What is Neutropenia?

White Blood Cells
White Blood Cells. Science Photo Library - DR GOPAL MURTI/Brand X/Getty Images

Definition 

Neutropenia is a lower than normal neutrophil count.  Neutrophils are one of the white blood cells  involved in fighting infections.  Sometimes, but not always, patients with neutropenia also have leukopenia, a low white blood cell count.  

Neutropenia is generally defined as an absolute neutrophil count (ANC) of less than 1500 neutrophils per microliter of blood.  Neutropenia is divided into 3 categories by severity.

 

  • Mild:  ANC of 1000 – 1500 cells per microliter.
  • Moderate:  ANC of 500 – 999 cells per microliter. 
  • Severe:  ANC < 500.  

The risk of infection increased as the ANC decreases, particularly with severe neutropenia.

Symptoms of Neutropenia 

Neutropenia doesn't necessary cause any problems.  For some people, neutropenia will be caught on routine blood work.   Because neutropenia increases the risk of infection, neutropenia might be discovered during an illness.  Neutropenia increases the risk of infections in the skin and mucous membranes (lining of the mouth and GI tract).  This might include ulcers in the mouth, abscesses or boils, and rashes.   

Causes of Neutropenia 

There are numerous causes of neutropenia.  Some causes predominantly affect children while others are found in adults.   

  • Infection:  During infections, particularly viral infections, the ANC may decrease temporarily.  This is called viral suppression.  When the infection resolves, the neutrophil count returns to normal. 

  • Medications:  There are several medications, including antibiotics, medications used to treat malaria, and antiseizure medications, that can lower your white blood cell count and neutrophil counts.   Generally, when the medication is stopped, the neutrophil count returns to normal.  

  • Benign Ethnic Neutropenia:  This is generally a mild neutropenia with ANC > 1000 cells per microliter.  African-Americans have lower than normal ANC but this is not associated with increased risk of infection.   

  • Immune – mediated:  In children this process is often temporary and called autoimmune or benign chronic neutropenia.  In adults this may be secondary to a larger autoimmune disease like lupus or rheumatoid arthritis

  • Aplastic anemia:  Aplastic anemia is a disease that cause poor bone marrow functioning.  Although anemia is in the name, usually all three blood cells (white blood cells, red blood cells, and platelets) are low.  

  • Leukemia:  Leukemia is a cancer of the white blood cells.  These generally involve the lymphocytes, a different type of white blood cells.  As the number of these cancerous lymphocytes grow, the ANC can be reduced.   

  • Chemotherapy:  Chemotherapy destroys the rapidly dividing cells in your body, which includes your white blood cells, red blood cells, and platelets.  

  • Inherited disorders that affect bone marrow function:  This includes a large group of disorders such as, severe congenital neutropenia (also known as Kostmann syndrome), Fanconi anemia, Shwachman Diamond Syndrome, and Cyclic Neutropenia. 

  • Vitamin deficiencies:  Rarely deficiencies in vitamin B12, folate, or copper may result in neutropenia.  

How is Neutropenia diagnosed? 

Neutropenia is diagnosed with blood work, called a complete blood count. (CBC)  This may be automatically calculated on the CBC and is called the ANC, absolute neutrophil count.  Your healthcare provider can also calculate your ANC by multiplying your total white blood cell count by the % neutrophils reported in the differential. After 1 year of age the normal ANC is 1500 cells per microliter.

If the neutropenia is thought to be secondary to an illness or a medication, your physician may simply get several CBCs over time to see if the ANC is improving.  Determining the cause of neutropenia can be challenging and you may be referred to a hematologist, a physician who specializes in blood disorders, for further work-up.  This will likely include additional blood tests and potentially a bone marrow aspirate and biopsy.  This procedure requires a needle to be placed in a bone (usually in the pelvis) to remove the sample of both the liquid and solid portion of the bone marrow.   

Treatments of Neutropenia 

  • Observation:  If the neutropenia is mild, your healthcare provider may opt to monitor your ANC on a regular basis.  Also, children with autoimmune neutropenia are at low risk of infection and usually do not need treatment. 
  • Stopping medication:  If a particular medication is causing your neutropenia, your physician may ask you to stop taking this.  This can be a challenging decisions as the risk of neutropenia must be carefully weighed against the risk of stopping the medication. 

  • Chemotherapy:  If your neutropenia is caused by leukemia or another cancer, you may be treated with chemotherapy. 

  • Antibiotics:  You may be given antibiotics to try to prevent infections, caused prophylaxis.       

  • Immune suppressing medication:  This treatment is used when neutropenia is triggered by an autoimmune disease or to treat aplastic anemia.  

  • Bone marrow transplant:  If the neutropenia is a result of an inherited bone marrow failure this may be the treatment of choice.  Also, this is not an uncommon treatment for aplastic anemia.   

  • White blood cell growth factors:  This may be called G-CSF or filgrastim.  These are medications used to stimulate the bone marrow to produce more white blood cells, particularly neutrophils.  This medication can be given to patients receiving chemotherapy to attempt to reduce the length of time the patient has severe neutropenia.  

The bigger problem is that as your neutrophil count lowers, your risk of having a serious bacteria infection increases.  This is particularly true for patients with severe neutropenia.  If you have neutropenia, your physician should discuss what should do if you develop a fever.  This often involves being admitted to the hospital to have lab work drawn and to receive antibiotics.  Antibiotics are given empirically, that is in anticipation that there is an infection; if no infection is identified, the antibiotics can be stopped.  

References

Christopher Gibson and Nancy Berliner.  How we evaluate and treat neutropenia in adults.  Blood. 2014;124(8):1251-1258.

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