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Iron deficiency anaemia

Iron deficiency anaemia is the most common cause of anaemia. Symptoms are related to the overall decrease in number of red blood cells and/or level of haemoglobin. The most common signs and symptoms include:

  • feeling of tiredness, fatigue
  • lack of energy

Symptoms that are more unique to iron deficiency and that may appear as iron stores in the body are increasingly depleted may include brittle or spoon-shaped nails, swollen or sore tongue, cracks or ulcers at the corners of the mouth, or a craving to eat unusual non-food substances such as ice or dirt (also known as ‘pica’).

Iron is an essential trace element and is necessary for the production of healthy red blood cells (RBCs). It is one component of haem, a part of haemoglobin, the protein in RBCs that binds to oxygen and enables RBCs to transport oxygen throughout the body. If not enough iron is taken in compared to what is needed by the body, then iron that is stored in the body begins to be used up. If iron stores are depleted, fewer red blood cells are made and they have decreased amounts of haemoglobin in them resulting in anaemia. Some of the causes of iron deficiency include:

  • Bleeding — if bleeding is excessive or occurs over a period of the time (chronic), the body may not replace sufficient iron or have enough stored iron to produce enough haemoglobin and/or red blood cells to replace what is lost. In women, iron deficiency may be due to heavy menstrual periods, but in older women and in men, the bleeding is usually from disease of the intestines such as ulcers, polyps and cancer.
  • Dietary deficiency — iron deficiency may be due simply to not eating enough iron in the diet. In children and pregnant women especially, the body needs more iron. Pregnant and nursing women frequently develop this deficiency since the baby requires large amounts of iron for growth. Lack of iron can lead to low birth weight babies and premature delivery. Pre-pregnant and pregnant women are commonly prescribed iron supplements to prevent these complications. Newborns who are nursing from deficient mothers tend to have iron deficiency anaemia as well.
  • Absorption problem — certain conditions affect the absorption of iron from food in the gastrointestinal (GI) tract and over time can result in anaemia. These include, for example, coeliac disease and Crohn’s disease.
Laboratory tests

Initial blood tests typically include a full blood count (FBC). Results may show:

  • Haemoglobin (Hb) — may be normal early in the disease but will decrease as anaemia worsens
  • Red blood cell indices — early on, the RBCs may be a normal size and colour (normocytic, normochromic) but as the anaemia progresses, the RBCs become smaller (microcytic) and paler (hypochromic) than normal.
    • Average size of RBCs (MCV) — may be decreased
    • Average amount of Hb in RBCs (MCH) — may be decreased
    • Increased variation in the size of RBCs (red cell distribution width (RDW))

A blood film examination may reveal RBCs that are smaller and paler than normal as well as RBCs that vary in size (anisocytosis) and shape (poikilocytosis).

If your doctor suspects that your anaemia is due to iron deficiency, s/he may run several follow-up tests to confirm the iron deficiency. These may include:

  • Serum iron — the level of iron in your blood; the result is usually decreased but is more reflective of recent iron intake rather than the body's true iron stores.
  • Ferritin — reflects the amount of stored iron in your body and is usually low. It is considered to be the most specific for identifying iron deficiency anaemia, unless infection or inflammation are present.
  • Transferrin and Total iron-binding capacity (TIBC)  — measurement of the protein that carries iron through the blood will be increased.

If the iron deficiency is thought to be due to abnormal blood loss, such as chronic bleeding from the gastrointestinal (GI) tract, then other tests and procedures may be performed. Laboratory tests that may be able to detect GI bleeding are:

A test for Helicobacter pylori may detect a bacterium that can cause ulcers in the GI tract that may be a cause of chronic bleeding. If any of these tests are positive or if it is strongly suspected that a GI bleed exists, then procedures such as endoscopy or colonoscopy may be done to find the location of the bleeding so that it can be treated.

Treatment of iron deficiency typically involves iron supplements. However, if iron-deficiency is suspected to result from abnormal blood loss, further testing is often required to determine the reason for the bleeding. When the underlying cause is found and treated, then the anaemia usually resolves.

Last Review Date: November 1, 2019