Iron deficiency in women can cause fatigue, brain fog, hair loss, shortness of breath, and reduced exercise tolerance, even when a blood count does not show anemia. A ferritin blood test helps evaluate stored iron, while a CBC checks for anemia. Understanding that difference is an important part of knowing what to ask when you do not feel like yourself.
Maybe you are exhausted despite going about your usual routine. Maybe you cannot concentrate, your hair is falling out, or workouts that once felt manageable suddenly leave you drained. In her video on iron deficiency, Dr. Natalie Crawford explains why these symptoms deserve attention and why checking only for anemia may leave part of the picture unexplored.
The goal is not simply to find a low number and take more iron. It is to understand whether your iron stores are low, why that is happening, and whether treatment is helping replenish them.
IN THIS VIDEO:
00:00 Iron deficiency in women
00:45 What does iron do in the body?
02:56 What are the symptoms of iron deficiency?
03:42 Ferritin blood test: What do your levels mean?
05:26 How does inflammation affect ferritin levels?
06:39 What blood tests check for iron deficiency?
07:38 What causes low iron in women?
09:26 What foods are high in iron?
10:10 How to take iron supplements
10:46 When do you need iron infusions?
11:37 Iron deficiency vs. anemia: What's the difference?
Iron deficiency and anemia are not the same thing
If there is one thing I want you to remember, it is this: you can have iron deficiency without being anemic.
A CBC, or complete blood count, gives us information about hemoglobin and hematocrit. It helps us check for anemia, but it does not tell us everything we need to know about iron.
Iron deficiency can contribute to anemia, but they are not the same diagnosis. If the only blood test you have had is a CBC, a result that does not show anemia does not rule out low iron stores.
That is why ferritin matters. It gives us information about your stored iron so we can identify deficiency rather than waiting until those stores are fully depleted.
What does iron do in your body?
Iron is much more than a component of hemoglobin or a part of your blood. Your body needs it for functions that affect how you feel every day.
Oxygen transport
Iron helps carry oxygen to your tissues. When iron is low, your body may not get oxygen where it needs to go as effectively. This can contribute to fatigue and shortness of breath.
Cellular energy
Your mitochondria, often called the powerhouses of your cells, need iron to function appropriately. This is another reason low iron can leave you feeling tired.
Brain function
Iron is important for neurotransmitter production and normal brain communication. These are the signals your brain sends to the rest of your body. Low iron can affect that communication and contribute to brain fog or difficulty concentrating.
Immune function
Many of your immune cells need iron. Low iron can contribute to an immune system that does not function as well.
If you feel like you are always getting sick, even when everyone around you seems fine, iron deficiency is one of the things I think about.
Muscle function and exercise capacity
Iron affects your exercise capacity and how quickly you become fatigued.
I experienced this before my celiac diagnosis, when I was significantly iron deficient. I remember thinking, “I can’t do what I used to be able to do.” I could not run as far or lift as much. I was getting tired quickly, and it did not make sense because nothing else seemed to have changed.
A change in what your body can do is worth paying attention to, especially when it happens alongside other symptoms.
What are the symptoms of iron deficiency in women?
Symptoms of iron deficiency can include:
Fatigue
Brain fog
Difficulty concentrating
Reduced exercise tolerance
Hair loss
Restless legs
Headaches
Dizziness
Shortness of breath
A racing heart
Cravings for things that are not food, including chewing ice
Restless legs can feel like you cannot keep your legs still. Sometimes the sensation can feel almost like numbness.
Another symptom I find particularly interesting is pica, which means craving things that are not food. A strong desire to chew ice can be a sign of iron deficiency. I do not mean simply enjoying ice in your drink. I mean wanting to chew it.
These are symptoms to bring up with your physician, even if you have previously been told that your blood count is normal.
What does a ferritin blood test tell you?
Ferritin gives us information about your stored iron. A low ferritin level is one of the first signs that your iron is low.
Think about the money you have available versus the money in your savings account. They are different, but both tell you something important about your resources. We do not want to wait until your reserves are fully depleted before recognizing a problem.
Ferritin is the most useful single marker for evaluating iron stores, but we also need to understand your history and whether inflammation could be affecting the result.
Why a ferritin result labeled normal may deserve a closer look
Laboratory reference ranges reflect a population. That does not necessarily mean every result within that range is optimal for your circumstances.
This can be confusing when you are looking at your own results. A number may not be flagged as abnormal, so it is easy to assume there is nothing more to discuss.
