18 Hidden Causes of High Neutrophil Counts That Doctors Want You to Know

Neutrophilia is a condition characterized by an excessive number of neutrophils in the bloodstream. As the body’s first line of defense against infections, neutrophils make up 40-60% of all white blood cells. In a healthy individual, neutrophil counts typically range between 2,500 and 7,500 per microliter of blood. When this balance is disrupted, neutrophilia can develop, signaling an underlying issue. To provide a clearer understanding, we have expanded our list to 18 key causes of neutrophilia, categorizing them into three primary groups. Reactive neutrophilia occurs in response to infections or stress, proliferative neutrophilia results from excessive production in the bone marrow, and demargination happens when neutrophils detach from blood vessel walls and remain in circulation. Treatment varies depending on the cause, ranging from antibiotics for infections to chemotherapy for leukemia or targeted therapies for autoimmune conditions. Identifying the root cause is crucial in determining the most effective treatment plan.

1. Arthritis

Individuals affected by arthritis may develop neutrophilia as a result. Neutrophils are the main type of white blood cell that contributes to the trigger and progression of arthritis. They play this role by releasing molecules that are toxic to other living cells in the body and molecules that mediate responses between macrophages and lymphocytes. Neutrophils in arthritis patients have different cellular properties than those in healthy individuals. Rheumatoid arthritis patients have neutrophils with delayed cellular death and a more sophisticated ability to generate reactive oxygen species, activate and deactivate certain genes, and expression of high-affinity FcY receptors on the cell membrane. These patients also have an immune system that exhibits a defect in their function of neutrophil clearance. In some autoimmune disorders, neutrophils may be the point of supply of the specific autoantigens or antibodies that propel the underlying mechanisms that result in the autoimmune disease. It is a combination of neutrophil apoptosis delay, clearance defects of neutrophils, and other abnormal properties of neutrophils that can cause an individual with arthritis to also be affected by neutrophilia.