Iron Deficiency in Women: Signs and Testing

Iron deficiency can exist before a blood count shows anaemia. That distinction matters because a person may have depleted iron stores, fatigue or reduced exercise tolerance while haemoglobin remains within the laboratory range.

Symptoms alone cannot diagnose iron deficiency. Testing should confirm it and help identify why it developed.

Possible symptoms

Iron deficiency may contribute to:

• persistent tiredness or reduced stamina
• breathlessness or a racing heartbeat with exertion
• headaches, dizziness or difficulty concentrating
• restless legs
• hair shedding or brittle nails
• cravings for non-food substances such as ice

These symptoms are not specific. Thyroid disease, sleep problems, depression, infection, pregnancy and other conditions can look similar.

Heavy periods are a common cause

Regular menstrual blood loss can gradually deplete iron. Bleeding may be considered heavy when it floods through protection, requires changing products during the night, includes large clots, lasts longer than about seven days or interferes with normal activity.

Heavy bleeding deserves evaluation rather than iron replacement alone. Fibroids, adenomyosis, bleeding disorders, medication effects and other gynaecological causes may need treatment.

Which tests are useful?

A complete blood count checks haemoglobin and red-cell features. Ferritin is the main marker of stored iron, and transferrin saturation can add information.

Ferritin interpretation is not one-size-fits-all. A very low value strongly supports iron deficiency, but ferritin rises during inflammation and may look normal despite limited available iron. Pregnancy and chronic disease also change interpretation. This is why clinicians review symptoms, blood count, ferritin, transferrin saturation and the clinical context together.

Normal haemoglobin does not rule out iron deficiency. Conversely, fatigue with a normal ferritin should not automatically be treated with iron.

Finding the cause

Assessment may consider:

• menstrual and other bleeding
• pregnancy or recent birth
• dietary intake
• gastrointestinal blood loss
• coeliac disease, inflammatory bowel disease or other malabsorption
• blood donation, surgery or medication effects

New iron deficiency after menopause, or in someone without menstrual loss, often needs gastrointestinal evaluation.

Treatment is more than buying a supplement

Oral iron is commonly first-line, but products differ and side effects such as nausea or constipation can affect adherence. Intravenous iron may be considered when oral treatment is not tolerated, is ineffective, cannot be absorbed or when losses are ongoing.

Do not take high-dose iron indefinitely without testing. Excess iron can be harmful, and treatment without investigating the cause may delay diagnosis of continued bleeding.

Seek urgent care for chest pain, fainting, severe breathlessness, black stools, vomiting blood or heavy bleeding with weakness or dizziness.

Getting the right tests and treatment

Iron deficiency can occur with or without anaemia. The right approach confirms the diagnosis, investigates the reason and checks that iron stores recover—not just that symptoms temporarily improve.

This article provides general education and does not replace blood testing or individualized treatment.

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References

1. Auerbach M, Deloughery TG, Tirnauer JS. “Iron Deficiency in Adults: A Review.” JAMA (2025)
2. Munro MG, et al. “The Relationship between Heavy Menstrual Bleeding, Iron Deficiency, and Iron Deficiency Anemia.” American Journal of Obstetrics and Gynecology (2023)
3. Al-Naseem A, et al. “Iron deficiency without anaemia: a diagnosis that matters.” Clinical Medicine (2021)