Anaemia: migrant health guide

Advice and guidance on the health needs of migrant patients for healthcare practitioners.

Main messages

Around 2 billion people (over 30% of the world’s population) are anaemic.

Globally the most significant factor causing anaemia is iron deficiency, which is the most common and widespread nutritional disorder in the world.

Where you find a migrant patient to be anaemic, investigate as for any other patient. The determination of the cause is assisted by the blood film: microcytic, normocytic, or macrocytic.

The range of causes of anaemia that may be particularly pertinent to some migrant patients, including iron deficiency, haemoglobin disorders, and a wide range of infections to which some migrants may be at higher risk.

Treat anaemia based on its underlying cause.

The NHS antenatal screening programmes test for anaemia and haemoglobin disorders.


The World Health Organization defines anaemia in different age and/or gender groups as being less than the threshold values below for blood haemoglobin concentration:

Age or gender group Haemoglobin threshold (g/l)
Non-pregnant women (≥15 years) 120
Men (≥15 years) 130
Children (6 months to 4 years) 110
Children (5 years to 11 years) 115
Children (12 years to 14 years) 120
Pregnant women 110

See Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity, WHO Vitamin and Mineral Nutrition Information System, World Health Organization, 2011.

Classification and causes

You should investigate migrant patients for anaemia in the same way that you would investigate any other patient.

Anaemia is the result of a wide variety of causes that commonly co-exist, and is commonly classified according to the size of the red blood cells: microcytic, normocytic and macrocytic.

Certain causes of each type are relevant to consider in some migrant patients.


The main causes of microcytic anaemia to consider include:

  • iron deficiency anaemia - the most common cause of anaemia, probably accounting for around 50% of all anaemia globally, its main causes are:

    • dietary deficiency of iron
    • bleeding in the stomach and intestines which can be caused by a stomach ulcer, stomach cancer, bowel cancer, or by taking non-steroidal anti-inflammatory drugs (NSAIDs)
    • malabsorption of iron due to gastro-intestinal problems, or a diet high in phytates (for example legumes and whole grains) or phenolic compounds (eg tannins in tea and wine)
    • blood loss eg due to heavy menstruation or chronic parasitic infestation (for example hookworm, schistosomiasis, ascariasis), which can also lead to blood loss in people from the tropics
    • increased demands for iron eg during growth and pregnancy
  • Thalassaemias - a haemoglobin disorder
  • anaemia of chronic disease - can include chronic infections such as tuberculosis (TB) and HIV
  • lead poisoning - products used by some migrants which have a high concentration of lead include:

See non-infectious environmental hazard examples.


The main causes of normocytic anaemia to consider include:

  • anaemia of chronic disease - can include chronic infections such as tuberculosis (TB) and HIV
  • haemolytic anaemia - causes may include:

    • haemoglobin disorders (sickle cell disease, Thalassaemias)
    • inherited red cell enzyme deficiencies eg glucose-6-phosphate dehydrogenase (an x-linked disorder common in the Mediterranean, the Middle East, South East Asia and West Africa), and pyruvate kinase deficiency (common in Northern European populations)
    • haemolytic infections, including malaria
  • riboflavin deficiency


The main causes of macrocytic anaemia to consider include:

  • vitamin B12 deficiency, usually the result of:

    • pernicious anaemia in high income countries
    • dietary insufficiency in low income countries, particularly for those with a vegan diet
  • folate deficiency

Other micronutrient deficiencies can increase the risk of anaemia, such as:

  • vitamin A
  • copper

Macrocytic anaemia is also frequently linked to alcoholism, with or without liver disease.

Testing and treatment

Maintain vigilance for anaemia in at-risk people and investigate as normal, while bearing in mind that some migrants may be at increased risk of particular causes of anaemia.

Further laboratory investigations can help to differentiate the causes of anaemia and discuss with your local haematology laboratory as appropriate.

Treat anaemia on the basis of its underlying cause.

Antenatal screening

The UK National Screening Committee policy is to offer all pregnant women a test for anaemia.

In addition, NICE guidelines recommend offering antenatal screening for sickle cell diseases and thalassaemias to all women as early as possible in pregnancy, preferably by 10 weeks of gestation.

Preconception counselling (supportive listening, advice giving and information) and carrier testing should be available to all women who are identified as being at higher risk of haemoglobinopathies, using the family origin questionnaire from the NHS antenatal and newborn screening programme.

Resources has produced an anaemia leaflet.

The NHS Sickle Cell and Thalassaemia screening programme has published a number of publications in a range of languages.

NICE has produced clinical knowledge summaries on anaemia.

Published 31 July 2014