What is a good ferritin level for women?

This post goes with episode 2 of The Naturalist Podcast, "Told your ferritin is fine, but still exhausted?" Listen here

Awanui Labs' guidance is that a ferritin below 30 µg/L is low. Above that, it is generally passed as normal, so a result in the 30s is usually not flagged. The range I work to for good function is 80 to 100 µg/L, which is a practice range and not a diagnostic threshold.

• Ferritin: low below 30 µg/L (Awanui). The range I work to is 80 to 100 µg/L.

• Serum iron: 10 to 30 µmol/L (Awanui). The range I work to is 13 to 25 µmol/L.

• Transferrin saturation: 15 to 50% (Awanui). The range I work to is 25 to 40%.

• Haemoglobin: 115 to 155 g/L (Awanui). The range I work to is 135 to 145 g/L.

The ranges I work to are the ones I use in practice, mostly with women who are still menstruating. They are not diagnostic thresholds, and a result outside them does not mean something is wrong. It means it is worth a closer look. Ferritin tends to rise after menopause, so what is right for you changes at different stages. Reference ranges are set by the laboratory, so the range printed on your own report is the one that applies to your result.

What is ferritin?

Ferritin is your iron storage tank. Iron does not only sit in your blood. Your body banks it away, and ferritin is how we measure what is in the bank.

In healthy people, every 1 µg/L of ferritin represents about 8 milligrams of iron in storage.

That bank supplies your energy, your thyroid function, your ovulation and your hair. When stores run low, you tend to feel it long before anything gets flagged. That is why ferritin is the best single marker of your iron reserves.

Why is 35 called normal when the range I work to starts at 80?

A result of 35 sits above the cut-off of 30, so it is not flagged, and nobody looks further. It is also nowhere near 80. At 35, that is roughly 280 milligrams of iron in storage. At 80, it is roughly 640.

The 30 answers one question: is this woman iron deficient? It is a good cut-off for that. It was never meant to answer a different question: is her iron where she needs it to be for how she feels?

You can be told your iron is fine while you are exhausted, because the cut-off is there to catch iron deficiency, not to tell you whether your iron is where you need it.

A result under 30 always points to iron deficiency. If yours is there, take it to your doctor.

What does low ferritin feel like?

• Fatigue that sleep does not fix

• Breathlessness on the stairs, or stamina that has quietly dropped

• Hair shedding

• Brittle nails

• Restless legs, especially at night

• Low mood

That list sounds like half the women you know, which is part of why it gets put down to being busy, stressed or getting older. It can also happen in someone who eats well. It is not a reflection on you or your diet.

A composite from clinic

Let's call her Jess. She is 32 and has endometriosis, with heavy periods. She was exhausted in a way a weekend did not fix, breathless on the stairs, and losing hair in the shower.

Her GP ran bloods and told her everything looked fine. Her ferritin was 35. That is above the cut-off of 30, so it was not flagged, and nobody looked at the rest of the iron panel.

But a 35 in someone bleeding heavily every month tells a different story from a 35 in someone who is not. The number needed context, and the cut-off was never meant to give it.

The next step was not to guess. It was to find out why it was sitting there.

In the women I see who look like Jess, it is often both. The heavy periods keep drawing the stores down, while inflammation props the ferritin up. When we ran the full picture, her CRP showed inflammation. That can lift ferritin, so the 35 was flattering her and her real stores were likely lower. Her transferrin saturation and blood count also showed that the iron was not making it around her body. That was likely adding to her fatigue.

Jess is a composite, a pattern I see often rather than one client.

Why does low ferritin get missed?

There are two reasons.

The cut-off is built to catch iron deficiency. A result that is low for you can still sit above it, so nothing is flagged.

Ferritin on its own does not give the full picture. It rises with inflammation, so a reassuring number can hide a real shortfall. A higher result is not automatically a full tank. That is why it is best read alongside a CRP, an inflammation marker. Ferritin also shows what is in storage, not whether iron is reaching the places that need it.

