Does a normal stool calprotectin test rule out Helicobacter pylori-related inflammation?

A normal fecal calprotectin result should not be used to dismiss Helicobacter pylori infection or H. pylori–associated gastritis in this 50-year-old man. It is principally an intestinal inflammation marker, not an H. pylori diagnostic test.

Clinical evidence

• Adult chronic-gastritis data found no significant fecal calprotectin differences by H. pylori status, gastritis activity, or neutrophil-infiltration grade.
• In pediatric data, discrimination was poor for H. pylori (AUC 0.602) and only modest for gastritis (AUC 0.639). A proposed gastritis threshold had 64% sensitivity and 65% specificity—performance that allows clinically important false-negative results.
• Professional guidance does not recommend fecal calprotectin to diagnose or monitor H. pylori–related disease. When suspicion remains, H. pylori–specific testing is required rather than inference from calprotectin.

Mechanistic interpretation

• Calprotectin is abundant in neutrophils. During intestinal mucosal inflammation, neutrophils enter the mucosa and lumen, release calprotectin, and its stable stool concentration broadly reflects this inflammatory influx.
• Thus, substantial intestinal—often clinically relevant colonic—neutrophilic inflammation tends to elevate fecal calprotectin. A low value makes active inflammatory bowel disease less likely, but does not replace clinical assessment or endoscopy when warranted.
• Localized gastric inflammation may produce little or no stool signal, but this contrast is not absolute: gastritis and H. pylori infection can sometimes raise calprotectin, and elevation is not proof of colonic disease.

Bottom line

• Normal fecal calprotectin does not exclude H. pylori gastritis. The core rationale is sound—localized gastric disease is less consistently detected than intestinal neutrophilic inflammation—although calprotectin should not be viewed as exclusively colonic or as a definitive anatomical localizer.