An older ferritin threshold of 15 nanograms per milliliter could allow low iron stores to be missed. The minimum threshold I want you to understand is 30 nanograms per milliliter for adults, including during pregnancy.
For heavy menstrual bleeding or pregnancy planning, I look for a higher threshold of at least 50 nanograms per milliliter. Pregnancy requires a lot of iron, and heavy menstrual bleeding puts you at risk of continued iron loss.
The important point is that your result needs to be interpreted in the context of your history. An unflagged number does not always answer the whole question.
How inflammation affects ferritin levels
Inflammation changes how we interpret ferritin.
Ferritin is an acute phase reactant, which means it can rise during significant inflammation. In that situation, an elevated result can reflect an inflammatory response rather than adequate iron stores.
If you have an autoimmune condition, are ill when your blood is drawn, or have another reason for inflammation, we need to look at the result differently.
For adults with inflammation, I look for a ferritin level of at least 100 nanograms per milliliter. Another option is to check transferrin saturation. A result below 20 percent is a sign of iron deficiency.
As someone with an autoimmune disease, I know how important this distinction is. In some of my patients with autoimmune conditions, we make sure testing is not happening during a flare, or we repeat it when they are feeling better.
A higher ferritin result does not automatically mean your iron stores are adequate if inflammation is influencing the number.
What blood tests check for iron deficiency?
Different blood tests answer different questions. Understanding what each one tells us can help you understand your evaluation.
CBC
A CBC checks hemoglobin and hematocrit and helps us evaluate anemia. It does not, by itself, rule out iron deficiency.
Ferritin
Ferritin tells us about stored iron. It is the most useful single marker for identifying low iron stores.
Transferrin saturation
Transferrin saturation tells us about how much iron is available and circulating. It can be especially helpful when inflammation makes ferritin more difficult to interpret.
High sensitivity CRP
CRP is a marker of inflammation. If we are unsure whether inflammation is present, we may check a high sensitivity CRP alongside ferritin.
If CRP is elevated, we know inflammation needs to be considered when interpreting the ferritin result.
The goal is not simply to order more tests. It is to understand whether we have checked for anemia, evaluated iron stores, and accounted for anything that could affect those results.
What causes low iron in women?
Once we identify iron deficiency, the next question is why.
We need to understand whether you are losing iron, not getting enough through food, having difficulty absorbing it, or experiencing a combination of factors. If there is an underlying cause that needs treatment, we want to address it.
Heavy menstrual bleeding
Heavy menstrual blood loss is one of the common reasons for iron deficiency.
It can be related to uterine polyps, uterine fibroids, adenomyosis, bleeding disorders such as von Willebrand disease, or abnormal ovulation. Abnormal ovulation can sometimes lead to more sporadic or increased blood loss.
You can also become so accustomed to heavy bleeding that you think it is normal. I have a friend who told me she always bleeds through her clothes during her period. That is not normal, and it makes me concerned about her risk of iron deficiency.
Your bleeding pattern matters. Replacing iron is only part of the conversation if you are continuing to lose a significant amount of blood each month.
Pregnancy and postpartum
Pregnancy requires iron as your blood volume expands and your body supports a developing baby.
Many women enter pregnancy with low iron stores, and those stores become depleted even further. Then blood loss during delivery can add to that depletion.
If you are pregnant or postpartum and find out you are iron deficient, these demands and losses may help explain why. This is one reason I want you to understand your iron stores before and during these stages.
Low iron intake and difficulty absorbing iron
Nutritional and gastrointestinal causes also matter.
Low intake of foods containing iron can contribute, but so can celiac disease, other conditions that affect absorption, and a history of bariatric surgery.
I have celiac disease, so I know I am at risk for iron deficiency. It is not always just a question of how much iron you eat. Your body also needs to be able to absorb it.
Gastrointestinal blood loss
We also need to consider blood loss from the gastrointestinal tract.
Inflammatory bowel disease, including Crohn’s disease and ulcerative colitis, is part of this discussion. A family history of colon cancer is also important information to share with your physician.
We do not want to assume diet or menstrual bleeding explains every case without understanding the rest of your history.
Blood donation and endurance exercise
Recent or frequent blood donation can contribute to low iron. Endurance athletes also often experience iron deficiency.
These details help us understand what might be depleting your stores and whether there is something specific we need to address.
What foods contain iron?
Improving dietary sources of iron is one part of treatment.