What is a full iron panel?

A full iron panel is four markers, read together with a full blood count.

Ferritin shows your storage.

Serum iron is the iron circulating right now. It moves through the day with meals, supplements and stress, so it does not mean much alone.

Transferrin is the protein that carries iron. Your body makes more of it when iron is scarce.

Transferrin saturation shows how much of that carrier is holding iron. It measures delivery rather than storage, so it can show a problem even when storage looks fine.

At Awanui, since October 2024, if a doctor ticks "iron studies" on a paper form, the lab runs ferritin only. The guidance is that serum iron, transferrin and transferrin saturation are for specific situations, like anaemia or a ferritin that needs explaining. So if your ferritin comes back in the normal range, the full panel usually isn't ordered. If you would like it, you can ask your doctor to request it, or request it yourself at your own cost. Other labs may differ, so check your own report.

Haemoglobin is the marker most people know, but it shifts last. Energy tends to suffer well before haemoglobin drops far enough to be called anaemia. There is a name for this: hypoferritinaemia without anaemia. Your haemoglobin and blood count can be completely normal, and fatigue, hair loss and low mood can still be there.

Why ferritin matters for endometriosis and PCOS

If you have endometriosis and heavy bleeding, your iron stores are drawn down every month, so stores that were marginal can keep draining cycle after cycle. If you have PCOS (also written as PMOS), fatigue and hair changes are common, and low iron can look very similar. In both, the fatigue often gets put down to the condition itself, and iron is not always looked at properly.

Getting your iron tested in New Zealand

Lab tests here are funded through Health New Zealand, and every lab holds a contract that sets out which tests are funded and when. Your GP works inside those rules, so a well-reasoned request is more likely to get somewhere than a vague one. The Full Picture Handbook has a section on how to ask well for the testing you want.

If a test is not funded, services like i-screen and BodyIQ let you request certain blood tests directly.

Iron tests are best done when you are well and not taking iron supplements. If you have been unwell, or you are taking iron, ask your doctor about timing. Iron is often best tested fasted, first thing in the morning, because serum iron moves around with meals and supplements.

What to do with your result

1. Find your number. Look at your last set of bloods and find the ferritin. Not whether it was flagged, just the number.

2. Find out what was run. Was it ferritin alone, or the full panel? If it was ferritin alone, you have seen part of the picture.

3. Understand why. If ferritin is low, the reason matters more than the number. Heavy bleeding, diet, absorption and inflammation can each produce a low result, and each needs something different.

Consistently high iron results are worth reviewing with your doctor. Taking more iron is not the answer. Iron without knowing why you are low can be the wrong move.

Frequently asked questions

Is a ferritin of 35 low?
It sits above Awanui's cut-off of 30, so it is generally passed as normal. It is well below the 80 to 100 I work to. Whether it matters for you depends on your symptoms, the rest of the panel and why it is where it is. A result under 30 is low, and worth taking to your doctor.

Can ferritin be normal and I still feel exhausted?
Yes. A result of 35 can be called normal while you feel exhausted, because the cut-off is there to catch iron deficiency, not to tell you whether you are functioning well.

Does a high ferritin mean I have plenty of iron?
Not necessarily. Ferritin rises with inflammation, so a high result has to be read alongside the rest of the iron panel. Consistently high iron is worth reviewing with your doctor.

Should I take an iron supplement if my ferritin is low?
That is a question to work through with a practitioner who knows your history. The reason your ferritin is low matters more than the number, and iron without knowing why can be the wrong move.

See where your own numbers sit

The Full Picture Handbook covers every marker in the iron panel, with the standard range and the range I work to side by side. The Results Decoder plots your own numbers against them. Both are free, along with a free workshop on what standard testing misses.

Get the handbook and Decoder at naturalist.co.nz/testing

This post is general education. It does not diagnose, and it does not replace medical care. Please do not start, stop or change any medication or supplement based on this post without talking to your doctor or health professional.