Iron-Deficiency Anaemia: Understanding the Signs, Causes and Treatment

Iron deficiency is one of the most common nutritional deficiencies worldwide and is particularly common among women of reproductive age. The good news is that it is usually treatable. The important part is identifying whether you are iron deficient, whether you have developed anaemia, and what is causing the deficiency.

Iron is needed to produce haemoglobin, the protein in red blood cells that carries oxygen from the lungs to the body’s tissues.

When iron stores become depleted, the body may initially compensate and maintain a normal haemoglobin level. This is iron deficiency without anaemia.

If the deficiency becomes more severe, haemoglobin can fall and iron-deficiency anaemia develops. With less haemoglobin available to carry oxygen, the body may struggle to meet its oxygen demands, producing symptoms such as fatigue and breathlessness.

This distinction matters because you can have depleted iron stores even when your haemoglobin is still within the normal range.

Symptoms vary depending on how severe and how quickly the deficiency develops. Common symptoms include:

Some people have few or no noticeable symptoms, particularly in the earlier stages.

Iron deficiency can affect anyone, but women of reproductive age are particularly vulnerable because of menstrual blood loss.

In some cases, however, there is no obvious explanation at first.

And that is where proper investigation becomes important.

A full blood count (FBC/CBC) measures haemoglobin and provides information about your red blood cells.

To assess iron stores, doctors commonly use ferritin.

Ferritin reflects the amount of iron stored in the body, and a low ferritin generally indicates depleted iron stores. Depending on the clinical situation, additional tests such as transferrin saturation may also be requested.

This is why assessing suspected iron deficiency should not always stop at a haemoglobin measurement.

Diet plays an important role in maintaining adequate iron intake.

Sources include:

Iron from animal foods is predominantly haem iron, which is generally absorbed more efficiently. Plant foods provide non-haem iron, whose absorption is more affected by other foods and compounds in the meal.

You can support non-haem iron absorption by pairing iron-rich foods with vitamin-C-rich foods, including peppers, citrus fruits, berries and tomatoes.

Tea and coffee can reduce non-haem iron absorption when consumed with meals, so leaving some time between them and iron-rich meals may be beneficial.

If dietary intake alone is not enough to correct the deficiency, oral iron may be recommended.

Iron tablets can be effective, but gastrointestinal side effects are common. Constipation, nausea, abdominal discomfort and darker stools can occur.

Treatment also requires patience. Haemoglobin may start responding within several weeks, while replenishing depleted iron stores can take longer. Follow-up blood tests help determine whether treatment is working and how long it should continue.

The appropriate dose depends on the individual and should be determined with a healthcare professional.

Oral iron is not suitable or effective for everyone.

Intravenous (IV) iron may be considered when oral iron cannot be tolerated or absorbed adequately, when there is ongoing blood loss, or when a clinician determines that more rapid iron replacement is appropriate.

Examples include Monofer (ferric derisomaltose) and Venofer (iron sucrose).

IV iron can replenish iron stores more quickly than oral treatment, although the time it takes to feel better varies between individuals.

The amount administered and whether further infusions are required depend on the preparation used and the individual’s iron requirements. There is no standard schedule that means everyone needs an infusion every six months.

Flushing, dizziness, nausea or breathing symptoms can occasionally occur during an infusion and should be reported immediately to the healthcare professional administering the treatment. Serious hypersensitivity reactions are uncommon, but they can occur, which is why monitoring during treatment is standard practice.

Finding the reason for the deficiency

Insufficient intake — not consuming enough iron to meet the body’s requirements.

Poor absorption — conditions affecting the gastrointestinal tract can interfere with iron absorption.

Blood loss — heavy menstrual bleeding is common, but blood loss can also occur elsewhere in the body.

Increased requirements — pregnancy and certain physiological circumstances increase the body’s need for iron.

Persistent or unexplained iron-deficiency anaemia can sometimes indicate gastrointestinal blood loss. Causes range from relatively common gastrointestinal conditions to, less commonly, colorectal (colon) cancer.

Having iron-deficiency anaemia does not mean you have cancer. However, unexplained anaemia warrants appropriate investigation, particularly in men and postmenopausal women, where menstrual blood loss is not an explanation.

Iron deficiency is common and treatable, but good treatment is more than replacing a nutrient.

It means understanding your blood results, restoring iron when necessary, supporting adequate dietary intake and identifying what caused the deficiency.