95. Low Ferritin After 40: Do You Really Need Iron? What Your Labs Aren’t Telling You

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You were told your iron is low – but is that really true? In this episode, Claudia breaks down why low ferritin does not automatically mean iron deficiency, why so many women are incorrectly told to take iron supplements, and how incomplete lab testing leads to more confusion and symptoms.

You’ll learn:

Why ferritin alone does not tell the full iron story
Key iron labs most providers miss (serum iron, transferrin, iron saturation, TIBC/UIBC)
Additional labs that are essential to assess iron status
Why iron supplements can make symptoms worse
Common causes of low iron and low ferritin in women over 40
How heavy periods, low progesterone, and fibroids affect iron status
The role of gut health, stomach acid, and stress in iron absorption
What a root-cause approach to low iron actually looks like

Ona’s Natural Progesterone Cream (I recommend Luna Pro 10 or Luna Pro 20)

Iron and Cell Damage

Limitations of Serum Ferritin in Diagnosing Iron Deficiency

Low Stomach Acid and Low Iron

Low Ferritin Doesn’t Automatically Mean You Need Iron

If you’ve ever been told “your iron or ferritin is low” and you should take an iron supplement…this episode is for you.

I see this often — women taking iron on their own, or because a provider told them to – without anyone asking why iron is low in the first place…or if it IS, in fact, low.

Iron is not a benign supplement and low ferritin does not automatically mean you need to take iron.

Today I want to break down:

Why most iron testing is incomplete
Why iron supplements can backfire
And what causes low iron or anemia in women over 40

Why Ferritin Alone Is an Incomplete Iron Test

Let’s start with the biggest issue.

Most doctors only test ferritin, even those in the functional and longevity space.

Ferritin is an iron storage marker — that’s it. It tells us how much iron is stored, not:

how well you’re absorbing iron
how well you’re transporting it
or whether your body can actually use it

If ferritin is low, that’s one piece of the puzzle. And a good provider knows to dig deeper.

The Full Iron Panel You Actually Need

To understand iron properly, you need a full iron panel, including:

Serum iron – what’s circulating right now
Transferrin – the transport protein that moves iron
Iron saturation – how full that transport system is
TIBC (total) / UIBC (unsaturated) – iron-binding capacity

And you want to look at how iron is actually affecting oxygen delivery and red blood cell production.

So they should also be looking at a CBC (Complete Blood Count)

This shows how iron status is functionally impacting the body. Key markers:

Hemoglobin – oxygen-carrying capacity
Hematocrit – percent of blood made up of red cells
Red Blood Cell count – number of red blood cells
MCV – average size of red blood cells
MCH / MCHC – how much hemoglobin is inside each cell

Why B12 and Folate Must Be Tested with Iron

Vitamin B12 and Folate – because low hemoglobin does not always mean iron is the issue. Low B12 or folate can:

Cause anemia
Create fatigue, shortness of breath, weakness
Alter MCV (often high)
Mimic iron deficiency symptoms

If a provider skips B12, they can easily mislabel someone “iron deficient” and give iron when the real issue is methylation or absorption.

The Role of Inflammation in Iron Labs

Inflammation Markers

CRP (hs-CRP)
Sometimes ESR

Inflammation can:

Raise ferritin falsely
Lower serum iron
cause iron to be present, but unavailable

Thyroid Function and Iron Are Closely Connected

Thyroid Markers

Iron and thyroid are tightly linked.

Low iron can impair:

T4 → T3 conversion

So I like seeing a full thyroid panel.

Why Copper Matters for Iron Metabolism

Copper (and Ceruloplasmin)

Copper is required to:

Mobilize iron
Load iron onto transferrin
Prevent iron from getting trapped in tissues

Low copper can look like iron deficiency even when iron intake is adequate.

So a provider “your ferritin is low, take iron” is such an oversimplification — and why so many women stay tired even while supplementing.

It’s not about chasing numbers. It’s about understanding the physiology behind the numbers.

Why Iron Supplements Can Make Symptoms Worse

The other thing to consider is iron is a powerful oxidizer. Too much iron — or iron taken when it’s not needed — can cause:

Fatigue
Constipation
Nausea
Gut irritation
Increased inflammation
Oxidative stress or cell damage

Iron also feeds pathogens. Certain bacteria, parasites, and even yeast love iron.

So if you’re dealing with gut imbalances or chronic inflammation and you add iron on top of that? You can feel worse.

We are very cautious with iron — especially taken long term.

Common Root Causes of Low Ferritin in Women Over 40

So if you are seeing low ferritin in your labs, that can be a signal that you

Have Inflammation or hidden infections in the gut – they compete with you for iron
Poor digestion or low stomach acid – you can eat iron-rich foods and not absorb them
Have too much stress impairing absorption – stress slows down digestion and nutrient absorption
Aren’t consuming enough heme iron, which is found in animal protein like red meat
Hormonal issues driving blood loss, like low progesterone so you have unopposed estrogen and heavy periods – it’s why most women over 35 IMO should consider progesterone therapy (if you can’t get it from a provider, then consider a topical cream like Ona’s Natural – it’s the only brand I currently recommend because it comes in 100 and 200 mg formulas which is the standard dosing for progesterone and you can titrate up as needed – some women need to apply the cream 4 times per day – morning, mid morning, afternoon, evening and take upwards of 400 mg to feel good
Fibroids or polyps – these require imaging, possible removal, increase in progesterone, mineral balance, and proper estrogen detoxification

If we don’t address the root cause, iron supplements become a band-aid — or sometimes gasoline on the fire.

What Real Iron Support Actually Looks Like

Real iron support looks like:

Supporting hormones to reduce blood loss
Improving digestion and stomach acid
Supporting mineral balance
Increasing heme iron intake
Reducing inflammation so iron can be utilized
Screening for gut infections if necessary

Sometimes iron is needed — but usually short term, and always with a plan.

The Bigger Question: Why Is Iron Low in the First Place?

So if you’ve been told you have low iron or low ferritin…or you’re taking iron and still not feeling well, know that there’s more to the story.

Inside The Perimenopause Method, we assess:

Full iron panels — not just ferritin, the other markers I mentioned
Mineral status and stress load
Thyroid and hormones
Digestion and gut health

So we can answer the real question: WHY is iron low in the first place?

If this episode resonated, please share it with a friend and check out the link in the show notes to apply to work with us.

Until next time.

Claudia Petrilli is a Functional Health Coach, Integrative Nutrition Coach, and creator of The Perimenopause Method — a high-touch program helping ambitious women 40+ support their hormones, restore energy, mood, and feel good in their bodies again.

After years of struggling with debilitating periods, thyroid issues, a pituitary tumor, and a rocky start to perimenopause, Claudia knows exactly what it’s like to be dismissed by doctors and overwhelmed by conflicting advice. Her own healing journey led her to a functional health approach — and now she helps women cut through the noise, advocate for themselves, and finally feel like themselves again.

When she’s not deep in client labs or recording her podcast Perimenopause Simplified, you’ll find Claudia hanging at home with her partner Mike and their rescue pup, Dawson — the real star of the show.

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