Low ferritin is one of those things where people usually go, “I’ll just take iron,” and move on… while the body is trying to coordinate a bunch of systems at once in the background.
I recorded a quick 3-ish minute video on this here. More context below if you want to go full send nerd with. me on it.
Ferritin is your storage form of iron, but it’s not really just a lab value. It reflects how iron is being absorbed, stored, and used across things like thyroid function, oxygen delivery, energy production, and neurotransmitters like dopamine and serotonin.
When it’s low, it rarely shows up as one distinct symptom. It’s more like a cluster that doesn’t feel connected at first. Low energy that doesn’t match sleep. Feeling cold when everyone else is fine. Hair shedding that shows up in the shower and makes you pause for a second. Workouts feeling harder than they used to. Pale skin, darker under-eyes. That general 'something is off!' feeling.
The thyroid piece is a big one that gets missed.
Iron is needed to convert T4 into T3, the active thyroid hormone that actually drives metabolic output. So when ferritin is low, that conversion slows down, and everything can feel like it’s running in a lower gear. This is why someone can have a “normal” TSH and still feel very not normal.
And then it’s not as simple as just taking iron.
There’s a hormone called hepcidin that controls absorption. If it’s high, you absorb less iron no matter what you’re taking. It goes up with inflammation, stress, infections, and sometimes even frequent iron dosing. So you can be doing everything “right” and still feel like nothing is changing.
That’s part of why alternate-day dosing has been getting more attention in research. For some people, spacing iron every other day may allow hepcidin to drop in between doses, which can improve absorption. That’s something to talk through with a provider.
Absorption itself is also not just about the supplement. Stomach acid matters. Gut health matters. Inflammation matters. Even things like SIBO or low-grade gut irritation can reduce iron absorption without obvious digestive symptoms showing up.
Iron also doesn’t exist in isolation once it’s in the body.
Copper is involved in transport. Vitamin A helps mobilize stored iron. B vitamins are needed for red blood cell formation. Protein supports transport and overall metabolic function. So iron can technically be present, but still not really functioning well if those other pieces are off.
Stress layers into this too (but of course it does!). When stress is high for a long time, digestion changes, absorption changes, and the body shifts resources away from storage and repair. Ferritin starts reflecting that overall state more than just intake.
Now the part that confuses people the most: high ferritin with normal or low iron...
Ferritin goes up in two very different scenarios, and they get mixed all the time. One is true iron overload situations where storage is actually high. But the more common one in practice is inflammation-driven ferritin.
Ferritin is also an acute phase reactant, meaning it rises when the body is dealing with inflammation, infection, stress, or immune activation. So you can have high ferritin but low serum iron or low-normal iron because the body is basically holding onto iron and not letting it circulate or be used properly.
That’s why symptoms still matter a lot here. The system can look fine or even high on paper while functional iron availability is actually lowww.
I saw this recently with a client who had been taking iron for months with basically no change. A few things were happening together — gut irritation affecting absorption, coffee timing interfering with uptake, and a stressful season that had shifted digestion and appetite without her really noticing. None of it was a huge deal individually, but enough small things stacking created a bottleneck. Once we adjusted the system around the iron instead of just focusing on iron itself, things finally started moving and her hypothryoidism-like symptoms improved 90%.
And that’s usually what this ends up being -- a handful of small inputs that no one is putting together.
A full iron panel usually includes ferritin, serum iron, TIBC, transferrin saturation, hemoglobin, and hematocrit. So you’re looking at storage, circulating iron, transport capacity, and oxygen-carrying output. This helps show whether iron is low, not being absorbed, not being transported well, stuck in storage, or whether the system has been under enough strain that blood markers are starting to reflect it too.
This is educational only and not medical advice — just context so you can have a more informed conversation with your provider.
This whole space — women’s physiology, a fire metabolism, sexy labs, training, nutrition, all the weird under-the-surface stuff that actually explains what’s going on — is my Roman Empire. I think about it a lot. Probably more than is normal. But also… it kind of explains everything.
I’m really glad you’re here!
And stay tuned until next week because we’re going into a hot button topic, especially for the perimenopause / menopause crowd. It’s one of those things that gets oversimplified online, and the nuance is where everything actually changes.
This is the kind of thing I spend a lot of time doing with clients — putting all the pieces together so it’s not one person talking nutrition, another talking fitness, another giving health advice that doesn’t always line up. It becomes one streamlined plan that actually fits the body in front of us and your LIFE, which is where things finally start to make sense and why it's so successful! If you want support like that, you can apply for 1:1 coaching here. I’ll be in touch after you apply to talk through timing and see if it’s a good fit on both sides.
And if 1:1 isn’t the right next step for you right now, there’s also The Metabolic Edge — my monthly membership community — reopening for June enrollment on May 26th. It’s $59/month, and you can cancel anytime. Inside, it’s a mix of workouts, meals, workshops, guest experts, and coaching calls, plus a community of women who are all working on the same thing -- feeling better in their bodies and actually following through on their goals.
Stay wild + well,
Tara
P.S. In case you missed it ...
This post about abs
And this one on how I finally got my head right and reversed 4 chronic conditions
P.P.S. Things I'm loving lately
NMN -- have taken for about 7 years now. Originally got into it through the NAD+ / cellular energy research rabbit hole, and it’s one of the few things that just stayed in my stack because of how it supports energy metabolism at the cellular level and helps offset age-related decline. This one is tasteless and 3rd party tested.
These electrolytes. I get an adequate amount of sodium through my diet usually so unless it's a sauna or otherwise extra sweaty day, I need more of the other electrolytes and less sodium in order to keep my water retention at bay (I'm a big retainer of water if I'm not careful). These are my fav. for the not-super-sweaty days. Great ingredient quality and I love the taste, so it helps me drink more water. Haha.
Spa, classical, and dinner jazz music. I don't care WHAT I'm doing, if I want to romanticize the heck out of my life in that moment, I throw on one of those and immediately all my problems disappear. I mean, not really, but you understand. Try it! When you shower or do skincare, when you cook or clean or drive. Lmk what you think.