Red blood cells (RBC) contain haemoglobin, a protein that enables oxygen to be carried from the lungs to the body. When the number of RBCs is reduced, or they are not healthy, the blood cannot carry a sufficient amount of oxygen. An inadequate supply of oxygen in the tissues causes the symptoms associated with anaemia.

Prevalence

Anaemia is a serious global health concern, predominantly affecting children and pregnant women. The World Health Organization (WHO) estimates that 42% of children under age 5 and 40% of pregnant women around the world suffer from anaemia.

Data collected between 1993-2005 from the WHO Vitamin and Mineral Nutrition Information System found that an estimated global prevalence of anaemia was 24.8% (1.62 billion people). Results from the Global Burden of Disease Study 2019 reported that 1.8 billion people worldwide were anaemic.

Causes

• Congenital (present at birth)
• Hereditary
• Acquired
• The body does not make enough RBCs
• Bleeding – lose RBCs more quickly than they can be replaced
• The body destroys RBCs

Symptoms

Signs and symptoms can vary depending on the cause and severity of the anaemia, and may include the following:

• Fatigue, tired
• Unexplained weakness
• Pale or yellowish skin
• Irregular heartbeats
• Shortness of breath
• Dizziness or light-headedness
• Chest pain
• Cold hands and feet
• Headaches

Risk factors

The following can increase the risk of anaemia:

• A diet low in iron, vitamin B-12, folate and copper.
• Having an intestinal disorder (e.g., Crohn’s or celiac disease) affects nutrient absorption.
• Menstruating women have a higher risk of iron deficiency and a loss of RBCs.
• Pregnant women and women not taking folic acid and iron supplementation.
• Chronic conditions such as cancer can lead to a shortage of RBCs.
• Slow blood loss within the body (e.g., from an ulcer) can deplete the body of iron.
• Family history.
• Infections, blood diseases and autoimmune disorders.
• People aged over 65 years.

Types of anaemia

Anaemia can be temporary or long term; mild or severe.

Iron deficiency anaemia – this common type of anaemia is when the body lacks appropriate levels or iron. Iron is needed to produce sufficient levels of haemoglobin to carry oxygen around the body. Symptoms include tiredness and shortness of breath.

Vitamin deficiency anaemia – the body lacks healthy RBCs caused by a reduction in vitamin B-12 and folate. Without sufficient levels of these nutrients, the body produces RBCs which are too large and do not work properly; therefore, reducing their ability to carry oxygen. Symptoms include fatigue, SOB and dizziness.

Aplastic anaemia – when the body stops producing enough new blood cells and can lead to uncontrolled bleeding and an increased risk of infections. This condition is rare and serious and can develop at any age; develop suddenly or over time. In addition to the above symptoms, additional signs or symptoms may present – aplastic anaemia can have unexplained or easy bruising; nosebleeds, bleeding gums, and prolonged bleeding from cuts; skin rash; and fever.

Thalassemia – this is an inherited blood disorder which causes the body to have less haemoglobin than normal. Mild thalassemia may not require treatment however, severe forms might involve ongoing blood transfusions. In addition to the above symptoms, additional signs or symptoms may present – facial bone deformities; slow growth; abnormal swelling; and dark urine. 

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References

• Overview of Anemia - Blood Disorders - Merck Manuals Consumer Version
• Anemia - Symptoms and causes - Mayo Clinic
• Anaemia (who.int)
• Worldwide prevalence of anaemia, WHO Vitamin and Mineral Nutrition Information System, 1993-2005 - PubMed (nih.gov)
• Burden of anemia and its underlying causes in 204 countries and territories, 1990–2019: results from the Global Burden of Disease Study 2019 | Journal of Hematology & Oncology | Full Text (biomedcentral.com)