Neutropenia (noo-troe-PEE-nee-uh) is an abnormally low level of neutrophils. Neutrophils are a common type of white blood cell important to fighting off infections — particularly those caused by bacteria.

For adults, counts of less than 1,500 neutrophils per microliter of blood are considered to be neutropenia. For children, the cell count indicating neutropenia varies with age.

Some people have lower-than-average neutrophil counts, but not an increased risk of infection. In these situations their neutropenia isn't a concern. Neutrophil counts less than 1,000 neutrophils per microliter — and especially counts of less than 500 neutrophils per microliter — are always considered to be neutropenia, where even the normal bacteria from your mouth and digestive tract can cause serious infections.

Cancer chemotherapy is probably the most common cause of neutropenia. People with chemotherapy-related neutropenia are prone to infections while they wait for their cell counts to recover.

Neutrophils are manufactured in bone marrow — the spongy tissue inside some of your larger bones. Anything that disrupts neutrophil production can result in neutropenia.

Neutropenia is usually found when your doctor orders tests for a condition you're already experiencing. It's rare for neutropenia to be discovered unexpectedly or by chance.

Talk to your doctor about what your test results mean. Neutropenia and results from other tests might indicate the cause of your illness. Or, your doctor may suggest other tests to further check your condition.

Because neutropenia makes you vulnerable to bacterial and fungal infections, your doctor will probably advise certain precautions. These often include wearing a face mask, avoiding anyone with a cold, and washing your hands regularly and thoroughly.

Jan. 20, 2016