1/ Neutrophils are the most abundant type of white blood cell in the human body, and provide a key component of our innate immune response. They are recruited to any site of acute inflammation and work by phagocytosing pathogens & releasing anti-microbial granules

2/ Key fact; neutrophils create/constitute pus...so it makes sense that neutrophilia is seen with almost every acute insult (e.g. infection, surgery, trauma) and can be significant (> 50 x 10^9/L). In this situation, the count will respond to treatment of the underlying cause

3/ More chronic insults can cause a more persistent neutrophilia (e.g. inflammatory disease, smoking) which is often mild and stable. Very rarely, neutrophilia can be related to an underlying bone marrow abnormality such as...

4/..CML or CMML. This will usually be a progressive neutrophilia with associated abnormalities such as basophilia/thrombocytosis, or monocytosis respectively. The blood film will often demonstrate dysplasia.

5/ There is no 'acute leukaemia' of neutrophils so even if a neutrophil count rises to 50 x10^9 or more for example over a few days post-op, this can only ever be inflammatory (aka a leukaemoid reaction). Chronic neutrophilic leukaemia (only neuts raised) is also incredibly rare

6/ Therefore consider discussion with haematology if there is a chronic, progressive neutrophilia with no underlying cause and if there are concerning features such as weight loss, splenomegaly or other blood abnormalities #blooducation #MedEd #juniordoctors #primarycare