Bacterial Infection: This is the most common cause of an elevated white blood cell (WBC) count with a predominance of neutrophils. Neutrophilia is a hallmark of acute bacterial infections, as the body increases neutrophil production to fight off the invading pathogens.

Inflammatory Conditions: Conditions such as rheumatoid arthritis, gout, or other autoimmune diseases can cause an increase in WBC and neutrophil count due to the body's inflammatory response.
Trauma or Surgery: Physical trauma or recent surgery can lead to an elevated WBC count, including neutrophilia, as part of the body's response to injury.
Acute Stress: Severe psychological or physical stress can cause a transient increase in WBC and neutrophil count.

Sepsis: Although sepsis may present with a variety of white blood cell count abnormalities, an elevated neutrophil count can be an early sign. Sepsis is a life-threatening condition that requires immediate recognition and treatment.
Neutrophilic Leukemia: Although rare, certain types of leukemia, such as acute myeloid leukemia (AML), can present with an elevated neutrophil count. Missing this diagnosis could have severe consequences.
Severe Infections Requiring Specific Treatment: Certain infections like meningitis or endocarditis may present with elevated WBC and neutrophil counts. These conditions require prompt and specific antibiotic treatment to prevent serious complications or death.

Myeloproliferative Neoplasms: Conditions such as polycythemia vera, essential thrombocythemia, or primary myelofibrosis can sometimes present with an elevated neutrophil count, although this is less common.
Chronic Granulomatous Disease: A rare genetic disorder that affects the function of neutrophils, leading to recurrent infections and potentially an elevated neutrophil count.
Leukocyte Adhesion Deficiency: A rare immunodeficiency disorder characterized by recurrent infections and impaired neutrophil function, which might present with neutrophilia due to the body's attempt to compensate for the defect.