Neutropenia: what a low neutrophil count means, causes, symptoms and treatment

Neutrophils are a type of white blood cell. Blood Cancer UK explains that if you have a low number of them, it is particularly hard for your immune system to deal with infection, which is called neutropenia, or being neutropenic.

It is found with a full blood count. Blood Cancer UK says the neutrophil count is written as a number times 10^9 per litre of blood, for example 1.5 x 10^9/L, and the first figure is the important one. It says 1.5 or more is normal for many people of African or Middle Eastern heritage and 1.8 or more is normal for other ethnic groups.

NHS Highland guidance gives a normal count as 2 to 7 x 10^9/L and defines neutropenia as below 1.5 x 10^9/L. The two UK sources use slightly different cut-offs, so ask your team which range they use for you.

Blood Cancer UK says neutropenia can be caused by the blood cancer itself, or by treatment, particularly chemotherapy, stem cell transplant or immunotherapy. NHS Highland guidance lists a wider range of causes that doctors look for when a low count is found.

• Medicines (your doctor or pharmacist can check the BNF).

• Viral infections.

• Autoimmune disease.

• Vitamin B12 or folate deficiency.

• Sepsis.

• Hypersplenism, Felty's syndrome, thyroid dysfunction or nutritional deficiencies such as anorexia nervosa.

• Bone marrow failure disorders such as myelodysplasia and aplastic anaemia.

• Bone marrow infiltration, for example acute leukaemia.

• Congenital syndromes such as cyclical neutropenia.

• Ethnic variation: NHS Highland says this is common in people of Black African or Middle-Eastern ethnicity and these people are not at increased risk of infection.

Neutropenia itself does not usually have symptoms of its own in the sources we read. The risk is infection. NHS Highland guidance says doctors ask about recurrent infections and mouth ulcers when taking a history, and examine for signs of autoimmune disease, liver disease and enlarged glands or spleen.

Blood Cancer UK says to get medical advice as soon as you notice any symptoms of infection, especially if you are neutropenic. It lists the following signs of sepsis: slurred speech or confusion, extreme shivering or muscle pain, passing no urine in a day, severe breathlessness, feeling like you are going to die, and mottled or discoloured skin. On black and brown skin, discolouration may be easier to see on the palms of the hands or soles of the feet. It also notes that symptoms can be mild.

Blood Cancer UK says people with neutropenia are at particularly high risk of sepsis, and that neutropenic sepsis is more common in people who are immunosuppressed because of blood cancer. It says: get help immediately if you are neutropenic and think you have an infection, call the 24-hour emergency number you have been given, or dial 999 and follow the advice.

NHS Highland guidance says that if a patient with a neutrophil count below 1 x 10^9/L presents with fever or clinical signs of sepsis they should be admitted and treated with intravenous antibiotics under the neutropenic sepsis policy.

Treatment depends on the cause. NHS Highland guidance says management varies depending on the likely cause, previous blood counts and clinical concern. Causative medicines may not need to be stopped if they are important and the neutrophil count is above 1 x 10^9/L with no recurrent infections.

Blood Cancer UK says some people may benefit from a growth factor medicine known as G-CSF, which encourages the bone marrow to make more blood cells including white blood cells, and that you should ask your hospital team if they think it would help. It also says you may be told to be extra careful about infections and to adjust your diet while at risk, and to follow your doctor or nurse's advice.

NHS Highland guidance says neutropenia associated with viral infection may persist for weeks and less commonly for some months. For a count that is only mildly low, it says doctors usually repeat the test, for example in four weeks for a count of 1.5 or above, or in two to four weeks for 1 to 1.49, and seek specialist advice if it stays low.

It says someone whose neutrophil count stays persistently below 1 x 10^9/L after a repeat at two weeks needs haematological assessment, and that a formal referral is made if there are other blood count abnormalities, abnormal examination findings or recurrent infections.

NHS Highland guidance suggests a set of investigations for a low neutrophil count, chosen according to the history and examination.

• Liver function tests.

• HIV, hepatitis B and hepatitis C tests.

• A blood film.

• Thyroid stimulating hormone (TSH).

• Vitamin B12 and folate.

• Ferritin.

• An autoimmune screen if the history or examination suggests it.

On the NHS, a low neutrophil count is often found on a routine full blood count in primary care, where a GP can repeat it and arrange tests. Persistent or severe neutropenia, or neutropenia with infection or other abnormal results, is referred to haematology. People having cancer treatment are looked after by their oncology or haematology team with a 24-hour contact number.

Private blood tests and haematology consultations are available, but fever in a neutropenic person should always go straight to emergency care.