Low iron symptoms can look like being puffed by the first flight of stairs, losing your train of thought halfway through a sentence, and legs that won’t settle when you finally get into bed. And your blood count can still come back normal.
That’s because iron runs down in an order. Your stores go first, and your haemoglobin, the iron-carrying part of your red blood cells, drops last. So you can be low in iron for a long time before you’re anaemic, and a normal blood count doesn’t rule it out. It isn’t you being unfit, and you’re not making a fuss.
In Australia, more than one in five women have depleted iron stores. So the test I’d want is full iron studies, not a blood count or a ferritin on its own, read with your other bloods.
The short version
- Iron runs down in order: your stores first, your haemoglobin last. A normal blood count doesn’t rule out low iron.
- In a large US survey of women aged 20 to 45, more of the women who were low in iron weren’t anaemic than were.
- Low iron can look like tiredness, breathlessness, restless legs, trouble concentrating and craving ice.
- Ferritin is your iron storage, but inflammation pushes it up, so full iron studies tell you more than ferritin alone.
- This week, find your last blood results and check whether ferritin was the only iron marker on them.
What low iron symptoms usually look like
Iron’s main job is carrying oxygen. It sits in your red blood cells and gets that oxygen from your lungs to every part of you, including the muscles you’re asking to get you up the stairs.
When iron runs low, the signs tend to arrive slowly, and they’re easy to put down to a busy year. These are the ones a 2025 review of iron deficiency in adults lists, in plain words:
- Tiredness that a weekend of sleep doesn’t touch.
- Getting puffed doing things that used to be easy, like stairs, a hill or your usual workout.
- Feeling lightheaded.
- Trouble concentrating, irritability, and a low mood that doesn’t feel like you.
- Restless legs: an urge to move them in the evening or in bed. The review puts it at 32 to 40% of people with iron deficiency.
- Craving things that aren’t food, most often ice. That’s called pica, and the same review puts it at 40 to 50%.
The ice one surprises people. At one US clinic, in the records of 262 adults low enough in iron to need it through a drip, 45% reported pica, and for 87% of them it was ice.
Periods belong on this list too, though usually as the reason rather than the symptom. If your periods have got heavier or longer, they can take more iron out each month than your food is putting back.
A lot of this overlaps with an underactive thyroid, low B12 and broken sleep. So iron is one thing we check, beside the rest, rather than the answer to everything.
Why your blood count can be normal while your iron runs low
Your body keeps a store of iron for the days you need more than you eat. That store is ferritin, and transferrin is the protein that carries iron around your body to where it’s needed.
When more iron goes out than comes in, through periods, a pregnancy, a diet light on iron or a gut that isn’t absorbing it well, your body draws on the store. Your red blood cells keep getting made as normal while there’s iron in the store to make them with.
Only when the store is nearly empty does your haemoglobin start to fall. That’s iron deficiency anaemia, and it’s the stage a full blood count picks up. Everything before that stage is iron deficiency without anaemia, and the 2025 review is clear that people can have symptoms at that stage too.
So “your blood count’s normal” answers one question: are you anaemic? It doesn’t answer whether your stores are running low. (If you’ve been told all your bloods are normal and you’re still exhausted, I’ve written more about that in why you can be tired with normal bloods.)
How many women are low in iron without being anaemic
A study published this year looked at 8,200 non-pregnant women aged 20 to 45 in the US national health survey, between 1999 and 2023, and counted how many were iron deficient and how many were also anaemic.
They used a strict line for iron deficiency, a ferritin under 15. Across all those years, 17.3% of the women were iron deficient. Only 6.2% were iron deficient and anaemic. The other 11.1% were low in iron with a haemoglobin that would have come back normal.
This is US data, and a ferritin of 15 is a lower line than the one commonly used here. Using the Australian line of 30, a 2024 review in the Medical Journal of Australia puts depleted iron stores at 22.3% of Australian women.
Why I ask for full iron studies, not just ferritin
Ferritin is the most useful single marker of your iron stores, and a low ferritin is a reliable sign they’re running down. The catch is the other direction.
Ferritin also rises when there’s inflammation in your body, so it can read normal, or even high, in someone who’s actually short on iron. The same 2024 review lists inflammation, carrying extra weight, fatty liver and other chronic conditions as things that can do this, and says that with inflammation, a ferritin under 70 may still mean iron deficiency.
Full iron studies are one blood test that includes your ferritin, the iron in your blood, your transferrin, and your transferrin saturation, which shows how much of that transferrin is actually carrying iron. A saturation under 20% means not enough iron is getting to where it’s needed, even when the ferritin looks fine.
If you already have a ferritin number in front of you, our ferritin checker shows where it sits against each of these cut-offs.
What I ask for in clinic. I ask for iron studies, not just ferritin, so we can see whether all of your iron markers are sitting in the optimal range. Ferritin can be falsely high if there’s inflammation in the body, so the full iron panel, including transferrin, the protein that carries iron around your body, gives us the true reading.
Where low iron usually comes from
Then there’s the bit that stops it coming straight back: why. These are the common reasons the review lists:
Your periods. Menstrual bleeding is one of the most common causes of low iron in women. Heavier periods than you used to have are worth mentioning to your GP in their own right.
What you’re eating. Not getting enough iron from food is a common cause on its own.
How well your gut absorbs it. Coeliac disease, an inflamed or thinned stomach lining, and weight-loss surgery can all mean less iron gets in, however well you eat.
Medicines and inflammation. Regular anti-inflammatory painkillers are a known risk factor, and so are inflammatory bowel disease and other long-term inflammatory conditions. Please don’t stop anything you’ve been prescribed. Bring the list, and we’ll go through it alongside your GP.
