Anaemia is a condition in which the number of red blood cells (RBC) or the haemoglobin (Hb) concentration within them is lower than normal. It mainly affects women and children. Anaemia occurs when there isn’t enough Hb in the body to carry oxygen to the organs and tissues. In severe cases, anaemia can cause poor development in children. It can also cause problems for pregnant women and their babies. Anaemia is quite often preventable and treatable.
Anaemia is diagnosed based on Hb concentrations falling below specified levels based on age, sex, and physiological status. It is considered a symptom of an underlying condition(s). The causes of anaemia can be acquired or inherited. ‘Acquired’ means you aren’t born with the condition, but you develop it. ‘Inherited’ means your parents passed the gene(s) for the condition on to you. Sometimes the cause of anaemia is unknown.
Anaemia may be caused by several factors: nutrient deficiencies, inadequate diet (or the inadequate absorption of nutrients), infections, inflammation, chronic diseases, gynaecological and obstetric conditions, and inherited RBC disorders.
Iron deficiency is considered the most common nutritional deficiency leading to anaemia. Deficiencies in vitamin A, folate, vitamin B12 and riboflavin (vitamin B2) can also result in anaemia due to their specific roles in the synthesis of Hb and/or RBC production. Additional mechanisms include nutrient losses (e.g., blood loss from intestinal bleeding, haemorrhage associated with childbirth, or menstrual loss), impaired absorption, low iron stores at birth, and nutrient interactions affecting iron availability.
Infections can be another important cause of anaemia. Infections can impair nutrient absorption and metabolism or can cause nutrient loss. Many different chronic conditions can cause inflammation and lead to anaemia of inflammation or anaemia of chronic disease.
Consistent heavy menstrual losses, maternal blood volume expansion during pregnancy, and blood loss during and after childbirth, particularly in cases of postpartum haemorrhage, commonly lead to anaemia.
Additionally, in some parts of the world, inherited red blood cell disorders are a common cause of anaemia. These include conditions such as α- and β-thalassemia due to abnormalities of Hb synthesis, sickle cell disorders due to changes in the Hb structure, other haemoglobinopathies due to Hb gene variants, abnormalities of RBC enzymes, or abnormalities of the RBC membrane.
Signs and Symptoms
Common and non-specific symptoms of anaemia include:
- dizziness or feeling light-headed
- cold hands and feet
- shortness of breath, especially upon exertion
Severe anaemia can cause more serious symptoms including:
- pale mucous membranes (in the mouth, nose etc.)
- pale skin and under the fingernails
- rapid breathing and heart rate
- dizziness when standing up
- bruising more easily
Initial Laboratory Tests
Full Blood Count (FBC)
Anaemia may first be detected when a full blood count (FBC) is done as part of a health check or during investigations for another illness. FBC is a routine test that counts the number of each of the different types of cells in your blood. It gives your doctor information about the size, shape, and relative maturity of the blood cells present in your blood at that moment.
If results of the FBC indicate anaemia, it may be followed up with an examination of a blood film. Results from this may give clues to the cause of the anaemia. Several other tests can help discover the cause of the anaemia and then guide treatment. See the individual discussions of the different types of anaemia for more on these.