Low Iron in Women: Could Low Ferritin Be Affecting Your Energy, Hormones and Fertility?

You're exhausted, but your bloodwork says everything is normal. Could it be your iron?

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If you've been feeling unusually tired, struggling to get through your workouts, experiencing brain fog or noticing that your energy just isn't what it used to be, iron might be worth a closer look.

Iron deficiency is one of the most common nutritional deficiencies worldwide, and women are particularly susceptible due to menstruation, pregnancy, postpartum recovery and increased iron demands throughout different stages of life.

But here's something many women don't realize: you can have low iron stores without being anemic.

In other words, your hemoglobin can fall within the normal laboratory reference range while your ferritin (your body's stored iron) is already depleted.

At Somewhere Health, we believe understanding your bloodwork is an important part of understanding your health. Let's look at why iron matters beyond simply preventing anemia, how it connects to women's hormonal and reproductive health, and which blood tests can help give you a clearer picture.

1. Low iron and fatigue: Why you might feel exhausted even without anemia

Iron plays an important role in several processes throughout the body, including:

• Producing hemoglobin, which carries oxygen in your red blood cells.
• Supporting cellular energy production and mitochondrial function.
• Supporting normal muscle function and oxygen utilization.
• Contributing to cognitive function and neurological health.

When iron stores become depleted, these processes can become less efficient.

One of the biggest misconceptions about iron deficiency is that you need to be anemic to experience symptoms.

This isn't necessarily true.

A 2018 systematic review and meta-analysis published in BMJ Open evaluated 18 clinical trials involving 1,170 adults with iron deficiency but no anemia.

Researchers found that iron supplementation was associated with a reduction in self-reported fatigue, even when participants did not have anemia. Interestingly, improvements in objective measures of physical performance were not demonstrated.

This is important because it highlights the distinction between iron deficiency and iron deficiency anemia.

Common symptoms associated with low iron include:

• Persistent fatigue or low energy
• Brain fog or difficulty concentrating
• Reduced exercise tolerance
• Feeling weak or physically depleted
• Hair shedding
• Restless legs
• Headaches
• Shortness of breath, particularly with exertion
• Feeling unusually cold

Not everyone with low ferritin will experience symptoms, and these symptoms can have many other causes. However, if you're experiencing ongoing fatigue, iron status is one piece of the puzzle worth investigating.

2. Low iron and women's hormones: What's the connection?

Iron isn't a hormone, and taking an iron supplement isn't going to balance estrogen or progesterone.

However, iron plays an important supporting role in several physiological processes that influence women's hormonal health.

There are three areas worth understanding.

Menstrual health and iron depletion

Your menstrual cycle is one of the most common reasons women develop iron deficiency.

Every month, blood loss contributes to iron loss. Women experiencing heavy menstrual bleeding may be at an even greater risk of developing depleted iron stores over time.

This can create a frustrating cycle:

1. Heavy periods contribute to ongoing iron loss.
2. Iron stores gradually become depleted.
3. Fatigue, weakness and reduced exercise tolerance may develop.
4. The underlying menstrual bleeding continues, making it difficult to replenish iron stores.

If you experience heavy periods, flooding, frequent pad or tampon changes, large clots or periods lasting longer than seven days, it's worth discussing this with your healthcare provider.

Rather than simply replacing iron, it's important to investigate why you're losing it in the first place.

Iron and thyroid function

Here's another interesting connection.

Iron is required for the activity of thyroid peroxidase (TPO), an enzyme involved in thyroid hormone synthesis.

This means iron deficiency may interfere with normal thyroid hormone production.

Thyroid hormones influence metabolism, body temperature, energy levels, menstrual regularity and reproductive function.

However, this doesn't mean that everyone with low iron has a thyroid problem, or that iron supplementation will correct hypothyroidism.

If you're experiencing fatigue, hair loss, feeling cold, constipation or menstrual changes, it may be worth assessing both iron status and thyroid function rather than looking at one nutrient in isolation.

Iron and reproductive health

Iron is essential for normal cellular function, oxygen delivery and healthy tissue development.

Because reproductive health involves rapidly dividing cells and significant physiological demands during pregnancy, maintaining adequate iron stores is important when preparing for pregnancy.

Iron deficiency is not an established standalone cause of hormonal imbalance or infertility. However, ensuring iron sufficiency is an important part of supporting overall preconception health.

3. Low iron and trying to conceive: Why preconception iron status matters

If you're trying to conceive, iron is one nutrient worth paying attention to before you see a positive pregnancy test.

