Can vomiting cause neutrophilia?

Can Vomiting Cause Neutrophilia?

Yes, vomiting can cause neutrophilia, particularly in the context of acute food protein-induced enterocolitis syndrome (FPIES), where an increased neutrophil count of ≥1500 neutrophils above baseline is recognized as a minor diagnostic criterion during acute reactions.

Evidence from FPIES Guidelines

The most direct evidence comes from the 2017 international consensus guidelines on FPIES 1. During acute FPIES reactions, which are characterized by severe vomiting occurring 1-4 hours after food ingestion, an increased neutrophil count of ≥1500 neutrophils above baseline is specifically listed as one of the minor diagnostic criteria for confirming the diagnosis during oral food challenges.

Key Clinical Context

In acute FPIES presentations, the neutrophilia occurs alongside:

• Repetitive vomiting (major criterion)
• Lethargy and pallor
• Subsequent diarrhea (typically 5-10 hours post-ingestion)
• Potential hypotension and hypothermia
• Complete symptom resolution within hours (distinguishing it from viral gastroenteritis)

The guidelines note that in chronic FPIES, patients demonstrate "an increased white blood cell count with a left shift and eosinophilia," which frequently leads to sepsis evaluations in emergency departments 1.

Mechanism and Clinical Significance

The neutrophilia in vomiting-associated conditions appears to reflect:

1. Acute inflammatory response to the underlying trigger (in FPIES, a non-IgE-mediated food reaction)
2. Stress demargination of neutrophils during acute physiologic stress
3. Hemodynamic shifts that can accompany severe vomiting episodes

Important Caveats

The neutrophilia is not caused by vomiting per se, but rather by the underlying inflammatory or infectious process causing the vomiting. The distinction is critical:

• In FPIES, the neutrophilia reflects the immune-mediated inflammatory cascade triggered by the offending food
• In other contexts (infection, inflammation, metabolic disorders), vomiting and neutrophilia may coexist as parallel manifestations of the same underlying pathology 2, 3

Clinical Pitfalls to Avoid

1. Don't assume all vomiting causes neutrophilia - isolated vomiting from benign causes (motion sickness, mild gastroenteritis) typically does not produce significant neutrophilia
2. Consider the temporal relationship - in FPIES, neutrophil counts are assessed 3 hours after food challenge, indicating the inflammatory response develops acutely
3. Evaluate for toxic changes - when neutrophilia accompanies vomiting with fever, dehydration, or systemic illness, examine the blood smear for toxic neutrophil changes suggesting serious infection or inflammation 2

Differential Diagnosis

When encountering neutrophilia with vomiting, consider:

• FPIES (especially in infants/young children with food triggers)
• Bacterial infection (gastroenteritis, peritonitis, sepsis)
• Inflammatory conditions (pancreatitis, cholecystitis)
• Metabolic derangements (diabetic ketoacidosis)
• Medication effects (chemotherapy-related, corticosteroids)

The presence of neutrophilia with vomiting should prompt investigation for these more serious underlying conditions rather than attributing both findings to a simple viral illness.