Animal sources include red meat, poultry, fish, and shellfish. Plant sources include lentils, beans, tofu, spinach, and cereals fortified with iron.
Vitamin C is also important because it supports iron absorption.
Food is one part of the bigger picture. We still need to understand why your iron is low, whether supplementation is needed, and whether your stores are improving.
How are oral iron supplements used?
Treatment is not about finding the highest dose of iron you can take.
With oral supplementation, I do not recommend taking iron more than once a day. I find that taking it every other day can improve tolerance and absorption.
Vitamin C matters here, too. Some supplements pair iron with vitamin C.
One product I personally like is MegaFood’s Blood Builder. This is not sponsored. I have found it well tolerated and helpful both for myself and for some of my patients when iron deficient. Whatever product you use, we still need to monitor your response.
Side effects and follow up
Constipation and gastrointestinal discomfort can occur with oral iron. Make sure you are drinking plenty of water, and discuss tolerance with your physician.
We also need a plan to check whether the treatment is working. Taking a supplement does not automatically tell us that your iron stores have recovered.
Following ferritin helps us see whether those stores are being replenished.
When might you need iron infusions?
Sometimes oral iron is not enough, and IV iron, also called an iron infusion, may be needed.
This may be considered when:
Oral iron cannot be tolerated
Iron deficiency persists despite treatment
You are not absorbing iron adequately
You are losing iron faster than you can replace it
This decision needs to be guided by your physician.
We also need a clear follow up plan so we know when we are checking your response and whether you are recovering from iron deficiency. The goal is to address the cause, improve intake and absorption, and make sure your iron stores are actually improving.
What to ask your physician about possible iron deficiency
I want you to feel comfortable asking what has been checked and what your results mean for you.
If you have symptoms or a history that raises concern, these questions can help guide that conversation:
Have we evaluated my iron stores, or have we only checked a CBC for anemia?
How should my ferritin result be interpreted given my symptoms and medical history?
Could heavy menstrual bleeding, pregnancy, postpartum changes, diet, blood donation, or difficulty absorbing iron be contributing?
If I have inflammation or an autoimmune condition, would transferrin saturation or CRP help clarify the result?
If I need treatment, when will we check whether my iron stores are improving?
Knowing your history and understanding the purpose of each test can help you advocate for your care.
Frequently asked questions about iron deficiency in women
Can you have iron deficiency without anemia?
Yes. Iron deficiency and anemia are not the same thing. Iron deficiency can contribute to anemia, but you can have low iron stores without being anemic.
Does a normal CBC rule out iron deficiency?
No. A CBC helps check for anemia using information such as hemoglobin and hematocrit. Ferritin gives us different information about stored iron.
Can iron deficiency cause brain fog and hair loss?
Yes, brain fog, difficulty concentrating, and hair loss can occur with iron deficiency. Other symptoms can include fatigue, reduced exercise tolerance, restless legs, headaches, dizziness, shortness of breath, and a racing heart.
Can chewing ice be a sign of low iron?
A strong desire to chew ice can be a sign of iron deficiency. It is different from simply enjoying a cold drink or having ice in your glass.
Why can ferritin be misleading when you have inflammation?
Ferritin can rise as part of an inflammatory response, so an elevated result may not reflect adequate iron stores. We need to interpret it differently when inflammation is present and may use transferrin saturation to get more information.
Can heavy periods cause iron deficiency?
Heavy menstrual blood loss can contribute to iron deficiency. We need to understand and address the bleeding, not just replace the iron you are losing.
Why might oral iron be taken every other day?
Taking oral iron every other day can improve tolerance and absorption. Vitamin C, side effects, and follow up testing are also important parts of the plan.
When are iron infusions considered?
Iron infusions may be considered when oral iron cannot be tolerated, deficiency persists despite treatment, absorption is inadequate, or iron losses exceed what can be replaced. Your physician should guide this decision.
The bottom line
Iron deficiency is not only about anemia. It can affect your energy, concentration, hair, exercise tolerance, and how you feel in everyday life.
If the only test you have had is a CBC, you may not yet have the full picture of your iron stores. Ask about ferritin and how your result should be interpreted given your own history, including heavy menstrual bleeding, pregnancy planning, pregnancy, postpartum changes, or inflammation.
Treatment is not simply about taking more iron. We need to know why it is low, improve dietary sources and absorption, choose an appropriate treatment plan, and follow up to make sure your stores are recovering.
Your symptoms deserve to be taken seriously. Know your history, ask questions, and advocate for your care.