There is a kind of exhaustion that feels different….
Not just “I didn’t sleep well.”…
Not just “I’ve had a big week.”….
But the kind where walking up a single flight of stairs feels harder than it should. Where you need an afternoon sleep to function. Where your body feels heavy, and your thinking feels slower, and you quietly wonder if this is just what adulthood feels like.
A few years ago, a woman came to see me several months after her pregnancy. She had recently been diagnosed with Hashimoto’s thyroiditis. She felt flat, foggy, and confused about how quickly things had shifted.
As we went back through her history and reviewed her previous blood work from pregnancy, something stood out.
Her iron had been on the low end of normal. Her ferritin — her iron stores — had been sitting very low in range.
Technically normal.
But not robust.
And it made me reflect on how often this trio is overlooked: ferritin, thyroid function and energy.
First, What Is Ferritin?
Ferritin is a protein that stores iron in your body.
When we measure ferritin on a blood test, we’re not measuring the iron circulating in that moment — we’re measuring your reserves. Your backup supply. Your stored resource.
Iron is required for far more than preventing anaemia. It is essential for:
- Carrying oxygen around the body
- Producing ATP (your cellular energy currency)
- Supporting thyroid hormone production
- Assisting the conversion of T4 into active T3
- Supporting healthy hair growth and immune resilience
Many pathology laboratories list a ferritin reference range of approximately 15–150 µg/L for women.
So if someone’s ferritin sits at 18, 22 or 30 µg/L, they are told it is normal.
And technically, it is…… But clinically, many women begin to experience symptoms when ferritin drops below about 40–50 µg/L.
That’s not anaemia. That’s under-resourcing. And there’s a difference.
Why This Matters for the Thyroid
Thyroid physiology is more detailed than a single number.
The enzyme that helps produce thyroid hormone — thyroid peroxidase — is iron-dependent. Without adequate iron, it simply doesn’t function optimally.
Iron is also involved in the conversion of T4 (the storage thyroid hormone) into T3 (the active hormone your cells actually use).
So if ferritin is low, the thyroid may not be failing… it may be struggling.
The numbers can remain inside range. TSH may look acceptable. Free T4 may be fine.
But the system may be compensating. And compensation requires energy.
When that compensation continues for long enough — especially alongside pregnancy demands, stress, sleep disruption and immune shifts — the terrain becomes more vulnerable.
Now, I’m not saying low ferritin causes Hashimoto’s. Autoimmune thyroid disease is multifactorial — genetics, gut integrity, immune regulation, stress load and environmental triggers all play a role.
But I am saying this:
Iron status is part of how well your body is resourced.
And resources matter.
Energy Is the Final Output
When ferritin is low, oxygen delivery is reduced.
When oxygen delivery is reduced, mitochondrial ATP production declines.
When ATP production declines, fatigue appears. Add even subtle thyroid strain to that picture, and the exhaustion can feel disproportionate.
Not dramatic. Not diagnosable. But very real.
And this is where so many people feel dismissed. Because nothing has crossed a red flag threshold. Yet the body is clearly asking for support.
This Is the Difference in Lens
The medical system is designed to detect disease once it has established.
And it does that incredibly well.
My work sits slightly earlier in the timeline. I ask:
Is this ferritin optimal for this woman at this stage of life?
Is her thyroid well-supported?
Is this body thriving… or quietly coping?
Preventative medicine is not about searching for problems. It’s about strengthening physiology before dysfunction becomes entrenched.
When I look back at cases like this, what stands out isn’t failure. It’s opportunity.
Opportunity to nourish iron stores earlier.
Opportunity to reduce strain.
Opportunity to build resilience in a body that was already working hard.
You Deserve Robust, Not Just “In Range”
If you’ve ever been told your iron is normal but you’re still exhausted… or your thyroid is fine but you feel slower than you used to…
It may not mean something is terribly wrong. It may simply mean your physiology needs resourcing
Normal is a statistical concept. Vitality is a lived experience. And ferritin, thyroid and energy are intimately connected in that experience.
This is why I read patterns. This is why I look at trends. This is why I don’t wait for a diagnosis before supporting the terrain.
Because thriving is not the absence of disease. It’s the presence of resilience.
Warmly,
Teressa,
Naturopath +Biochemist
Ready to kick start Gut Health? Book a Call!
This is how gut microbes can influence weight!
Probiotics can help you gain weight or lose weight by interacting with our genetics, food and metabolism.
And yes, I did say lose or gain weight……..
Firstly, let me explain that the trillions of microbes in the gut need to be varied, meaning that there should be a large variety of species. There are many different species (or breeds) of microbes, and they all have their place in aiding health — the more variety and balance, the better health results.
Back to the weight loss or weight gain issue….
Do you eat yogurt and berries for breakfast? Thinking that it’s helping you lose weight?
Well, Lactobacillus acidophilus (like the species found in yoghurt) has been connected to weight gain.
I am not saying throw your yoghurt and berries in the bin. Instead, I am suggesting looking at the overall picture. If Lactobacillus acidophilus is the predominant micro-organism of the gut, then weight gain can result.
It is about the variety of species of gut microbes. Imagine if we only have trained german shepherd guard dogs in the world. It may be a safe world, but I am sure that other breeds may be more suitable as a family pet.
While Lactobacillus acidophilus is associated with weight gain, other Lactobacillus species correlate with weight loss.
Species like Lactobacillus plantarum, Lactobacillus gasseri, and Bifidobacteria animalis have been found to support weight loss.
Want to lose weight?
Look at your gut flora to support your goal.
Tests can be performed to identify the predominant species of the gut, and specific species can be utilised to support weight changes.
Want more information about your gut health?
Or want to look at all the factors contributing to weight gain, I’d love to be able to help.
