An old article; unearthed an old BMJ I’d saved but never got round to making notes on. BMJ 2014;349:g5340.
Neutropenia is defined as a neutrophil count <1.5 x 10^9. It’s classified in increments of 0.5 (1 – 1.5 is mild, 0.5 – 0.9 is moderate, and <0.5 is severe). It may be normal in some ethnic groups; benign ethnic neutropenia affects 25 – 50% of people of African/Afro-Caribbean origin, plus some of Arabic/Middle Eastern origin, and has no clinical significance. This article therefore recommends using a cutoff of 1.0 rather than 1.5 for investigating people of Afro-Caribbean ancestry.
- Drug-related (cytotoxic drugs or idiosyncratic effect)
- Acute infection – usually viral (infectious mononucleosis, CMV, toxoplasmosis) – usually resolves in 3 – 4 weeks
- Chronic viral infection – HIV, Hep B, Hep C
- Auto-immune diseases – e.g. SLE, Sjogren’s, RA (may be due to the drug treatment or the underlying disease – normally only shows up in cases that are otherwise symptomatic)
- Haematological malignancy*
- Marrow infiltration (eg mets)*
- Haematinic deficiency*
- Copper deficiency or deficiency of other trace elements*
- Starvation (eg anorexia) – partly due to haematinic deficiencies, partly due to serous atrophy of the marrow
- Primary immune neutropenia – normally shows up in early childhood and remits spontaneously, rare in adults
- Chronic idiopathic neutropenia – diagnosis of exclusion, may be immune-related
(*Normally affects other cell lines as well)
- Blood film if moderate or severe
- Haematinics – rare for deficiency to cause isolated neutropenia, but authors recommend as is straightforwardly treatable cause (I’m more wary – we’ve had a lot of problems with borderline B12s getting picked up and overtreated and the lab is now warning us against overtesting).
- Monospot and/or acute virology – may be useful if clinical features (fever, sore throat, general malaise) or if blood film shows reactive T-cells
- Viral serology for HIV/Hep B & C for persistent unexplained neutropenia
It is not normally worth bothering with checking for autoimmune diseases in the absence of other symptoms, as unlikely to show up as first symptom and a positive ANA/RF in an otherwise asymptomatic patient is only going to lead to confusion/overtreatment.
- Other features suggest serious underlying disease
- Neutrophils persistently < 1.0
- Persistent downward trend
Depending on severity and on need for the drug in question, may have to weigh up the risks of continuing vs. stopping.