Iron Deficiency Anaemia

Approximately one in six people worldwide are affected by iron deficiency anaemia (IDA). It is the most common nutritional deficiency. Children below five, pregnant women and women of childbearing age are at the greatest risk of IDA.

The symptoms of IDA include weakness, fatigue, dyspnoea, headache, paleness and difficulty concentrating. Symptoms often vary between age groups, and IDA may also be asymptomatic. Iron is an essential nutrient that is indispensable for lots of different cellular mechanisms, including mitochondrial function, enzymatic synthesis and processes, and DNA synthesis and repair. It is also an essential part of the synthesis of myoglobin (found in muscles) and haemoglobin (found in red blood cells). Haemoglobin is essential for the transportation of oxygen by red blood cells.

An iron study blood test with low haemoglobin and low ferritin levels is an indicator of the presence of IDA. Serum iron levels may not accurately show the availability of iron in the body which is why an iron study panel blood test is required.

There can be many different causes of IDA. IDA may be due to increased intake requirements or demand due to menstrual blood loss, pregnancy, blood donation or other blood loss. It can be caused by insufficient iron intake due to patients eating a vegan/vegetarian diet or suffering from disordered eating. IDA may also be caused by malabsorption due to coeliac disease or inflammatory bowel disease. Other potential causes of IDA include medications, genetic causes or disease-related (such as anaemia of chronic disease).

Medications that may cause IDA include non-steroidal anti-inflammatory drugs (NSAIDs) and proton pump inhibitors (PPIs). NSAIDs can cause injury to the gastrointestinal tract resulting in ulcers and/or bleeding, which may precipitate IDA. PPI use can be associated with reduced absorption of other medications and nutrients. Gastric acid secretion affects the absorption of iron from the gastrointestinal tract. In a population-based case-control observational study, the use of PPIs for over one year by subjects was associated with a greater risk of iron deficiency.

IDA can have serious long-term outcomes. Children with IDA may have delayed cognitive development or difficulty concentrating. Adults with IDA may have reduced physical performance, including work productivity, and IDA is associated with a reduced quality of life, especially for women with heavy menstrual bleeding. Pregnant women with IDA are more likely to go into preterm labour, have neonates with lower weights, and IDA is also associated with an increased risk of neonatal and maternal mortality. Elderly people with IDA may experience cognitive decline.

Treatment of IDA should include investigation of the underlying causes and management where possible. For example, if IDA is due to blood loss during menstruation, consider options to reduce blood loss, such as contraceptive therapy. Treatment with iron therapy (oral or parenteral) is usually required to adequately and quickly replenish iron stores. Serum ferritin levels should be monitored to ensure adequate response to therapy. For long-term prevention of future IDA, patients may need to adjust their diets to include more iron-rich foods.

Oral iron therapy is inexpensive, simple to administer and is often more convenient for patients. Oral iron therapy’s side effects include black stools, constipation and nausea. Oral iron therapy is not suitable for patients with absorption issues.

The usual dose is 100mg to 210mg of elemental iron daily. It is best to take at least one hour before food, and it may interact with tea, calcium supplements, PPIs and antacids. Vitamin C assists iron absorption, and vitamin C/iron combination products are available. If gastrointestinal side effects occur, patients can try divided dosing or take iron supplements with food.

Children with IDA may be administered 3 to 6mg elemental iron per kg per day with a maximum dose of 210mg. There are less side effects with doses at the lower end of the range, and it may be beneficial to administer doses with juice containing vitamin C to increase absorption. Iron absorption is inhibited in children who consume a lot of milk and other dairy products (including bottle feeding). Where possible, it is recommended to reduce milk consumption to under 500mL per day in children aged between 1 and 5.

IV therapy is indicated for use in patients who cannot use oral therapy or where a quick response is required. IV is preferred over IM as absorption is poor from IM injection. IM injection may also be painful and discolour the skin. IV iron is more effective than oral iron at improving quality of life for patients with chronic medical conditions and pregnancy. IV iron is indicated for patients receiving dialysis and for IDA induced by chemotherapy. In a meta-analysis of over 10 000 subjects, iron infusions were not associated with severe side effects or an increased rate of infections. IV site reactions may occur, and there is a very small risk of anaphylaxis.

Ferric carboxymaltose (Ferinject^®) is suitable for rapid infusion and is generally well tolerated. This medication is indicated for patients 14 years and older. Iron polymaltose (Ferrosig^® / Ferrum H^®) has a long infusion time (typically around five hours) and is indicated for hospital inpatients. Iron sucrose (Venofer^®) is used for haemodialysis patients and other specialist settings. Please refer to dosing guides and local hospital protocols.

In summary, IDA is a common but potentially serious condition that requires iron therapy. Oral iron therapy is often used first line, but adverse effects may decrease patient compliance. IV iron therapy is indicated for severe IDA, patients with absorption issues, patients with chronic disease and for patients unable to tolerate oral therapy.