Iron requirements increase during pregnancy to support maternal blood volume expansion, placental development and the growing baby's needs.

Starting pregnancy with depleted iron stores can make it more challenging to meet these increased demands.

But is there a connection between iron deficiency and fertility itself?

Emerging research suggests there may be.

A 2025 study published in Acta Obstetricia et Gynecologica Scandinavica investigated the relationship between iron deficiency and fertility outcomes.

The retrospective observational study followed 292 women with infertility and low ferritin levels (30 µg/L or lower) who received intravenous iron treatment.

Researchers observed that:

• The proportion of women who conceived increased from 65% before treatment to 77% after treatment.
• Live birth rates increased from 26% to 51%.
• Miscarriage rates decreased from 28% to 13%.

These findings are interesting, particularly for women navigating fertility challenges.

However, there is an important distinction: this was an observational study comparing outcomes before and after treatment. It does not establish that iron supplementation caused the improvements, nor does it demonstrate that iron treatment improves fertility in women who are not iron deficient.

We need more prospective clinical trials to understand this relationship.

So, what does this mean if you're trying to conceive?

It means iron status deserves a place in the broader preconception conversation, particularly if you have:

• Heavy or prolonged menstrual cycles
• A history of low ferritin or iron deficiency anemia
• Persistent fatigue
• A predominantly plant-based diet
• A history of pregnancy or postpartum blood loss
• Difficulty maintaining adequate iron levels

Optimizing iron stores is one part of preparing your body for pregnancy, alongside assessing thyroid function, vitamin B12, vitamin D, menstrual health and other relevant factors.

4. Which blood tests should you ask for?

One of the most important things to understand is that a CBC alone may not tell you the whole story.

A complete blood count (CBC) evaluates your red blood cells, hemoglobin and other blood cell markers. It can help identify anemia, but it does not directly measure your body's stored iron.

If you're investigating possible iron deficiency, consider discussing the following tests with your healthcare provider.

- Complete Blood Count (CBC): Evaluates red blood cells, hemoglobin, hematocrit and other blood cell markers to help identify anemia.

- Hemoglobin (Hb): Measures the oxygen-carrying protein in red blood cells. Low levels may indicate anemia.

- Hematocrit (Hct): Measures the proportion of your blood made up of red blood cells.

- Mean Corpuscular Volume (MCV): Measures the average size of your red blood cells. Low MCV can be associated with iron deficiency.

- Mean Corpuscular Hemoglobin (MCH): Measures the average amount of hemoglobin in each red blood cell. Low levels can be associated with iron deficiency.

- Ferritin: Reflects your body's stored iron and is one of the most important markers when assessing iron deficiency. Low ferritin can occur even when hemoglobin is normal.

- Serum Iron: Measures the amount of circulating iron in your blood.

- Total Iron Binding Capacity (TIBC): Measures your blood's capacity to bind iron and helps assess iron availability.

- Transferrin Saturation (TSAT): Measures the percentage of transferrin carrying iron and helps provide a more complete picture of iron status.

A note: A CBC alone may not identify early iron deficiency. Including ferritin, and sometimes a full iron panel, can provide a more comprehensive assessment.

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What is a normal ferritin level?

Ferritin is one of the most useful markers when investigating iron deficiency.

In Ontario, updated laboratory guidance from the Ontario Association of Medical Laboratories uses a clinical decision limit of 30 µg/L for adults to help identify iron deficiency.

This is important because laboratory reference ranges can sometimes be misleading when interpreting iron status.

A ferritin result within the laboratory's reference range does not automatically mean iron stores are optimal for every individual.

The result should be interpreted alongside symptoms, menstrual history, pregnancy status, inflammation and other laboratory findings.

Ferritin is also an acute-phase reactant, meaning it can increase with inflammation or infection. In certain circumstances, additional iron markers may be needed to understand the full picture.

The goal isn't to chase an arbitrary ferritin number. It's to identify deficiency, understand the underlying cause and determine an appropriate treatment plan.

5. How can you naturally support healthy iron levels?

If your iron stores are low, nutrition can be an important part of your plan.

There are two main types of dietary iron:

Heme iron: Found in animal-based foods and generally more readily absorbed.

Examples include:

• Beef
• Lamb
• Chicken
• Turkey
• Fish and shellfish

Non-heme iron: Found in plant-based foods. Absorption is generally lower and more variable.

