinks your thyroid hormone level is right, but it doesn’t tell us everything about the thyroid itself.
Because of this, when I’m already doing a thorough workup, I generally look at the full panel:
Free T4: the main hormone your thyroid makes and releases, and the one that circulates in your blood. It’s considered the storage or “inactive” form, because your body has to convert it into the active form (T3) before your cells can use it. That conversion happens mostly in tissues outside the thyroid and depends on nutrients such as selenium [10].
Free T3: the active form your cells use. Looking at it alongside T4 helps show whether that conversion is happening as expected.
TPO and thyroglobulin antibodies: antibodies against the thyroid, which can point to autoimmune thyroid disease such as Hashimoto’s. In a 20-year follow-up of a large community cohort, the presence of thyroid antibodies was associated with a greater likelihood of developing hypothyroidism later [9].
Reverse T3: this is the inactive form your body makes from T4. In conventional endocrinology, it isn’t used to guide treatment, and an ATA-commissioned review concluded there’s no evidence supporting that use and no need to measure it routinely, apart from a few rare situations, such as certain rare genetic thyroid conditions and consumptive hypothyroidism [16]. For that reason, I usually check it once, when I’m already running a full panel, to help rule out those rarer possibilities and complete the picture. I don’t routinely retest it, because there’s no good evidence that following it over time improves how you feel.
The presentation I see most often is a normal TSH, normal T3 and T4 (sometimes “suboptimal" levels), and elevated antibodies. Whether to do anything about that is an individual decision. The evidence for treating antibodies on their own is limited, and for people planning pregnancy, a large randomized trial found no improvement in live births when levothyroxine was given to women with antibodies and normal thyroid function [4]. So I discuss options with you openly, including monitoring over time, nutrition and lifestyle support, and, in some cases, a time-limited and carefully monitored trial. We decide together, and we measure how you feel and how your labs respond to help guide treatment.
Testing: the rest of the hormone picture
I also look at the broader hormone picture so I have a good snapshot of what’s going on in your body. This can include cortisol, estrogen, progesterone, LH, FSH, testosterone, and DHEA-S, by blood, urine, or saliva depending on the situation. You can read about this in more detail in my post, Perimenopause and Menopause: Understanding Your Changing Hormones.
Testing: metabolic markers
I also include metabolic markers such as HbA1c, fasting insulin, and a lipid profile, to make sure we’re covering all our bases. Blood sugar and insulin changes can show up as fatigue, irritability, cravings, and anxiety, so they’re worth ruling in or out.
Why the whole picture matters for treatment
When we look at everything together, we can treat the underlying cause (or causes) rather than chase one symptom at a time. In the meantime, I also discuss managing symptoms through diet and lifestyle, and sometimes through nutraceuticals, herbs, and other supportive options. The evidence for these varies, so we talk through what’s known and what isn’t, and we choose together.
My philosophy is that you shouldn’t have to wait to start feeling better while we investigate. Finding the underlying cause isn’t always straightforward. So I aim to support your symptoms along the way while we work on the root cause.
If I only addressed the thyroid, I might miss the iron deficiency. If I only addressed the hormones, I might miss the thyroid. That’s the point of looking broadly.
Supporting the thyroid
There’s a wide range of ways to support the thyroid. Which ones are right for you depends on your results, your history, and your preferences.
Prescription options. Levothyroxine (T4) is the standard treatment for an underactive thyroid, and the American Thyroid Association’s guideline concluded there was no consistently strong evidence that thyroid extracts or combination treatments are better [5]. Desiccated thyroid extract, which contains both T4 and T3, is another option some people choose. In Ontario, naturopathic doctors with prescribing authority, including me, can prescribe it. In two randomized crossover trials, desiccated thyroid and levothyroxine had similar results for most outcomes, though some people preferred the extract [6, 7]. The American Thyroid Association’s 2025 statement does not recommend desiccated thyroid as first-line therapy, but recognizes it as the treatment of choice for some patients and supports personalized care. The same statement notes that the US FDA has identified significant manufacturing problems with these products [8].
In Canada, desiccated thyroid is often obtained through compounding pharmacies, which is where I usually send these prescriptions. As with compounded hormones, this isn’t automatically better or worse than a standard, commercially regulated option. Levothyroxine is a standardized, well-studied product, while desiccated thyroid is animal-derived, so consistency from batch to batch matters and the long-term research is more limited. That said, it can be a reasonable choice for some people, particularly if you’ve tried levothyroxine and feel it isn’t the right fit for you. Either way, it needs the same careful follow-up: regular bloodwork, small adjustments, and attention to symptoms of too much or too little thyroid hormone. Prescribing options depend on your province and your individual situation, and this is a decision we make together, based on your symptoms, your results, and your preferences.
