White blood cells are a key part of the immune system. They help the body fight off germs like bacteria and viruses.

There are different kinds of white blood cells, and each plays a special role:

• Neutrophils increase during bacterial infections or inflammation
• Lymphocytes may rise with viral infections or certain immune conditions
• Monocytes help clean up damaged tissue and can increase with chronic infections
• Eosinophils and basophils may rise with allergies or parasitic infections

When your child has too many white blood cells, it’s called leukocytosis. Leukocytosis may be a sign of an infection, inflammation or another everyday medical issue. In other cases, it may be due to an immune disorder or blood disease.

Your child’s care team will do tests to find out what’s causing the problem and create a plan to treat it.

Not all high white blood cell counts mean something serious. In children, it’s often a sign that the body is doing its job. It may be in response to:

• Mild infections like colds, strep throat or ear infections
• Recent vaccinations
• Teething or other sources of stress
• Minor injuries, like cuts or bruises
• Strenuous activity or high fevers

These changes are usually temporary.

In some cases, a high white blood cell count may point to a more complex medical condition. These are usually rare. Your child’s care team will look at the full picture and let you know if they want to do more tests.

Signs that something more complex is happening include:

• The white blood cell count stays high over time
• Unexplained fevers
• Swollen lymph nodes
• Poor growth

Below are some of the more complex causes of high white blood cells that we treat.

Neurocutaneous Syndromes

These genetic conditions affect both the skin and nervous system. Neurocutaneous syndromes can have immune system changes:

• Tuberous sclerosis: Tumors grow in parts of the body, including the brain and skin.
• Neurofibromatosis: Nerve tumors grow and may cause skin changes. Kids with this disease also often have learning challenges.
• Sturge-Weber disease: Birthmarks on the face, brain abnormalities and sometimes seizures or learning delays.

Histiocytosis Disorders

These rare diseases occur when the body makes too many white blood cells called histiocytes. Histiocytosis disorders can cause inflammation or organ damage:

• Hemophagocytic lymphohistiocytosis: A life-threatening immune reaction where histiocytes attack the body’s tissues.
• Langerhans cell histiocytosis: Histiocytes build up in parts of the body like bones, skin or organs, causing damage.

Lymphoproliferative Disorders

Autoimmune lymphoproliferative syndrome is a disorder where the body makes too many lymphocytes. It can cause swollen lymph nodes, enlarged organs and a higher risk of infections.

Eosinophilic Disorders

Eosinophilic disorders are a rare set of conditions where high levels of eosinophils build up in tissues in the body. It causes belly pain, vomiting or trouble gaining weight.

Autoinflammatory and Periodic Fever Syndromes

Symptoms of autoinflammatory and periodic fever syndromes include repeated fevers and inflammation. These happen even when there’s no infection:

• Familial Mediterranean fever: Regular episodes of fever and pain in the belly, chest or joints.
• Hyper-IgD syndrome: Frequent fevers, rashes and swollen lymph nodes.
• TNF receptor-associated periodic syndrome: Repeated episodes of fever, muscle pain and rash.
• PFAPA syndrome: Repeated episodes of fever, mouth sores, sore throat and swollen neck glands. A common childhood condition.

Specific treatment for disorders related to high white blood cell counts depends on:

• Your child’s diagnosis
• Their age
• Their overall health
• How their body responds to treatment

Some children need short-term care. Others may need ongoing support from our experts.

At Children’s Wisconsin, the Kids with Immune Dysregulation Disorders (KIDDs) Program cares for kids with immune disorders. This clinic brings together experts of all kinds to build a care plan that fits your child’s unique needs.

Treatment options may include:

• Steroids or other medicines to calm down an overactive immune system
• Targeted therapies that block specific proteins or immune signals
• Biologic medicines such as monoclonal antibodies
• Chemotherapy or immune-modulating drugs for more severe or life-threatening disorders
• Bone marrow transplant for certain genetic or immune system conditions
• Nutritional support and symptom management to help your child grow and feel their best
• Infection prevention plans and tailored vaccines, if needed

Your care team will help you understand every step of the process and adjust treatment as your child grows.