If you’re in your late 30s or 40s and dealing with anxiety, heart flutters, breathlessness, crushing fatigue, poor sleep, or feeling wired but exhausted, you should check your iron levels and remember normal does not equal to optimal.
Because low iron is one of the most missed, dismissed, and misunderstood drivers of how crap women feel in perimenopause.
And no, this is not only about “eating more red meat”.
Iron Is Not a “Nice to Have” Mineral
Iron is essential for:
- Oxygen delivery to your brain and muscles
- Energy production (ATP)
- Neurotransmitter production
- Thyroid hormone conversion
- Nervous system regulation
When iron is low, your body is literally running on less oxygen. Your brain doesn’t like that. Your nervous system doesn’t like that. Your hormones definitely don’t like that.
Low Iron and Anxiety: What’s the Connection?
This is where so many women get mislabelled as “anxious”, “burnt out”, or “high stress”.
Low iron can cause:
- Racing heart
- Shortness of breath
- Light-headedness
- Internal shakiness
- Poor stress tolerance
- Panic like symptoms
Sound familiar?
Your brain interprets low oxygen as danger. That switches on your stress response.
I see this all the time: women medicated for anxiety when the real issue is ferritin sitting in the gutter.
Iron and Perimenopause
Perimenopause already brings:
- Fluctuating oestrogen
- Heavier or more frequent periods
- Shorter cycles
- Poor sleep
- Increased inflammation
Now add low iron to the mix.
Heavy periods alone can drain iron stores fast. Even “normal” periods can be enough to cause deficiency when hormones are changing.
You can have “normal haemoglobin” but low ferritin. Doctors often miss this.
Ferritin is your iron storage. When it’s low, symptoms show up long before you’re technically anaemic.
Low Iron and Thyroid: The T3 Problem
This one matters. Iron is required to convert T4 (inactive thyroid hormone) into T3 (active thyroid hormone).
Low iron = poor T4 → T3 conversion.
So you can have:
- Normal TSH
- Normal T4
- Low T3 symptoms
Which look like:
- Fatigue
- Cold intolerance
- Brain fog
- Weight gain
- Low mood
- Exercise intolerance
Women get told “your thyroid is fine” , meanwhile iron deficiency is blocking hormone activation.
Iron also supports thyroid peroxidase (TPO), an enzyme needed to make thyroid hormone in the first place.
Other Symptoms of Low Iron (That Women Normalise)
- Constant fatigue
- Needing naps but still feeling tired
- Hair shedding
- Weakness
- Restless legs
- Poor concentration
- Exercise feels harder than it should
- Headaches
- Pale skin
- Cold hands and feet
If you’re ticking several of these boxes, this isn’t coincidence.
Why Iron Can Be Low (Even If You Eat Meat)
Low iron is not always about diet.
Common causes I see in practice:
1. Heavy or Frequent Periods
This is the biggest one in perimenopause. Blood loss = iron loss.
2. Poor Absorption
You can eat iron and still not absorb it if:
- Stomach acid is low
- You have gut inflammation
- You’ve had SIBO
- You take PPIs or antacids
- You drink coffee or tea with meals
3. Chronic Stress
Stress increases inflammation and hepcidin, a hormone that blocks iron absorption and release.
4. Under-eating or Dieting
Low calories = low micronutrients. Years of dieting catch up in perimenopause.
5. Inflammation
Iron can be “locked away” in storage and unavailable for use. Blood tests may look borderline, but symptoms are loud.
6. Pregnancy History
Many women never fully replete iron after pregnancies and years later feel the impact.
7. Endometriosis or Fibroids
Often overlooked contributors to iron loss.
What To Test?
Do not accept “iron is fine” without seeing numbers.
At minimum, you want:
- Ferritin
- Haemoglobin
- Transferrin saturation
Ferritin below ~40–60 µg/L can already cause symptoms in women. Many feel best closer to 70–100.
If you’re perimenopausal, anxious, exhausted, struggling with weight, sleep, or exercise tolerance, low iron needs to be part of the conversation.
You need to understand why your body is struggling and fixing the root cause.
I’ve lived this. I see it daily in the clinic. And I can tell you, when iron is addressed properly, women don’t only feel “a bit better”.
They feel like themselves again.
If this hits home, don’t ignore it. Your symptoms are not random. They’re information.
References:
Firquet, A., Kirschner, W., & Bitzer, J. (2017). Forty to fifty-five-year-old women and iron deficiency: Clinical considerations and quality of life. Gynecological Endocrinology, 33(7), 503–509. https://doi.org/10.1080/09513590.2017.1306736
Garofalo, V., Condorelli, R. A., Cannarella, R., Aversa, A., Calogero, A. E., & La Vignera, S. (2023). Relationship between iron deficiency and thyroid function: A systematic review and meta-analysis. Nutrients, 15(22), 4790. https://doi.org/10.3390/nu15224790
Karatepe, B. A., Yıldız, S., & Yıldırım, T. T. (2025). Iron, emotion, and awareness: Exploring alexithymia and anxiety in anemic women. Medicina, 61(8), 1359. https://doi.org/10.3390/medicina61081359
National Institutes of Health, Office of Dietary Supplements. (2025). Iron: Fact sheet for health professionals [Fact sheet]. U.S. Department of Health & Human Services. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
Pino, J. M. V., da Luz, M. H. M., Antunes, H. K. M., Giampá, S. Q. C., Martins, V. R., & Lee, K. S. (2017). Iron-restricted diet affects brain ferritin levels, dopamine metabolism and cellular prion protein in a region-specific manner. Frontiers in Molecular Neuroscience, 10, Article 145. https://doi.org/10.3389/fnmol.2017.00145
