One relatively frequent abnormal lab we see (especially during the winter months) is a low absolute neutrophil count (ANC). Neutrophils are a type of white blood cells that fights bacterial infections. When their numbers get too low, it can increase the risk of serious bacterial infections. While some people have low ANCs that cause significant immune deficiencies and can lead to infection, the most commonly seen low ANC we see are brief dips after a viral infection. A low ANC is called neutropenia.
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Most causes of neutropenia are due to infection, drugs, severe malnutrition or immune disorders. The most common cause of neutropenia we see is after an infection. In most cases this type of neutropenia quickly resolves without any treatment. Some viruses, such as hepatitis B, Epstein-Barr, and HIV, are associated with prolonged neutropenias. The drugs that can cause neutropenia are not commonly used medications and routine testing for neutropenia would be done when those medications are used. Vitamin B12, folate, and copper deficiencies are very uncommon in children, but can lead to abnormal blood counts.
There are three levels of neutropenia:
- Mild: ANC 1000-1500
- Moderate: ANC 500-1000
- Severe: ANC less than 500
- If a child is overall healthy and growing well, the level is only mildly low (above 1000) I do not recheck the level -- though if your doctor wants to recheck it (or if you want it rechecked), that is appropriate to do.
- If the level is in the mid-range (500-1000) or if the child has had problems with recurrent infections or growth, I will usually recommend a confirmation (repeat test) and possible further evaluation.
- If the level is in the severe range (less than 500), it should be rechecked and the child should be closely monitored due to high risk of severe bacterial infections.
- Some physicians recommend repeating a blood count with any fever for a year in kids who have had any degree of neutropenia, so you'll have to talk to your child's doctor for a plan.
What symptoms might happen if the ANC is low?
When do we worry?
The level of ANC as well as the cause both determine the risk level of an overwhelming infection. An example would be when people are immune suppressed from chemotherapy, they are at very high risk of bacterial infections. On the other hand, an otherwise healthy person with a mildly low ANC is not more likely to get a bacterial infection than another person with a normal ANC.
We are concerned if the child has recurrent infections, poor growth, or a very low level. Each case must be evaluated by the person who ordered the test and who has recently seen your child.
What treatment is done for a low ANC?
Most children do not need any specific treatment. They are monitored for recurrent infections, especially infections that require antibiotics. They are also monitored for growth, since if a body is chronically sick, it often doesn't grow well.
Each infection that requires antibiotics is treated and blood counts might be checked to see how low they are at the time.
In children who have a chronically low ANC, I usually refer them to a hematologist (blood specialist) to evaluate why they have it and if it requires a special treatment that stimulates the bone marrow to make more neutrophils.