What Is Granulocytosis?

  • Hadiza BelloDoctor of Medicine - MD, All Saints University, Saint Vincent, UK
  • Nikita ShajiMaster of Science, Pharmaceutical Sciences, University of East London, UK

Granulocytosis is a state of having higher-than-normal numbers of granulocytes in your blood. Granulocytes are a group of blood cells referred to as white blood cells, whose primary function in the body is to fight infections and eliminate foreign materials from the body as a whole, but most especially the blood. These cells include neutrophils, basophils, and eosinophils. Neutrophils are the most prominent type of granulocyte.

Granulocytes are an important part of your body's immune system. They are essential parts of defence against bacterial and fungal infections. A decreased removal or increased production of neutrophils can lead to granulocytosis. Decreased removal may occur in cases of prolonged infections, while increased production may occur in cases of some cancers.


Granulocytosis is a vast term that encompasses a lot of different cells and conditions. Though it is a blanket term for an increase in the number of granulocytes in the blood, it is often not that straightforward. The cause, type, degree of increase, age, immune status and often genetics of the individual play a part in this condition

Causes of granulocytosis

  • Infection: Infections are one of the most common reasons for an increased number of granulocytes in the blood. This is because they are part of the innate immune system and are the body’s first line of defence against infections. In most cases, the type of granulocyte that is predominant during an active infection is usually the neutrophil.
  • Allergic reactions: Allergic reactions can trigger the body to release immune cells in the blood. In the case of allergies or parasitic infestations, the predominant granulocyte increase in the blood is the eosinophil.
  • Malignancies, also known as cancers, are conditions that are caused by the abnormal growth and division of cells in the body. Granulocytosis can be caused by malignancies of the blood and bone marrow, like leukaemias. However, the presence of any type of cancer in the body could trigger the release of granulocytes into the blood as the body recognises it as an intruder in some cases.
  • Autoimmune diseases are diseases that are caused by your immune system being overactive and attacking your body like it would a foreign invader. Granulocytes are the body’s first line of defence from foreign insults, leading to an increase in them in cases of autoimmunity.
  • Medications: drug-induced granulocytosis can be caused by drugs like corticosteroids and some platinum-based chemotherapy agents used to treat cancers like Non-small cell lung cancer (NSCLC). 
  • Smoking: Some studies1 have shown that people who smoke tobacco have higher levels of certain blood cell types, including granulocytes.
  • Physiologic causes: some cases of granulocytosis are normal and do not represent any abnormality. Conditions such as pregnancy, labour, and strenuous exercise could lead to an increase in the number of neutrophils in the blood. 

Signs and symptoms of granulocytosis

Because it often presents with nonspecific symptoms, it is often only detected during routine blood tests or while investigating other medical conditions. However, some individuals with granulocytosis may experience:

  • Fever
  • Nausea
  • Vomiting
  • Headache
  • Sweats
  • Itching
  • Enlarged lymph nodes

Management and treatment for granulocytosis

Treatment of the underlying cause is the best way to manage granulocytosis. Undetected, granulocytosis often resolves on its own as the body has autoregulatory systems that control the number of and type of cells in the blood. 

  • Antibiotics: granulocytosis that results from the body fighting an infection would often resolve after the infection has been resolved. Appropriate antibiotic therapy may be prescribed to aid the body in dealing with an infection.
  • Anti-inflammatory and anti-allergy medications: when caused by an allergic reaction, granulocytosis resolves if the agent causing the allergy is removed, or medications that combat the allergic symptoms are prescribed. If the condition is associated with an inflammatory disease, medications to control inflammation, such as corticosteroids or non-steroidal anti-inflammatory drugs (NSAIDs), may be recommended.
  • Cancer treatments: in cases of granulocytosis associated with cancers, chemotherapy, radiotherapy, or other targeted therapies may be used to manage the underlying condition.
  • Discontinuation of Medications: granulocytosis that is medication-induced is often quickly resolved after the discontinuation or dose adjustment of the offending medication. 


  1. Complete blood count (CBC): This is a test that measures the cell types in your blood and the quantities they existed at the time the blood was tested. It also allows healthcare providers to measure the amounts of each cell type in relation to the other cell types in the blood.
  2. Other blood screening: after your healthcare provider has determined the presence of granulocytosis in your blood, they will often order other blood tests to determine the cause of granulocytosis. This may be a more specific screening for infections, like a bacterial culture test or a cancer screening test.


How can I prevent granulocytosis?

It is difficult to point out a way to prevent granulocytosis since it is associated with a lot of underlying causes. However, maintaining a healthy lifestyle and proper management of chronic conditions may help in prevention. Regular routine medical checks with your healthcare provider could help in early detection and treatment. 

How common is granulocytosis?

Because granulocytosis can result from many different conditions, it is difficult to estimate how common it is. Neutrophilia, which is the most common type of granulocytosis, is seen most commonly in infants immediately after birth,2 smokers, and people who do strenuous exercise.

Who is at risk of granulocytosis?

  • People with infections 
  • Pregnant individuals
  • People with malignancies
  • Smokers
  • Certain genetic mutations.

How long does granulocytosis last?

The duration of granulocytosis depends on the cause, the amount of time it has been present in the individual, and the individual’s immune status. It may also depend on the effectiveness of treatment, if any is given. Because granulocytosis itself is a response to another condition, it often persists as long as whatever triggered it. Another important factor to note is that granulocytosis can be dynamic and fluctuates, for example, with strenuous exercise or pregnancy, where resolution is seen soon after the exercise is discontinued or where the individual is no longer pregnant.

When should I see a doctor?

Although granulocytosis can only be conclusively identified with the help of a blood test, it may present with symptoms like fatigue, fever, sweating and enlarged lymph nodes. If you have any of these symptoms or suspect you might have granulocytosis, it is important to consult a healthcare professional for proper evaluation and guidance.


Granulocytosis is characterised by an increased number of granulocytes, often neutrophils, in circulation in the bloodstream. It may signal a lot of other underlying processes going on in the body, such as inflammation, infection, or even cancer. Timely diagnosis and appropriate treatment of the underlying cause are important in the effective management of granulocytosis. By understanding the causes, symptoms, diagnosis, and treatment options of granulocytosis, individuals can take proactive steps toward maintaining their overall health and well-being.


  1. Elisia I, Lam V, Cho B, Hay M, Li MY, Yeung M, et al. The effect of smoking on chronic inflammation, immune function and blood cell composition. Sci Rep [Internet]. 2020 Nov 10 [cited 2023 Jun 25];10(1):19480. Available from: https://www.nature.com/articles/s41598-020-76556-7
  2. Assessment of neutrophilia - differential diagnosis of symptoms | bmj best practice [Internet]. [cited 2023 Jun 25]. Available from: https://bestpractice.bmj.com/topics/en-gb/1023
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Hadiza Bello

Doctor of Medicine - MD, All Saints University, Saint Vincent

Hadiza is a Medical Doctor who has worked in a clinical setting for five years, gaining valuable experience in diagnosing and treating a wide range of conditions.
She is currently pursuing an MSc in Infectious Diseases at the University of Kent
She is constantly exploring options to get involved in global health initiatives and is passionate about making healthcare more accessible and equitable for all.

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