A woman can have a clear depletion of her iron stores without a conventional blood count showing anaemia, as haemoglobin may remain within the normal range during the early stage of iron depletion. This stage may be accompanied by symptoms such as fatigue, poor concentration, hair loss and reduced exercise capacity, making ferritin testing important when deficiency is suspected rather than relying on haemoglobin measurement alone.
A review published by the Canadian Medical Association Journal in 2025 indicates that iron deficiency, whether or not it is accompanied by anaemia, is more common among women. The review considers a full blood count and ferritin measurement important initial tests when iron deficiency is suspected.
Causes of iron depletion in women
Ferritin is a protein inside cells that stores iron and releases it when the body needs it, so its level is used to estimate iron stores. Blood loss during menstruation, particularly when periods are heavy, is among the leading causes of iron depletion in women. The body’s need for this element also rises during pregnancy and after childbirth, while blood loss associated with delivery can further reduce iron stores.
Insufficient dietary iron or the digestive system’s inability to absorb it efficiently may worsen the problem. Nihal Ahmed, a professor of medical parasitology at Assiut University’s Faculty of Medicine, says that blood loss during menstruation, particularly in cases of heavy menstrual bleeding, is one of the main causes of iron deficiency in women.
She explains that pregnancy and breastfeeding increase the body’s requirements. During pregnancy, the needs of both the mother and the foetus must be met, while childbirth and the blood loss that accompanies it may further deplete iron stores.
The causes are not limited to blood loss or increased requirements. Nihal explains that impaired absorption may be associated with coeliac disease and some digestive disorders, and may also occur after bariatric surgery, including sleeve gastrectomy and gastric bypass. Causes also include diets low in iron, particularly when intake of animal sources containing haem iron is reduced. This is the form the body can absorb more efficiently.
Heavy periods hinder treatment of iron deficiency
The Canadian Medical Association Journal review confirms that addressing heavy menstrual bleeding is an essential part of treating iron deficiency in women. Continually giving iron without reducing the source of the loss may not resolve the problem sustainably; the deficiency may persist or return after blood and iron-store indicators improve temporarily.
Nihal explains that ferritin may fall while haemoglobin remains within the normal range because the body first begins using its iron reserves to maintain the production of red blood cells and haemoglobin. This is known as iron deficiency without anaemia and may go undiagnosed if assessment is limited to a blood count and does not include tests of iron stores.
At this early stage, symptoms that directly affect daily activity may appear, including fatigue, reduced ability to concentrate, hair loss and lower exercise capacity. The absence of anaemia on a conventional test does not necessarily mean that iron stores are adequate, as deficiency can precede a fall in haemoglobin and the clear emergence of anaemia.
However, interpreting a ferritin result requires consideration of overall health. According to the World Health Organisation, ferritin can rise during inflammation or infection despite an actual iron deficiency. The result should therefore not be read in isolation from other tests, indicators and the clinical condition assessed by a doctor.
Symptoms of deficiency may precede anaemia
Iron tablets are the first-line treatment in many cases of mild to moderate deficiency, according to Nihal. However, choosing them requires confirming that the digestive system can absorb iron, as well as that the patient can tolerate, continue and use the treatment as instructed.
The doctor determines the preparation, dose and method of administration according to each patient’s condition and tolerance. Digestive side effects may prevent some patients from continuing oral treatment, the most prominent of which are constipation, nausea and stomach upset.
Nihal says these symptoms may prompt some patients to stop treatment. The choice of iron preparations, doses and methods of use therefore needs to take individual tolerance into account rather than applying one approach to every case. Intravenous iron may be a suitable option when a patient cannot tolerate oral treatment, when iron absorption is poor, or when an adequate response has not been achieved after using tablets.
It may also be used in some cases requiring iron replacement within a shorter time, subject to medical assessment. The American Gastroenterological Association recommends intravenous iron when oral iron cannot be tolerated, when iron stores have not improved after an appropriate treatment trial, or when a condition makes absorption through the digestive system unlikely.
Nihal warns against giving intravenous iron without medical supervision or outside a facility equipped to deal with allergic reactions if they occur. According to the Canadian Medical Association Journal review, serious reactions associated with intravenous iron are rare, and true anaphylaxis after its administration is very rare.
Most acute reactions that may accompany the infusion are less serious, but this does not remove the need for medical supervision and readiness to manage them. A rise in ferritin or haemoglobin after treatment does not mean that the cause of the problem has ended.
Treating the cause of loss prevents recurrence
Nihal explains that iron may fall again if the factor that caused its loss continues. This may include ongoing bleeding caused by heavy periods or some uterine problems, failure to complete treatment until stores are restored, or an undiagnosed problem affecting iron absorption. The American Gastroenterological Association stresses that treating iron deficiency should not be limited to replacing the lost element; it should also include investigating and treating the underlying cause whenever possible.
This is particularly important in cases of chronic bleeding, coeliac disease and inflammatory bowel disease, as well as after some bariatric surgeries that may affect absorption. According to Nihal, the response to treatment is monitored through haemoglobin, ferritin and other iron indicators, although the timing of repeat tests varies according to the severity of the deficiency, the type of treatment used and the patient’s health.
The Canadian Medical Association Journal review states that, in patients whose haemoglobin is above 100 grams per litre, a full blood count and ferritin measurement can be repeated after about 2 to 3 months, while cases with lower haemoglobin may require earlier follow-up. Rebuilding iron stores with oral treatment may take about 3 to 6 months.
After intravenous iron is given, ferritin should not be measured during the first four weeks because its level may appear temporarily elevated and produce a misleading result. Nihal stresses that treatment success is not measured by a rise in a single figure, but by improved haemoglobin, restored iron stores and reduced symptoms, alongside treatment of the original cause of the deficiency.
Regarding preparation for tests, Ahmed Abdel-Lah Tawfiq, director of a medical testing laboratory in Egypt, advises following the doctor’s and laboratory’s instructions before undergoing iron tests. He also urges patients to tell the laboratory about all supplements and medicines they use, particularly preparations containing iron, as these may affect some measurements.
Tawfiq explains that the assessment may include a blood count, haemoglobin and ferritin, as well as blood iron levels, total iron-binding capacity and transferrin saturation when needed. He stresses that no single result should be relied on in isolation from the other tests, as considering the indicators together helps provide a more accurate picture of the body’s iron status.
Preparation varies according to the type of test required. Ferritin measurement alone is not significantly affected by recent food intake, whereas blood iron measurements can be affected by the time the sample is taken, food and supplements.
Laboratories recommend that iron-test samples be taken in the morning, preferably after fasting for 8 hours, while avoiding iron-containing supplements for 24 hours before sampling, in accordance with the doctor’s and laboratory’s instructions and without stopping any treatment independently. Diet helps support iron stores, and the element exists in two main forms.
The first is haem iron, found in meat, poultry and seafood, which has a higher absorption rate. Non-haem iron is found in pulses, vegetables, nuts and fortified foods. Its absorption can be improved by consuming sources of vitamin C, including citrus fruits, tomatoes and peppers, alongside plant sources of iron.
Nevertheless, changing the diet alone is generally not enough to treat confirmed iron deficiency, particularly among women who continually lose blood through menstruation or whose requirements rise during pregnancy.
The Canadian Medical Association Journal review considers an iron-rich diet a supportive measure within a plan that includes replacing iron by the appropriate method and treating the underlying cause that led to depletion of the stores.
