Neutropaenia
March 30th, 2020
Overview
Neutropaenia refers to a reduction in circulating neutrophils.
Neutropaenia confers increased risk of infections - particularly bacterial and fungal - and fevers in these patients (febrile neutropaenia) are medical emergencies that require prompt investigation and treatment.
Severity of Neutropaenia
- Mild: 1.0 - 1.5 x 10⁹/L
- Moderate: 0.5 - 0.9 x 10⁹/L
- Severe:
Aetiology
- Acute neutropaenia is commonly caused by viral infections and certain other infectious states. Dietary deficiency, and in particular B12 and folate deficiency, can cause neutropaenia.
Bone marrow pathologies tend to cause pancytopaenia more commonly than isolated neutropaenia, as does cytotoxic chemotherapy. Other medications may cause dose-related or idiosyncratic neutropaenia.
Any condition that induces hypersplenism (including cirrhosis, certain infections, myeloproliferative disorders and chronic haemolytic anaemia), can cause sequestrational loss of neutrophils. Felty's syndrome is the triad of rheumatoid arthritis, splenomegaly and neutropaenia, and is associated with poorer prognosis in the RA patient. Other autoimmune conditions such as SLE may also cause neutropaenia and should be considered.
There are many congenital syndromes that cause chronic neutropaenia; these range from benign to severe and progressive.
Causes of Neutropaenia
- Congenital - benign familial neutropaenia, cyclic neutropaenia, severe congenital neutropaenia, certain congenital syndromes
- Bone marrow pathology - aplastic anaemia, myelofibrosis, myelodysplasia, acute leukaemia, lymphoma, cancer metastasis
- Infection - viruses, mycobacteria, typhoid, brucellosis, rickettsia, severe sepsis
- Autoimmune - primary autoimmune neutropaenia, SLE, rheumatoid arthritis (Felty's syndrome)
- Drugs - cytotoxic chemotherapy, NSAIDs, sulfasalazine, clozapine, many others
- Dietary deficiency - B12, folate, copper, alcohol abuse, severe malnutrition
- Chronic idiopathic neutropaenia
- Hypersplenism
Pearls
- Ask about family history of low white blood cells
- Ask about high risk features such as fevers, poor appetite, weight loss and night sweats
- Examine for lymphadenopathy and splenomegaly
- Correlate the onset of the patient's neutropaenia with the commencing and cessation of certain medications
- Do not delay investigation and treatment of febrile neutropaenia!
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