Perimenopause or Thyroid? How to Tell the Difference
Perimenopause or Thyroid? How to Tell the Difference
If you are exhausted, foggy and gaining weight, and you cannot work out whether it is perimenopause or your thyroid, this post might be for you.
It is one of the most common questions I get in clinic from women in their late thirties, forties and early fifties. "Is this perimenopause, or is it my thyroid?" It usually arrives with a long list. The tiredness that sleep does not fix. The weight that has crept on without any change in what you eat. The brain fog that has you walking into a room and forgetting why. The mood that is lower, flatter or snappier than it used to be.
If that is you, I want you to know something first. You are not imagining it, you are not going mad, and you are not just "getting older". Your body is sending you a lot of signals at once, and the tricky part is that two very common conditions send almost exactly the same ones.
Quick answer: Perimenopause and thyroid problems share many symptoms, including fatigue, weight changes, brain fog, low mood, poor sleep and changes to your periods, which is why they are so often confused. Perimenopause tends to bring hot flushes, night sweats and cycle changes, while an underactive thyroid more often brings feeling cold, dry skin, hair thinning and constipation. You can have both at the same time, so the only reliable way to tell is a proper history and the right testing.
Why these two get mixed up so often
Think of your thyroid and your sex hormones as colleagues who share an office. When one has a bad day, the other hears all about it. Your thyroid helps set the pace of your whole body, including your energy, temperature, digestion, mood and menstrual cycle. Oestrogen and progesterone influence how much thyroid hormone is available, how well it works, and how your body handles stress. When one shifts, the other often wobbles too.
Timing adds to the confusion. Thyroid conditions are more common in women, and they tend to show up at the same stages of life when hormones are already changing, including after pregnancy and through the forties. Perimenopause can begin in the late thirties or early forties, years before your periods stop. So you can easily be in the middle of both, and it is not always obvious which is leading the show.
The symptoms they share
Here is the overlap, and it is a big one. All of these can come from perimenopause, a thyroid problem, or both:
Fatigue that does not improve with sleep
Weight gain, especially around the middle
Brain fog and poor memory
Low mood, anxiety or irritability
Disturbed sleep
Hair thinning or hair loss
Changes to your periods, including heavier or irregular bleeding
Low libido
Dry skin
Aches, stiffness and joint pain
If you recognise most of this list, you are in very good company, and it is a good reason to look properly rather than guess. If fatigue is your biggest symptom, why you are tired all the time even after a full night's sleep goes through the other drivers I look at.
Perimenopause or thyroid: the clues that point one way
There are some patterns that help, though they are clues, not answers.
More typical of perimenopause
Hot flushes and night sweats
Periods that become irregular, shorter, longer or unpredictable
PMS that gets noticeably worse in the week before your period
Waking between 2 and 4am
Breast tenderness
New or worsening anxiety, or feeling "wired and tired"
Vaginal dryness or changes in libido
More typical of an underactive thyroid
Feeling cold when others are comfortable
Dry skin and brittle nails
Thinning of the outer eyebrows
Constipation
Puffy face or a hoarse voice
A slow pulse
A feeling of being slowed down across the board, including your thinking
More typical of an overactive thyroid
Feeling hot and sweaty
A racing or fluttering heart
Shakiness, restlessness or anxiety
Weight loss despite eating well
Loose bowels
Overlap is common, though. Heavier periods can sit behind both perimenopause and an underactive thyroid. Anxiety can come from perimenopause or an overactive thyroid. This is why symptoms alone cannot settle it.
Can it be both?
Yes, and I see it often. A woman may have perimenopause changes and an underactive thyroid at the same time, and each one makes the other feel worse. For example, low thyroid function can disturb ovulation and periods, which can look like perimenopause. In the other direction, shifting oestrogen and progesterone can affect how well your body uses thyroid hormone. Stress and poor sleep add another layer to both.
Autoimmune thyroid disease, most commonly Hashimoto's, is a big player too. It often develops quietly, and your standard thyroid result can look fine for years while the antibodies are already rising. If thyroid disease runs in your family, or you have other autoimmune conditions, it is especially worth checking.
How to tell the difference
This is where a tailored approach beats guessing. Here is how I work it out.
1. Your history and your cycle. I look at how your periods have changed, when your symptoms started, what time of the month they flare, and what else is going on in your life. Tracking your cycle for a few months can show a lot.
2. A proper thyroid assessment. A single TSH result does not always tell the whole story. A fuller picture usually includes TSH, free T4, free T3 and thyroid antibodies, which can show autoimmune thyroid disease before your TSH moves out of range. Your ferritin, vitamin D, B12 and other nutrient levels matter too, because they are needed to make and use thyroid hormone.
