Anxiety is a psychological state that can physically change blood test results. Neutrophils are white blood cells crucial to the immune system, and an elevated count (neutrophilia) is often found during routine lab work. This article explores the physiological mechanisms linking stress and anxiety to increased neutrophil counts.
Understanding Neutrophils and Neutrophilia
Neutrophils are the most abundant type of white blood cell. Produced continuously in the bone marrow, they circulate through the bloodstream to respond rapidly to foreign invaders. Their primary function is to locate, engulf, and destroy pathogens, particularly bacteria, through phagocytosis. They are also integral players in the body’s response to inflammation and tissue injury.
A blood test measures the Absolute Neutrophil Count (ANC), the total number of these cells found in a microliter of blood. For a healthy adult, the normal ANC typically ranges from 1,500 to 8,000 cells per microliter. Neutrophilia is the medical term used when this count rises above the established upper limit.
Neutrophilia is not a disease but a sign that the body is reacting to a stimulus. Most commonly, this elevation responds to an active bacterial infection or severe inflammation. The count can also be temporarily elevated by non-infectious factors, including intense physical exertion, trauma, or the physiological cascade triggered by acute or chronic stress.
The Body’s Response to Psychological Stress
Anxiety and stress initiate a complex physiological response designed to cope with a perceived threat. This reaction is orchestrated by the neuroendocrine system. When anxiety is perceived, the brain activates the Hypothalamic-Pituitary-Adrenal (HPA) axis, which manages the stress response.
Activation of the HPA axis leads to the secretion of glucocorticoids, primarily the stress hormone cortisol. Simultaneously, the sympathetic nervous system is stimulated, causing the rapid release of catecholamines, such as adrenaline and noradrenaline. This two-pronged hormonal release prepares the body for a “fight or flight” scenario.
Cortisol and catecholamines affect nearly every system, including the immune system. The release of these hormones shifts the body’s resources to address the perceived emergency. This hormonal surge causes a temporary redistribution of white blood cells, setting the stage for a measurable shift in neutrophil numbers during periods of high anxiety.
How Stress Hormones Mobilize Neutrophils
The link between psychological stress and high neutrophils is a specific physiological process known as demargination. Neutrophils exist in two populations: the circulating pool (measured in a blood test) and the marginal pool, where cells temporarily adhere to blood vessel walls. Marginal pool cells are not counted in a standard lab sample.
Cortisol, the primary stress hormone, acts on neutrophils by decreasing the expression of adhesion molecules, particularly L-selectin. These molecules allow neutrophils to stick loosely to the endothelial lining of blood vessels. By interfering with L-selectin, cortisol reduces the cell’s ability to remain tethered.
This loss of adhesion causes marginal pool neutrophils to detach and “demarginate,” forcing them into the circulating bloodstream. The result is an increased neutrophil count without the body producing new cells. This redistribution creates a temporary physiological neutrophilia that reflects cell movement rather than an active infection.
Stress hormones also contribute to the elevated count by slowing the process of apoptosis, or programmed cell death, in the neutrophils. Extending the lifespan of these circulating cells keeps the total number in the bloodstream higher for a longer period.
When to Rule Out Other Causes
Anxiety and psychological stress cause a measurable, mild to moderate, and temporary increase in neutrophils through demargination. Anyone with an elevated count must consult a physician, however, as more serious conditions are far more common causes of neutrophilia.
Bacterial infections trigger a true neutrophilia, stimulating the bone marrow to produce and release new cells, often resulting in much higher counts. A medical professional performs a differential diagnosis to distinguish between these possibilities.
Common Causes of Neutrophilia
Chronic inflammatory diseases, such as rheumatoid arthritis or inflammatory bowel disease, lead to sustained elevations as the body manages ongoing tissue damage. Certain medications, particularly corticosteroids, also cause neutrophilia because they mimic the effects of natural stress hormones like cortisol.
If the neutrophil count is very high or accompanied by physical symptoms like fever, localized pain, or other signs of infection, the cause is unlikely to be solely anxiety. The medical professional looks at the entire clinical picture, including health history, symptoms, and other blood markers, to determine the true underlying reason.