Can ulcerative proctitis cause elevated white blood cell (WBC) and neutrophil counts?

Elevated WBC and Neutrophil Counts in Ulcerative Proctitis

Yes, ulcerative proctitis can cause elevated white blood cell (WBC) counts and neutrophil levels due to the active inflammatory process occurring in the rectal mucosa.

Pathophysiology of Neutrophil Involvement in Ulcerative Proctitis

Ulcerative proctitis, a localized form of ulcerative colitis (UC) affecting only the rectum, is characterized by significant neutrophil infiltration in the intestinal mucosa. This process occurs through several mechanisms:

• Neutrophil recruitment: Inflammatory mediators in the colon of patients with active UC stimulate neutrophil migration to the site of inflammation 1
• Neutrophil activation: Once at the site, neutrophils become activated, releasing inflammatory proteins 1
• Delayed neutrophil apoptosis: The inflammatory environment in UC promotes prolonged neutrophil survival 1

Key Histological Features

The European consensus on histopathology of inflammatory bowel disease identifies several neutrophil-related findings in UC/proctitis 2:

• Cryptitis: Presence of neutrophils within crypt epithelium
• Crypt abscesses: Accumulation of neutrophils within crypt lumina
• Basal plasmacytosis: Plasma cells between the base of crypts and muscularis mucosae
• Neutrophilia: High number of neutrophils in the lamina propria

Laboratory Findings in Active Ulcerative Proctitis

According to the European consensus on diagnosis and management of UC, laboratory markers may reflect disease activity 2:

• Elevated WBC count: Can occur in active disease, particularly with significant inflammation
• Neutrophilia: Often present during active inflammation
• Thrombocytosis: May occur as part of the chronic inflammatory response
• Elevated CRP: Generally correlates with clinical severity in UC (except isolated proctitis)

It's important to note that laboratory markers of chronic inflammation may be normal in mild or moderate UC 2. Isolated proctitis may not always demonstrate elevated systemic inflammatory markers compared to more extensive colitis.

Clinical Significance of Neutrophil Markers

Neutrophil-derived proteins serve as important biomarkers in UC/proctitis 3, 4:

• Human Neutrophil Lipocalin (HNL): A specific marker of neutrophil inflammation in UC and proctitis
• Myeloperoxidase (MPO): Released during neutrophil activation
• Calprotectin: A robust neutrophil and disease activity biomarker

Studies have shown that mucosal release of neutrophil granule proteins like HNL and MPO can be increased 10-55 fold in patients with colitis and proctitis compared to controls 3.

Treatment Response and Neutrophil Parameters

The response to treatment in ulcerative proctitis correlates with changes in neutrophil parameters:

• In patients who respond to topical steroid treatment, concentrations of neutrophil-derived proteins decrease 5
• There is a close correlation between human neutrophil lipocalin concentrations and treatment response 5
• Steroid treatment partly neutralizes the factors that stimulate neutrophil migration, activation, and survival 1

Diagnostic Considerations

When evaluating elevated WBC and neutrophil counts in a patient with suspected ulcerative proctitis:

1. Exclude infectious causes: Stool specimens should be obtained to exclude common pathogens and specifically assayed for C. difficile toxin 2
2. Consider other inflammatory markers: CRP, ESR, and fecal calprotectin can help assess disease activity
3. Endoscopic evaluation with biopsies: Histopathological examination remains crucial for diagnosis

Pitfalls and Caveats

1. Not all patients with proctitis will show elevated systemic WBC: Laboratory markers may be normal in mild or moderate disease 2
2. Differential diagnosis: Elevated WBC with neutrophilia can occur in infectious colitis and other inflammatory conditions 6
3. Treatment effects: Medications, particularly corticosteroids, can alter WBC counts independently of disease activity 2
4. Isolated proctitis vs. extensive colitis: Systemic inflammatory markers may be less pronounced in isolated proctitis compared to extensive colitis

In conclusion, while ulcerative proctitis can cause elevated WBC and neutrophil counts due to active mucosal inflammation, these laboratory findings should be interpreted in the context of clinical presentation, endoscopic findings, and histopathology for accurate diagnosis and management.