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Iron deficiency anaemia

 
Anaemia occurs when you have a low level of red blood cells in your blood. Iron deficiency anaemia is the most common type of anaemia, caused by insufficient iron to support the normal production of red blood cells.
 
Iron deficiency is the most common dietary deficiency in the world and mainly affects children and women (particularly pregnant women). In New Zealand, studies have indicated more than 7% of women and 1% of men have iron deficiency, a proportion of whom will show signs or symptoms of anaemia.

Causes

Red blood cells perform the important task of carrying oxygen (attached to a protein called haemoglobin or ‘haem’) around the body. Anaemia can occur as the result of reduced production, or an increased loss, of red blood cells. The body requires three essential elements – iron, vitamin B12, and folic acid – to produce red blood cells. Iron deficiency is the most common cause of anaemia.

Iron deficiency anaemia can be caused by not consuming enough food that contains iron, poor absorption of iron by the body, or loss of iron due to bleeding.
 
Babies are born with sufficient iron supplies to last for approximately six months of feeding with milk (breast or formula) alone.  After this time babies need iron rich or fortified foods gradually added to their diets to meet their bodies' iron requirements.
 
Children and teenagers go through spurts of rapid growth, which requires a great deal of iron.  A balanced diet with adequate amounts of iron is important at these times.
 
Iron deficiency anaemia occurs frequently among women of childbearing age.  In women who are not pregnant the cause may be due to heavy loss of blood during menstruation.  In pregnant women, iron stores have to serve the increased blood volume of the mother, as well as the needs of the growing baby. If sufficient iron intake is not maintained (either in the diet or in the form of iron supplements), iron deficiency anaemia can result.
 
In adults iron deficiency anaemia can occur as the result of blood loss from the digestive tract arising from long-term use of some medications (such as aspirin), gastric ulcers, duodenal ulcers or bowel cancer.  Conditions that affect the absorption of iron by the bowel (such as coeliac disease and Crohn's disease) and conditions that cause chronic inflammation (such as systemic lupus erythematosus and rheumatoid arthritis) may also lead to iron deficiency.

Signs and symptoms

The symptoms of iron deficiency anaemia become apparent once the body's stores of iron have been depleted.  Symptoms tend to appear gradually and may include: 

  • Fatigue
  • Weakness
  • Paleness of the skin, gums and nail beds
  • Reduced ability to fight infections
  • Difficulty concentrating
  • Headaches
  • Shortness of breath when exercising
  • Angina (heart related chest pain).
When iron deficiency is severe changes to the hair and skin, and abnormal growth of the fingernails, may occur.  There may also be dryness of the mouth and throat, and inflammation of the tongue (glossitis).  Long-term iron deficiency may cause developmental and learning problems in children.

Diagnosis

An assessment of symptoms and blood tests are used to diagnose iron deficiency anaemia.  Blood tests will look at the number of red blood cells and haemoglobin level, as well as the iron stores in the body.
 
When it is suspected that there is blood loss from the digestive tract, tests to detect blood in the bowel motions may be recommended. Diagnostic tests (eg: colonoscopy, gastroscopy) to investigate the digestive tract for the source of any blood loss may be performed.
 
It is important that the underlying cause of the deficiency is identified, as iron deficiency may be the first symptom of a more serious disorder.

Treatment

Treatment of iron deficiency anaemia will depend on the underlying cause of the deficiency.
 
Iron supplements may be prescribed and/or a change in diet recommended. In people who have poor absorption of iron through their digestive systems (eg: coeliac disease) regular iron injections may be prescribed.  Iron infusions through a vein in the arm may also be given. In cases where the anaemia is severe, a transfusion of red blood cells may be required.
 
If the underlying reason for iron deficiency is loss of blood from the digestive tract, treatment with medications or surgery may be required.

Prevention

The best way to prevent iron deficiency anaemia is to have sufficient iron in the diet. There are two main types of dietary iron: haem iron and non-haem iron.  Sources of haem iron include liver, red meat, chicken and fish. Haem iron is readily absorbed by the body.
 

Non-haem iron is found in whole grain cereals, vegetables (especially leafy green vegetables), fruits, nuts and legumes.  This type of iron is not so readily absorbed as haem iron. To assist the body to more readily absorb non-haem iron: 

  • Include a source of vitamin C with a meal
  • Consume meat with non-haem iron food
  • Avoid tea and coffee at meal times

The recommended daily dietary intake of iron is: 

  • Infants 7-11 months: 11mg
  • Children 1-8 years: 9-10mg
  • Children 9–13 years: 8mg
  • Teenage girls 14-18 years: 15mg
  • Teenage boys 14-18 years: 11mg
  • Women 19–50 years: 18mg
  • Pregnant women 14-50 years: 27mg
  • Breastfeeding women 14-50 years: 9-10mg
  • Women over 50 years: 8mg
  • Men over 19 years: 8mg
To put these quantities in perspective, a 250g beef steak may contain around 10mg of iron, a baked potato with skin around 2mg, and a chicken leg between 1 and 2mg.  Eating plenty of foods that contain iron is particularly important for children and pregnant or menstruating women. People who are strict vegetarians (particularly vegans) and people on weight reduction diets or rigorous exercise programmes also need to make sure they are getting a good source of iron in their dietary intake and/or in the form of iron supplements.

References

Grant, C.C., et al. Population prevalence and risk factors for iron deficiency in Auckland, New Zealand. J Paediatr Child Health. 2007;43(7-8):532-8.
Mayo Clinic Staff (2014). Iron deficiency anaemia. Mayo Clinic: Mayo Foundation for Medical Education and Research. http://www.mayoclinic.org/diseases-conditions/iron-deficiency-anemia/home/ovc-20266507 [Accessed: 20/12/16]
Ngan, V. (2016). Iron Deficiency. Hamilton: DermNet New Zealand Trust. http://www.dermnetnz.org/topics/iron-deficiency/ [Accessed: 19/12/16]
New Zealand Nutrition Foundation (2016). Iron. Auckland: NZ Nutrition Foundation. www.nutritionfoundation.org.nz/nutrition-facts/minerals/iron [Accessed: 19/12/16]
O’Toole, M.T. (Ed.) (2013). Iron deficiency anaemia. Mosby’s Dictionary of Medicine, Nursing & Health Professions (9th ed.). St Louis: Elsevier Mosby.
 
Last Reviewed -  December 2016 

  

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