Examples include:

• Lentils
• Chickpeas
• Tofu
• Pumpkin seeds
• Spinach
• Fortified cereals
• Beans

Improve iron absorption with vitamin C

Pairing iron-rich foods with vitamin C can improve non-heme iron absorption.

Try:

• Lentils with bell peppers.
• Spinach with strawberries.
• Chickpeas with lemon juice.
• Tofu with broccoli.
• Iron-fortified oats with berries.

Be mindful of coffee and tea

Coffee and tea contain polyphenols that can reduce iron absorption when consumed alongside iron-rich meals.

If you're working on improving your iron status, consider separating coffee and tea from iron-rich meals or prescribed iron supplements.

Should you take an iron supplement?

Not everyone needs an iron supplement.

If bloodwork confirms iron deficiency, your healthcare provider can help determine whether dietary changes, oral supplementation or, in certain circumstances, intravenous iron are appropriate.

The right approach depends on your ferritin, hemoglobin, symptoms, underlying cause and tolerance.

Taking too much iron can cause gastrointestinal side effects and potentially harmful iron accumulation. Supplementation should be guided by appropriate testing and follow-up rather than started simply because you're feeling tired.

6. When should you investigate your iron levels?

You don't have to wait until you're completely exhausted to investigate your iron status.

It may be worth discussing testing with your healthcare provider if you're:

• Experiencing persistent fatigue or brain fog.
• Having heavy or prolonged periods.
• Trying to conceive or preparing for pregnancy.
• Recovering from pregnancy or postpartum blood loss.
• Experiencing unexplained hair shedding.
• Following a vegetarian or vegan diet.
• Training regularly and noticing a decline in exercise tolerance.
• Managing a history of iron deficiency.

It's also important to investigate the reason for iron deficiency. Heavy menstrual bleeding, inadequate dietary intake, gastrointestinal blood loss and impaired absorption can all contribute.

Simply taking an iron supplement without addressing the underlying cause may not resolve the problem.

The Somewhere Health takeaway

Iron is about so much more than preventing anemia.

For women, understanding iron status can be an important part of investigating persistent fatigue, menstrual health, thyroid function and preconception wellness.

And remember: normal hemoglobin doesn't necessarily mean your iron stores are adequate.

If you've been feeling unlike yourself, struggling with your energy or preparing for pregnancy, consider looking beyond the standard CBC and having a conversation about ferritin and your overall iron status.

At Somewhere Health, we take a whole-person approach to women's health. We look at your symptoms, health history, menstrual cycle and relevant bloodwork to help connect the dots and create a plan that makes sense for you.

You deserve to understand your bloodwork, not just be told that everything is normal.

Ready to take a closer look at your health?

Book a virtual naturopathic appointment with Somewhere Health and let's start connecting the dots.

About the author

Dr. Courtney Ranieri, ND is a board-licensed naturopathic doctor and the founder of Somewhere Health. She earned her Doctor of Naturopathic Medicine at the Canadian College of Naturopathic Medicine in Toronto and holds an Honours Bachelor of Science from the University of Western Ontario. Her clinical focus spans hormonal health, fertility, digestion, and women's health, with advanced training in pelvic floor therapy and integrative fertility care.

Book a visit with Dr. Courtney click here!

References & Further Reading

1. Houston BL, et al. (2018). Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials. BMJ Open, 8. https://doi.org/10.1136/bmjopen-2017-019240
2. Verdon F, et al. (2003). Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trial. BMJ, 326:1124. https://doi.org/10.1136/bmj.326.7399.1124
3. Tulenheimo-Silfvast A, et al. (2025). Association between iron deficiency and fertility. Acta Obstetricia et Gynecologica Scandinavica, 104(4):738–745. https://doi.org/10.1111/aogs.15046
4. Ontario Association of Medical Laboratories (2024). Guidelines for the Use of Laboratory Tests for Iron Deficiency.https://lmp.utoronto.ca/db-resource/guidelines-use-laboratory-tests-iron-deficiency
5. World Health Organization (2020). WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations. https://www.who.int/publications/i/item/9789240000124
6. American College of Obstetricians and Gynecologists (2021, reaffirmed 2024). Anemia in Pregnancy: Practice Bulletin No. 233. https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2021/08/anemia-in-pregnancy

Medical disclaimer: This article is for educational purposes and is not intended to replace individualized medical advice, diagnosis or treatment. Iron supplementation should be based on appropriate clinical assessment and laboratory testing.