Helicobacter pylori Antigen
Clinical Use
| • | Differential diagnosis of patients with peptic ulcer disease and chronic active gastritis |
| • | Therapeutic monitoring and documentation of cure in patients with H pylori infection |
Clinical Background
H pylori is associated very strongly with peptic ulcer disease (duodenal and gastric) and chronic active gastritis. H pylori is also an independent risk factor for gastric cancer and primary malignant lymphoma of the stomach. The infection can be treated successfully with a combination of 3 drugs for 10 to 14 days.
Four methods can be used to diagnose H pylori:
- Upper GI tract biopsy, microscopic exam, rapid urease testing, culture
- Urea breath test employing 14C or 13C-urea
- Antibody detection
- Antigen detection
This method detects H pylori antigen in stool specimens and can be used for diagnosis or therapeutic monitoring.
Method
The enzyme immunoassay employs monoclonal anti-H pylori capture antibodies adsorbed to microwells and peroxidase-conjugated monoclonal anti-H pylori detection antibodies. Based on the intensity of color developed, results are reported as H pylori antigen not detected or detected.
Performance characteristics have not been established for watery stools and for asymptomatic patients.
CPT Code*: 87338
Interpretive Information
A positive result (antigen detected) is indicative of H pylori presence (96% sensitivity); however some individuals may have H pylori antigen but no disease.
A negative result (antigen not detected) indicates absence of H pylori or an antigenic level below the assay limit of detection (184 ng H pylori protein/mL of stool) (95.7% specificity). False negative results may be obtained on specimens from patients who have ingested selected compounds (antimicrobials, proton pump inhibitors, bismuth preparations) within 2 weeks prior to specimen collection. Physicians may suggest the patient go off medications for two weeks and repeat the test. Positive results are valid in the presence of medications. In populations with disease prevalence ranging from 34% to 69% (average 52%), the positive and negative predictive values were 96%.
A positive result ≥7 days post therapy is indicative of treatment failure.
A negative result ≥4 weeks post-therapy indicates eradication of the infection.
Specimen Requirements
1 gram frozen stool
Collect 0.5 mL of liquid/semi-solid stool or 20 mm diameter solid stool and transfer to a properly labeled, sterile, leak-proof container. Do not place stool in preservative, transport media or swab. Watery, diarrheal stool is not acceptable.
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* The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.
