What Are the Causes of Elevated White Blood Cell Count?
Aug 18, 2021
Source: Cainiu Health
Dr. Xing Jian
Introduction
An elevated white blood cell (WBC) count in clinical practice—such as in cases associated with fever—may indicate an infection. However, an increased WBC count does not necessarily signify infection or inflammation; it can also occur under stress-related conditions—for example, after vigorous exercise (e.g., running a lap) or during states of intense fear or anxiety.
1. Infection
Elevated white blood cell (WBC) count in clinical settings—such as when accompanied by fever—may indicate an infection. This is commonly referred to as an inflammatory response, which clinically manifests primarily through two key signs: (1) elevated WBC count and (2) fever.
2. Stress Response
However, an elevated WBC count does not necessarily indicate infection or inflammation. For instance, physiological stress—such as after vigorous exercise, intense fear, or severe anxiety—can also trigger a transient, stress-induced rise in WBC count. Nevertheless, clinically significant WBC elevation typically reflects an underlying inflammatory process.
Differentiating Types of Infection:
To differentiate infection types and determine etiology, consider the following: In bacterial infections, total WBC count typically increases. WBCs are further classified into subtypes—including neutrophils, lymphocytes, eosinophils, basophils, and monocytes. Clinically, neutrophils and lymphocytes are most frequently assessed. In bacterial infections, both total WBC count and the neutrophil percentage are usually elevated. In contrast, most viral infections are associated with decreased total WBC count, reduced neutrophil percentage, and increased lymphocyte percentage.