Bleeding from the gut. This is the one that needs a doctor before anything else. Blood in your poo, black stools, low iron once your periods have stopped, or low iron with no obvious cause like heavy periods all go straight to your GP. In men and in women after menopause, the 2024 Australian review notes that a bleed in the gut turns up in about two-thirds of those with iron deficiency anaemia.
What to check first, and in what order
Iron is rarely the only thing I look at. The basic foundations I’d want are a full blood examination, iron studies, B12, folate, a full thyroid panel with antibodies, vitamin D, fasting homocysteine, liver enzymes and electrolytes, fasting insulin and fasting blood glucose, and serum zinc.
If your results come back as normal and you still don’t feel right, our Blood Test Analysis is fifteen minutes, one-on-one, going through the results you already have and showing you where each number is sitting, not just whether it’s in range. It’s $79. If your bloods are more than six months old or missing pieces, we can give you a list to take to your GP (and try and get bulk billed), or write a private referral slip you can take to the lab directly.
This is the order we work through with you:
- Anything that needs a doctor first. Anaemia on your blood count, low iron after menopause or with no obvious cause, periods heavy enough to flood or soak through, pregnancy, chest pain, fainting, or symptoms getting worse quickly.
- The full iron studies, read properly. Ferritin, iron, transferrin and saturation together, against where they should sit for you, and with any inflammation taken into account.
- Why it’s low. Periods, food, absorption, medicines and life stage, because that’s what keeps it from coming straight back.
- Recheck. Iron stores take time to rebuild, so a repeat test with your GP is how you know it’s working.
One thing please don’t do: start iron on a hunch. Haemochromatosis, an inherited condition where your body stores too much iron, affects an estimated one in 200 people of northern European background, and its early signs include tiredness, weakness and sore joints. Test first, so you know which direction you’re in.
What to do this week
- Find your last blood results, or ask your GP’s reception for a copy, and look at the iron section. Is ferritin the only iron marker on it, or are iron, transferrin and saturation there too? Write the numbers down.
- Look back over your last three periods. Write down how many days each one lasted, how many of those were heavy, and whether that’s changed in the past year or two.
- Write down which of the symptoms above you have, and roughly when each one started.
- Book in with your GP and ask whether full iron studies and the basic foundations above make sense for you.
If you’re still not sure whether this is you, ask yourself:
- Has anything more than ferritin ever been tested?
- Do I get puffed doing things that used to be easy?
- Have my periods got heavier or longer?
- Do my legs feel restless at night?
- Have I been told I’m fine more than once this year, and still don’t feel it?
And if you’ve been crunching the ice out of every drink lately, you’re not being weird! It’s worth mentioning to your GP.
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Common questions
Can you have low iron with normal haemoglobin?
Yes. Iron deficiency usually starts with your stores running down while your haemoglobin stays normal, and anaemia only shows up once the stores are nearly empty. In a large US survey of women aged 20 to 45, more of the women who were iron deficient had a normal haemoglobin than a low one. Iron studies, which include ferritin, are the test that picks up the earlier stage.
Is it possible to have normal iron levels but low ferritin levels?
Yes. The iron reading on a blood test is the iron in your blood at the moment the sample was taken, while ferritin reflects how much you have in storage. A normal iron with a low ferritin usually means your stores are running low. That’s why the markers in your iron studies are read together, not one at a time.
What happens if your iron is low for too long?
Iron deficiency that isn’t picked up and sorted out can progress to iron deficiency anaemia, where your haemoglobin drops. Symptoms like tiredness, breathlessness and trouble concentrating can get worse as it does. If your symptoms are getting worse, or you notice chest pain, fainting or bleeding from the gut, see your GP promptly.
How do you get your iron levels up?
Start by finding out why it’s low, because that decides whether it comes back. Treatment is usually iron by mouth first, with an iron infusion for some people, and that’s guided by your GP. Food matters alongside it. Please don’t start iron without a blood test first: an inherited condition called haemochromatosis makes the body store too much iron, and its early signs can look like low iron.
Sources
Every study and number in this post comes from one of these.
- Xiao MZX and colleagues. Trends in anemia and iron deficiency among nonpregnant U.S. women of reproductive age, 1999 to 2023. Obstetrics and Gynecology, 2026. NHANES, 8,200 women aged 20 to 45.
- Auerbach M, DeLoughery TG, Tirnauer JS. Iron deficiency in adults: a review. JAMA, 2025.
- Zhang GD and colleagues. …and management of iron deficiency in the era of routine ferritin testing of blood donors by Australian Red Cross Lifeblood. Medical Journal of Australia, 2024.
- Barton JC and colleagues. Pica associated with iron deficiency or depletion: clinical and laboratory correlates in 262 non-pregnant adult outpatients. BMC Blood Disorders, 2010.
- Healthdirect. Haemochromatosis.
Important: This article is general information written by a clinical nutritionist. It's not medical advice and doesn't replace care from your GP or another qualified health professional. Functional testing is not diagnostic and doesn't diagnose, treat, cure or prevent any condition, and results are best interpreted alongside your symptoms, history, medications and supplements.
Reviewed by Georgina Waugh
Clinical Nutritionist, BHSc Nutritional Medicine
Last updated: 9 November 2026
Sources reviewed: A 2026 study of anaemia and iron deficiency in US women, a 2025 review of iron deficiency in adults, a 2024 Australian review of ferritin testing, a clinic study of pica and low iron, and Australian health pages.