Bacterial infections Biomarker
Collection Type: Blood
Related System: Bacterial infections
Helicobacter pylori Abs. (IgM) measures circulating IgM-class antibodies directed against H. pylori, a bacterium that infects the stomach lining. IgM is an early antibody isotype that rises soon after exposure and suggests recent or acute infection. The test helps evaluate suspected H. pylori–associated gastritis, peptic ulcer disease, dyspepsia, unexplained upper abdominal pain, nausea or recurrent vomiting. Seroprevalence increases with age and varies by geography and socioeconomic status; children and young adults are less likely to have longstanding IgG seropositivity, while older adults more often show past exposure. Immune status (immunosuppression) and prior eradication therapy affect results.
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Q: What does H. pylori IgM positive mean?
A: A Helicobacter pylori IgM positive result usually indicates recent or acute exposure, since IgM antibodies appear early in infection. It isn’t definitive alone—IgM tests can yield false positives or be less specific—so clinicians confirm with stool antigen, urea breath testing, or endoscopy/biopsy and correlate findings with symptoms before deciding on eradication therapy.
Q: What is a normal Helicobacter pylori antibody level?
A: Normal Helicobacter pylori antibody levels are those below the laboratory’s cutoff for a negative result. Many IgG assays use thresholds such as <10–20 units/mL (or an index <1.0) to indicate negative; values above the lab-specific positive cutoff (often ≥20–30 U/mL) suggest exposure. Serology cannot reliably distinguish active from past infection, so breath or stool tests confirm active infection.
Q: What does it mean when your IgM is positive?
A: A positive IgM means your immune system has recently produced early-stage antibodies to an infection, suggesting a current or recent (acute) exposure. IgM appears soon after infection but can give false positives or reflect recent vaccination or cross-reaction, so results must be interpreted with symptoms and other tests. Clinicians usually confirm with PCR or repeat serology (IgG, paired samples) before diagnosing.
Q: How is H. pylori IgM infection treated?
A: H. pylori infection is treated with combination antibiotic regimens plus a proton pump inhibitor (acid suppression). Common first-line is clarithromycin amoxicillin (or metronidazole) plus a PPI for 10–14 days. In areas with resistance or penicillin allergy, bismuth quadruple therapy (PPI bismuth tetracycline metronidazole) is used. Confirm eradication with a urea breath or stool antigen test ≥4 weeks after therapy.
Q: How long does H. pylori IgM remain positive?
A: H. pylori IgM appears early in acute infection and is usually transient. It typically becomes detectable within 1–2 weeks, peaks after a few weeks, and then declines over several weeks to about 2–3 months, often becoming undetectable thereafter. Because IgM is short‑lived, IgG or non‑serologic tests (breath, stool, biopsy) are preferred for longer‑term diagnosis or post‑treatment confirmation.
Q: Can H. pylori IgM indicate a recent infection?
A: H. pylori IgM alone is not a reliable marker of recent infection. IgM can appear early but is often transient and has limited sensitivity and specificity, leading to false positives or negatives. Accurate diagnosis and confirmation of active infection use urea breath tests, stool antigen tests, or endoscopic biopsy. IgG mainly shows past exposure, so confirmatory testing is recommended.