What is iron deficiency anaemia?

Iron deficiency is simply a lack of iron. Iron is an essential mineral required to produce haemoglobin in red blood cells, which transport oxygen from the lungs around to every cell in the human body. Healthy red blood cells are important for cognitive functions, muscle strength, the immune system and energy. The body can’t manufacture iron by itself, so iron must be sourced from food or another external source. If a person has low iron, they develop anaemia.

Iron deficiency anaemia impacts up to one sixth of the world’s population. It is a major public health problem which affects premenopausal women, pregnant women, and children, as well as those with chronic diseases. Iron deficiency anaemia commonly presents in patients with chronic diseases such as chronic heart failure, heart transplants, digestive disease, kidney disease and cancer. Common blood thinning medications such as aspirin, heparin and warfarin can interfere with the body’s ability to make haemoglobin. A poor diet, digestive disease or significant bleeding from ulcers, cancers or menstruation can also contribute to the condition. Other conditions such as pregnancy and kidney disease increase the demand for iron which can deplete an individual’s iron stores.

Common symptoms of iron deficiency anaemia include fatigue, headache, shortness of breath, restless legs, dizziness, chest pain and trouble concentrating. Common signs include a very pale complexion, diffuse hair loss, dry and rough skin, atrophic glossitis (a smooth tongue), difficulty thinking, rapid heart rate, and cardiac murmur. Routine observations performed by medical staff may pick up many of the signs and symptoms of the condition such as visual paleness, shortness of breath, increased work of breathing, headache, dry skin, increased pulse rate, dizziness, reduced alertness/confusion, poor memory and concentration, and cold hands and feet.

Blood tests will pick up low haemoglobin levels. The normal reference range for adult men is between 130 – 180 g/L and non-pregnant adult females 120 – 160 g/L. However, more insightful information is gained by measuring serum ferritin and transferrin saturation levels, serum soluble transferrin receptors, and the serum soluble transferrin receptors–ferritin index rather than just the classic red cell indices.

Iron deficiency anaemia can be absolute or functional. Absolute iron deficiency occurs when there are severely reduced stores of iron in the liver, spleen, and bone marrow. Absolute iron deficiency is defined by serum ferritin less than 200 ng/mL. In functional iron deficiency, patients have adequate iron stored but they are unable to support adequate iron mobilisation which is defined as ferritin greater than 200 ng/mL with TSAT (transferrin saturation) less than 20%. This commonly occurs in patients with systemic inflammation, as iron is withheld from the plasma and leads to production of iron deficient red blood cells.

Oral supplementation and increasing iron in the diet is usually the first line of treatment for patients with iron deficiency anaemia. However, this can take up to 3 months to take full effect and is not always well tolerated. In some cases, restoring iron may be required urgently, particularly if there is a background of malabsorption or there has been significant blood loss. In several disorders, including chronic kidney disease and postpartum, intravenous iron replenishes iron stores more effectively than oral supplementation. The modern versions of parenteral iron formulations provide safe, rapid, total-dose iron replacement.

A doctor will calculate an appropriate infusion dose based on the patient’s weight. Following this, a health care professional will apply a tourniquet to the arm, inserting a small needle, and replacing this with a small intravenous catheter. A prescribed intravenous iron infusion will be connected, which includes a bag suspended above the patient, attached via a line to the venous catheter. The infusion usually takes between 15-30 minutes. Blood transfusions can also occur as a treatment for iron deficiency anaemia, but they are used as a last resort. The patient will be closely monitored before, during and after the infusion takes place.

Some side effects have been reported in association with iron infusions. These include nausea, dizziness, constipation, swelling, diarrhoea, skin staining, fainting and hypotension. Rarely, in around 1 in 250,000 cases, a person may experience a severe allergic reaction causing a rash, severe itching and difficulty breathing. Other rare side effects include hypophosphatemia (low phosphate) and finally infection which can occur anytime a needle is introduced into the body. For this reason, intravenous iron infusions should only take place at facilities where staff are adequately trained to deal with anaphylaxis.

In summary, iron deficiency anaemia is a common condition which presents frequently, causing significant morbidity in the general population. It is particularly common in pregnant women and patients with chronic diseases such as cancer, kidney disease and heart failure. A lack of iron impacts the haemoglobin in red blood cells, reducing the capacity to transport oxygen. The good news is it can be readily treated. Your doctor is in the ideal position to identify the common signs and symptoms of iron deficiency anaemia, so if you have any concerns, make a visit to your GP or specialist to discuss your symptoms.