Determine the most likely cause by arranging or assessing all of the following:
- Full Blood Count (FBC) (indicates severity and whether other cell lines are involved)
- Blood film (gives blood cell morphology which helps indicate the likely cause). This needs to be specifically requested on the laboratory form
- Reticulocyte count (indicates whether bone marrow is active). This needs to be specifically requested on the laboratory form. If reticulocyte count is:
- low i.e. decreased production - indicates nutritional anaemias, anaemia of chronic inflammation, renal failure, or bone marrow failure or infiltration
- normal, assess in relation to the mean cell volume (MCV)
- high i.e. increased destruction - indicates haemolysis or acute blood loss
- MCV identifies whether macrocytic (MCV more than 98), normocytic (MCV 82 to 98), or microcytic (less than 82)
Further investigations will depend on these results:
- Increased reticulocytes
- Look for haemolysis or acute blood loss
- Haemolysis:
- Determine whether it is congenital or acquired:
- Ask about family history e.g. hereditary spherocytosis, thalassaemias, sickle cell anaemia
- Macrocytic anaemia
- Consider alcohol excess, B12 deficiency or folate deficiency, hypothyroidism, primary bone marrow failure or bone marrow malignancy including multiple myeloma and secondary cancers
- Microytic anaemia
- Consider iron deficiency or anaemia of chronic inflammation. If neither of these, consider haemoglobinopathy such as thalassemia, and request haemoglobinopathy screen
- Anaemia of chronic inflammation
- Previously known as anaemia of chronic disease
- Can be caused by any systemic inflammatory condition e.g. malignancy, infection, autoimmune conditions
- May have normal or elevated ferritin and reduced serum iron
- May have an elevated C-reactive protein (CRP) and other inflammatory markers
- Can present as either microcytic or normocytic anaemia
- Normocytic anaemia
- Consider recent haemorrhage, renal failure, thyroid or other endocrine abnormality, anaemia of chronic inflammation or bone marrow malignancy including multiple myeloma and secondary cancers
- Cause is not obvious
- Measure:
- Ferritin, B12, folate
- Urea and electrolytes (U&Es) and liver function tests (LFTs)
- Thyroid-stimulating hormone (TSH)
- Serum protein electrophoresis plus urine Bence-Jones protein
Note: When iron deficiency coexists with inflammatory disease, ferritin may be spuriously normal - it is an acute phase protein. Requesting additional iron studies may assist in these situations.