Helicobacter pylori Antibody, IgG (Quantitative)
Code:17041
| Includes | Helicobacter pylori IgG antibody |
|---|
Analysis details
Methodology
- Enzyme-linked immunosorbent assay (ELISA)
Expected Turnaround Time
1–2 days
Special Instructions
- Avoid smoking for at least 30 minutes before the blood draw.
How to use
The quantitative anti–Helicobacter pylori IgG assay aids diagnosis of H. pylori infection associated with antral or fundal gastritis and peptic ulcer disease, especially when endoscopic testing is not planned. This H. pylori IgG serology can be compared before and after therapy to assess treatment response when a baseline value exists; antibody testing alone is not adequate to document eradication.
Limitations
Helicobacter pylori infection provokes both local mucosal and systemic immune responses. After a brief IgM rise, serum IgG—and often IgA—increase and remain elevated; IgG is detectable in approximately 95% to 100% of infected individuals, IgA in 68% to 80%, and IgM in 15% to 20%. Because serology reflects host antibody production rather than direct organism detection, diminished immune responsiveness in older adults or in patients receiving immunosuppressive therapy can produce false-negative results. In untreated patients, high IgG titers support recent or active infection. Following successful eradication, IgG frequently persists for many months, and about half of cured individuals maintain elevated IgG levels for 12 to 18 months. Consequently, a single positive IgG result after therapy cannot distinguish active from past infection and warrants additional testing. When pretreatment values are available, a 20% to 25% decline in IgG over 6 months is consistent with eradication, and loss of detectable IgG on repeat testing supports cure. Quantitative IgG results may also contribute to a serologic appraisal of gastric mucosal status.
| Reference interval |
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|---|---|---|---|---|---|
| Indications | Initial assessment of new dyspepsia in settings where endoscopy is not anticipated, Workup of dyspepsia in patients without prior Helicobacter pylori–targeted therapy and without exposure to antibiotics active against H. pylori, Primary diagnosis of Helicobacter pylori infection and re-evaluation about 6 months after eradication therapy to assess response |
Possible Causes of Abnormal Results
Decreased levels
- immunosuppression
- older age
Specimen Requirements
| Specimen | Serum |
|---|---|
| Container | Gold/Tiger Top (SST, Gel Separator) |
References
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