Neutropenia (noo-troe-PEE-nee-uh) is an abnormally low count of neutrophils, a type of white blood cell that helps fight off infections, particularly those caused by bacteria and fungi.
The threshold for defining neutropenia varies slightly from one medical practice to another. Neutropenia in adults is generally defined as a count of 1,700 or fewer neutrophils per microliter of blood. The cell count indicating neutropenia in children varies with age.
The lower your neutrophil count, the more vulnerable you are to infectious diseases. If you have severe neutropenia — fewer than about 500 cells per microliter of blood — bacteria normally present in your mouth and digestive tract can cause infections.
Neutropenia may be caused by:
- Cancer or other diseases that damage bone marrow
- Congenital disorders characterized by poor bone marrow function
- Viral infections that disrupt bone marrow function
- Autoimmune disorders that destroy neutrophils or bone marrow cells
- Overwhelming infections that use up neutrophils faster than they can be produced
- Drugs that destroy neutrophils or damage bone marrow
Possible causes of neutropenia include:
- Alcoholism or chronic alcohol use
- Aplastic anemia
- Chronic idiopathic neutropenia in adults
- Drugs, such as antibiotics and diuretics
- Hepatitis A
- Hepatitis B
- Hepatitis C
- Hypersplenism, a premature destruction of blood cells by the spleen
- Hyperthyroidism (overactive thyroid)
- Kostmann's syndrome, a congenital disorder involving low neutrophil production
- Lyme disease
- Myelodysplastic syndromes
- Myelokathexis, a congenital disorder involving failure of neutrophils to enter the bloodstream
- Other autoimmune disorders
- Other congenital disorders
- Other infectious diseases
- Other parasitic diseases
- Radiation therapy
- Rheumatoid arthritis
- Salmonella infection
- Syndrome-associated neutropenia
- Vitamin deficiencies
Neutropenia is rarely an unexpected finding or simply discovered by chance. It's usually found on a white blood cell count that has been ordered to help diagnose a condition you're already experiencing. Talk to your doctor about what these results mean. The presence of neutropenia and results from other tests may already indicate the cause of your illness, or your doctor may suggest other tests to check your condition.
Because neutropenia makes you vulnerable to bacterial and fungal infections, take precautions to avoid these organisms. Wear a face mask, avoid anyone with a cold, and wash your hands regularly and thoroughly.