Note: If you’re planning a pregnancy or are pregnant, levothyroxine is the recommended choice. The developing baby’s brain relies largely on the mother’s T4, and desiccated thyroid supplies relatively more T3 and less T4, which could reduce the thyroid hormone available to the baby’s brain [22]. If you’re taking desiccated thyroid and thinking about pregnancy, consult your primary caregiver about switching before you start trying.
Nutrients. Some nutrients supply the raw materials the thyroid uses, and when levels are low, correcting them is a reasonable step. Where possible, we try to ensure adequate intake through food. Selenium has been studied in Hashimoto’s thyroiditis. A Cochrane review of four small trials (463 participants) found that selenium may reduce thyroid antibody levels, but the clinical relevance was unclear, and the authors concluded the evidence was incomplete [18]. Broader nutrition patterns also matter: a 2026 review found that a Mediterranean-style diet was associated with favorable thyroid outcomes, while gluten-free or lactose-free diets didn’t appear to offer significant benefit, and it discussed vitamin D and omega-3 fats as possible helpers in autoimmune thyroid conditions [11]. These are associations and emerging evidence, not proof of cause, and more research is needed.
Botanicals. Botanicals deserve more care than nutrients. Ashwagandha is one I consider and is found in many “thyroid” formulas. In a double-blind, placebo-controlled trial of 50 people with subclinical hypothyroidism, 8 weeks of ashwagandha root extract was associated with significantly improved TSH, T3, and T4 compared with placebo, with a few mild, temporary side effects reported in both groups [17]. That’s encouraging, but it’s a single small, short trial and needs to be repeated before we can draw firm conclusions. How it might work isn’t as well studied as its effect on cortisol. My working understanding is that ashwagandha acts on the stress (HPA) axis, and because the HPA axis can influence signaling from the pituitary gland, including TSH, this may be how it affects the thyroid. That’s a proposed explanation, not a proven one. Because ashwagandha can affect thyroid hormone levels, and liver problems have been reported in rare cases, I never use it without a plan to recheck your bloodwork. It’s a good option for some people, and not for others, especially if your thyroid is already overactive.
Monitoring: finding your sweet spot
If we start any thyroid support, we follow up with bloodwork. The right amount of treatment varies a lot from person to person. What gets one person into their optimal range may not work for another, so I monitor closely and make small adjustments until we find your sweet spot. Too much thyroid hormone can cause symptoms of an overactive thyroid and is associated with risks such as atrial fibrillation, abnormal heart rhythms, angina, and osteoporosis [19].
Reach out right away if you notice: palpitations or a racing heart, new or worsening irritability or anxiety, feeling “wired but tired,” tremor, sweating or feeling overheated, trouble sleeping, or unexpected weight loss. If you have chest pain, fainting, or severe shortness of breath, call 911 or go to your nearest emergency department.
Next steps
If any of this sounds familiar, I offer virtual care for hormone, thyroid, and mental health concerns across Ontario and Manitoba. You can book online or send me a message through the contact form if you have questions first.
Frequently Asked Questions
Can perimenopause cause symptoms that look like a thyroid problem?
Yes. Fatigue, weight changes, mood changes, poor sleep, and feeling too hot or too cold can come from perimenopause, from the thyroid, or both. Because the symptoms overlap, testing can help you find out what’s contributing.
Can a thyroid problem cause anxiety?
An overactive thyroid can be associated with anxious feelings and a racing heart, and research has found higher rates of anxiety in people with autoimmune thyroid disease. That doesn’t mean your anxiety is “just” your thyroid, but it’s a good reason to check.
Why is my TSH normal when I still don’t feel well?
TSH is a helpful screening test, but it only shows the signal from your brain to your thyroid. It doesn’t tell us everything about the thyroid, and your symptoms may have other contributors, such as low iron, B12, or other hormones. That’s why I often look at free T4, free T3, and thyroid antibodies, along with nutrients and hormones.
What tests can help sort out perimenopause, thyroid, and anxiety?
It depends on your history, but a thorough workup often includes nutrients (such as B12 and ferritin), a thyroid panel, a broader look at your hormones, and metabolic markers. We decide together what makes sense for you, based on both symptoms and cost.
Can more than one of these be going on at once?
Yes, and it’s more common than people expect. Hormone receptors are found throughout the body, so changes in one system can affect others. That’s why I look at the whole picture instead of settling on one explanation.
Do you offer thyroid and hormone care in Manitoba and Ontario?
Yes. Dr. Sarah Boulet, ND, offers virtual naturopathic care for hormone, thyroid, and mental health concerns across Ontario and Manitoba. You can book a consultation online or send a message through the contact form on this website.
This post is general information, not medical advice. Please speak with a qualified healthcare provider about your individual situation.
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