Presentation: Patient with microcytic anaemia with normal ferritin

A well 27-year-old woman is unexpectedly found to have an Hb level of 110 grams per litre (g/L) with a mean corpuscular volume (MCV) of 70 femtoliter (fl). She is keen to ensure that she is fit and healthy as she is planning a pregnancy. Her repeat full blood count is similar, and her ferritin is normal at 78 nanograms per millilitre (ng/ml).

• Individuals presenting with persistent microcytic anaemia with normal ferritin and iron studies may have an underlying haemoglobinopathy such as thalassaemia trait or sickle cell anaemia.
• These individuals are more commonly carriers, as affected individuals usually present earlier in life and more acutely.
• Most haemoglobinopathies are autosomal recessive and carriers are usually well, although they are at risk of having affected children depending on the carrier status of the other parent.
• If two carriers of an autosomal recessive condition have a child together, there is a one-in-four (25%) chance of that child being affected.
• Flags for an underlying genetic diagnosis include:
  • Mediterranean, Arabic, Asian or African ancestry (although haemoglobinopathies can occur in all ethnic groups);
  • family history of haemoglobinopathy; and
  • persistent microcytic anaemia with normal ferritin and iron studies.

• Send samples of the patient’s blood for haemoglobin electrophoresis.
• Confirmed carrier status for thalassaemia or a haemoglobin variant in individuals planning a pregnancy warrants a clinical genetics referral for partner testing and genetic counselling (in these patients, oral iron supplementation may not be necessary or beneficial).
• If a benign haemoglobin condition (such as Hb C disease, Hb D disease or Hb E disease) is identified, haematological advice and/or referral to the relevant specialty is advised.
• More rarely, sickle cell disease or beta thalassaemia may be diagnosed, requiring urgent haematological or paediatrics referral.
• For information about how to arrange testing in Wales, Scotland or Northern Ireland, see our dedicated Knowledge Hub resource.
• Information about patient eligibility and test indications were correct at the time of writing. When requesting a test, please refer to the National Genomic Test Directory to confirm the right test for your patient.

For clinicians

• National Institute of Diabetes and Digestive and Kidney Diseases: Sickle cell trait and other hemoglobinopathies and diabetes
• Online Mendelian Inheritance in Man (OMIM): # 603903, # 604131 and # 613985
• Public Health England: NHS Sickle cell and thalassaemia screening programme handbook (PDF, 89 pages)

References:

• Ryan K, Bain BJ, Worthington D and others. ‘Significant haemoglobinopathies: Guidelines for screening and diagnosis’. British Journal of Haematology 2010: volume 149, issue 1, pages 35–49. DOI: 10.1111/j.1365-2141.2009.08054.x

For patients

• NHS: Sickle cell disease
• NHS England: Thalassaemia
• Sickle Cell Society
• UK Thalassaemia Society