Hello Kerrilynn01,
By far, the most common reason for this is continued viral infections. Children this age average about 12 viral infections per year, almost all of them grouped in the winter. Because of this, these children tend to go from one cold to the next.
There are other causes of this. In particular, it is important to be sure that it is actually the lymphocytes that are high and not the neutrophils that are low. The percentages given are percentages of the overall white blood cell count. A drop in one cell line will result in an increase in the others.
If there is a thought that your son may still have a viral infection and there are no other concerning symptoms it may be worthwhile repeating the
CBC in a few weeks. If there is concern about something else that may be going on I would recommend your son be evaluated by a hematologist (a blood specialist).
Best wishes.
Advice and opinions given are based on the information provided and must not be used as an official medical recommendation. The limitations of the internet prevent an appropriate evaluation. Always consult your doctor if there is concern.
