The Conditions That Get Missed in Midlife Women
Author: Serena Schembri | Clinical Nutritionist (BHSc, CPN)
Published: April 2026
Reading time: 8 minutes
Published: April 2026
Reading time: 8 minutes
You feel exhausted. You can't think straight. You've gained weight even though nothing has changed. Your hair is thinning. You have mood swings. You're sleeping badly. And someone, a friend, or even an Instagram post, says it's perimenopause.
Maybe it is. But that might not be the whole story.
Hormonal changes in perimenopause are real and important, but this explanation can be limiting. It can stop further investigation and prevent the identification of other causes or treatments.
Perimenopause is often used as an umbrella term for any symptom a midlife woman has. This is a problem because when everything is blamed on "hormones," other treatable conditions can be overlooked.
Underactive thyroid is the most common misdiagnosis.
There is a huge overlap between perimenopause and thyroid problems, especially hypothyroidism.
Fatigue. Brain fog. Weight gain. Mood changes. Hair thinning. Dry skin. Anxiety. Sleep disruption. Cold intolerance. Low libido.
Every single one of these can be caused by perimenopause. And every single one can be caused by an underactive thyroid. Or both, happening at the same time.
This is not rare. The most common cause is Hashimoto's thyroiditis, an autoimmune condition where the immune system attacks the thyroid gland. Hashimoto's often starts during hormonal changes, including perimenopause.
Why does it get missed?
The symptoms look identical. That's the first problem.
The second problem is how thyroid function is usually tested. Standard screening often stops at TSH, just one number. But a "normal" TSH does not rule out thyroid problems. It does not show what is happening with free T3 (your active thyroid hormone), free T4, or whether your immune system is making antibodies against your thyroid.
The third problem is oestrogen. When oestrogen levels change during perimenopause, they increase thyroid-binding globulin (TBG), a protein that binds and inactivates thyroid hormones. So even if your thyroid makes enough hormone, your body may not be able to use it all. You can have a "normal" TSH and still have low thyroid function.
The HRT blind spot
If you've started hormone replacement therapy and are still exhausted, foggy, and gaining weight, your thyroid needs investigation. It should not be dismissed or chalked up to "the adjustment period."
HRT can help a lot, but it is just one part of the solution. If your thyroid is not functioning well, no amount of oestrogen or progesterone will fully restore your energy, metabolism, or mental clarity. This is such a common and often missed issue that it needs special attention.
A woman presents with debilitating fatigue, brain fog, low mood, breathlessness on exertion, and thinning hair. She's told it's perimenopause. Nobody checks her ferritin, or they check haemoglobin, see it's "normal," and move on.
Here's the thing: ferritin can be very low, meaning your iron stores are completely depleted, while your haemoglobin is still normal. By the time your haemoglobin drops, you may have been running on empty for months or even years. Iron is essential for carrying oxygen to the brain, making neurotransmitters like dopamine and serotonin, and producing energy. Low iron, even without anaemia, can show up as:
- Crushing fatigue that rest doesn't fix
- Poor concentration and brain fog
- Low motivation and flat mood
- Hair thinning and loss
- Breathlessness on stairs or during exercise
- Restless legs
- Feeling cold
Does this sound familiar? That's the problem. These symptoms are just like those of perimenopause. Heavy or irregular periods during perimenopause can worsen iron loss. This is why it's important to get bloodwork done. Not just haemoglobin but full iron studies, including ferritin. It's one of the simplest and most impactful tests for correcting perimenopause symptoms, too.
Chronic stress, HPA axis dysfunction, and burnout can produce symptoms that are virtually indistinguishable from perimenopause.
Fatigue. Cognitive decline. Mood instability. Weight changes. Low libido. Disrupted sleep. Loss of motivation. Feeling wired but tired.
Many women in their 40s have both perimenopause and burnout. The hormonal changes come after years of stress and doing too much with too little support. The nervous system has relied on adrenaline for so long that when hormones shift, there is nothing left to help. Burnout is not just feeling tired. It is a physical state characterised by changes in the HPA axis, altered cortisol patterns, increased inflammation, and slower recovery. It affects the same neurotransmitters serotonin, dopamine, and GABA, which perimenopause also disrupts.
Untangling which is which requires testing, not guessing.
These conditions coexist, and that's the point.
Perimenopause, thyroid problems, iron deficiency, and burnout do not wait for their turn. They often happen together and make each other worse. Treating just one and ignoring the others will not help you feel better.
A woman with Hashimoto's who is also in perimenopause will not feel better on HRT alone if her thyroid antibodies are elevated and her free T3 is suboptimal.
A woman with depleted ferritin who is also burnt out will not recover with stress management alone if her iron stores are empty.
A woman in perimenopause who also has low iron and undiagnosed thyroid problems will keep feeling unwell, no matter how many supplements she takes, how healthy her diet is, or how much she rests, until all the causes are found and addressed.
This is why I do thorough testing. It is not to make things complicated or to over-investigate. A list of symptoms alone cannot show what is really causing your problems. The test results can.
The tests that can explain more
Here is what I think is the minimum set of tests for a woman in her late 30s or 40s who has fatigue, brain fog, mood changes, or unexplained weight gain:
Iron studies, including ferritin, transferrin saturation, and serum iron.
- Thyroid panel: TSH, free T3, free T4, and thyroid antibodies (anti-TPO and anti-TG). A TSH-only test is not sufficient, particularly during perimenopause.
- Vitamin D: low levels are linked to fatigue, mood changes, and increased inflammation.
- B12 and folate: essential cofactors for neurotransmitter production and methylation. Particularly relevant if you carry MTHFR variants.
- Magnesium: RBC magnesium, if available, as serum magnesium is less reliable.
- Inflammatory markers: CRP, ESR. Elevated baseline inflammation can independently drive fatigue, mood disruption, and brain fog, regardless of hormonal status.
- Fasting glucose and HbA1c: metabolic health baseline. Insulin resistance increases during perimenopause and can drive weight gain, fatigue, and brain fog.
The bigger picture
Perimenopause needs proper attention, investigation, and support. But it is not the only thing happening in your body. If every symptom is blamed on perimenopause, thyroid problems can go undiagnosed, iron deficiency can go untreated, burnout can be missed, and women can spend years feeling unwell while being told they are "normal." You deserve better than normal. You deserve a complete picture and a plan built on data, not assumptions.
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