3. Looking at your hormones in context. Perimenopause is mainly recognised by your age, symptoms and cycle changes. One blood test of hormones such as FSH can be misleading, because your levels swing from day to day and month to month during this stage. Depending on your history, hormone testing that looks at patterns across a cycle can help us understand what is happening, and I use it as one tool within a broader picture rather than a stand alone answer. You can read about the options on our functional testing page.
4. Your gut. This is the piece that so often gets missed. Your gut helps convert thyroid hormone into its active form, absorb the nutrients your thyroid relies on, and clear used oestrogen from your body. An unhappy gut can disturb both systems at once. Autoimmune thyroid disease is also linked with gut health, including coeliac disease and gut inflammation. If you are bloated, constipated or react to foods, it is worth looking at. Signs of poor gut health you might be ignoring and 10 causes of constipation and what to do about each one are good places to start.
What helps, whichever it is
The right plan depends on what we find, and I would never recommend supplements for a thyroid without knowing what your thyroid is doing. That said, there are foundations that support both your thyroid and your hormones, and these are the ones I layer in first.
Protein and steady blood sugar. Start the day with protein, keep your meals regular, and have your coffee after food. Blood sugar swings make fatigue, mood and hot flushes worse.
Plenty of colourful plants and fibre. They feed your gut bacteria and help clear oestrogen.
The nutrients your thyroid needs. Selenium, zinc, iron, vitamin D and B12 all play a part, and iodine matters but needs care, particularly with autoimmune thyroid disease, so I test and tailor rather than guess.
Gut support. Sorting out digestion, bowel function and any imbalance, in the right order.
Strength training. Muscle supports your metabolism, your bones and your mood through perimenopause. Perimenopause is not just hot flushes explains more.
Stress and sleep. Your thyroid and your sex hormones are both very sensitive to a nervous system that has been running on empty.
If your symptoms flare around your cycle, why your PMS is getting worse in your thirties and forties and oestrogen dominance: what it is and what drives it explain how the balance between your hormones plays out. For the broader foundations, how to support your hormone health naturally walks through them. You can also read about how we approach this on our hormone health page, fatigue and energy page, nutritional deficiencies page and gut health page.
When to get checked sooner
Please see your doctor promptly if you have a racing or irregular heartbeat, a lump or swelling in your neck, trouble swallowing, sudden unexplained weight loss, very heavy bleeding, bleeding between periods or after sex, or low mood that feels hard to cope with. If you ever have thoughts of harming yourself, call Lifeline on 13 11 14 straight away. Naturopathic care works well alongside any medical care you need, including thyroid medication.
You do not have to just put up with it
If you have been told "your bloods are normal" and you still feel anything but, there is almost always a reason, and once we find it, we can actually treat it. We can work together to figure out whether it is perimenopause, your thyroid or both, and build a plan that gives you your energy and your clarity back.
If you would like to hear more about this stage of life in person, I am co-hosting the Women's Health Collective on Wednesday 21 October at 6pm in Spotswood, an honest, evidence-informed evening with a panel of women's health experts. Perimenopause is a new season of life, and it is so much easier when you prepare for it.
Book a session here, in person at our Spotswood clinic or by telehealth across Australia, and let's get to the bottom of it.
Frequently asked questions
How do I know if it is perimenopause or my thyroid? Symptoms overlap heavily, so it is hard to tell by symptoms alone. Hot flushes, night sweats and changing periods point more towards perimenopause, while feeling cold, dry skin, constipation and thinning hair point more towards an underactive thyroid. A proper history and testing are the only reliable way to tell.
Can an underactive thyroid cause menopause symptoms? Yes. An underactive thyroid can cause fatigue, weight gain, low mood, brain fog, heavy or irregular periods and low libido, all of which are also common in perimenopause. That is why thyroid function is worth checking whenever perimenopause is suspected.
Can you have perimenopause and a thyroid problem at the same time? Yes, and it is common. Both tend to appear in midlife, and each can make the other's symptoms feel worse. Treating one without checking the other can leave you still feeling unwell.
What thyroid tests should I ask for? A fuller picture usually includes TSH, free T4, free T3 and thyroid antibodies, along with nutrient levels such as ferritin, vitamin D and B12. A single TSH result does not always tell the whole story, so it is worth discussing the right tests for you with your practitioner.
Can gut health affect my thyroid? It can. Your gut helps convert thyroid hormone into its active form and absorb the nutrients your thyroid needs, and autoimmune thyroid disease is linked with gut health and gut inflammation. Looking after your gut supports both your thyroid and your hormones.
Can I support my thyroid and perimenopause naturally? Naturopathic care can be a valuable part of your support, through food, nutrient levels, gut health, stress and sleep. It works best when it is tailored to your results, and it can sit alongside medical care, including thyroid medication, rather than replace it.
