Helicobacter Pylori Serology Screen (H. Pylori Antibody [ IgG, IgA, and IgM] Screen)

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Subject: Helicobacter Pylori Serology Screen (H. Pylori Antibody [ IgG, IgA, and IgM] Screen)

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Definition

  • H. pylori is a bacterium that is found in the stomach of about two thirds of the people in the world, although most infected people will never develop disease. H. pylori infection is a major risk factor for peptic ulcer disease. These bacteria are responsible for the large majority of gastric ulcers and upper duodenal ulcers. Research studies indicate that infection with H. pylori increases the risk of gastric cancer, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and possibly pancreatic cancer.

  • Normal range: Negative.

Use

  • Screening for H. pylori infection.

  • Laboratory-based serologic testing to detect H. pylori IgG antibodies is inexpensive and noninvasive. This is the predominant serologic test available for clinical use, and it is well suited to primary care practice. However, concerns over its accuracy have limited its use. Large studies have found that it has high sensitivity (90–100%) but variable specificity (76–96%); the accuracy has ranged from 83 to 98%.

  • Some studies found that IgA antibodies may detect cases that were negative by IgG testing. However, a number of studies have demonstrated that IgA testing is overall less sensitive and less specific than IgG testing. Some laboratories also offer IgM tests, which if elevated would indicate an acute infection. IgM assays have little or no role in clinical practice for the diagnosis or management of what is almost always a long-standing condition by the time H. pylori infection is considered.

Interpretation

  • Positive result: Indicates that H. pylori IgG antibodies were detected in the sample. The presence of IgG antibodies to H. pylori is an indication of previous exposure to the organism.

  • Negative result: Indicates that H. pylori IgG antibodies were not detected in the sample. Negative results by this test do not preclude recent primary infection.

Limitations

  • The ACG guidelines recommend that testing for H. pylori should be performed only if the clinician plans to offer treatment for positive results.

  • Testing is indicated in patients with active peptic ulcer disease, a past history of documented peptic ulcer, or gastric MALT lymphoma.

  • The test-and-treat strategy for H. pylori (i.e., test and treat if positive) is a proven management strategy for patients with uninvestigated dyspepsia who are younger than 55 years of age and have no “alarm features” (bleeding, anemia, early satiety, unexplained weight loss, progressive dysphagia, odynophagia, recurrent vomiting, family history of GI cancer, previous esophagogastric malignancy).

  • Deciding which test to use in which situation relies heavily on whether a patient requires evaluation with upper endoscopy and an understanding of the strengths, weaknesses, and costs of the individual test.

  • General population screening of asymptomatic patients not recommended.

  • Patients with family history of GI cancer should have screening if symptomatic (endoscopy with biopsy).

  • Patients without “alarm” symptoms, a dyspepsia that does not respond to antireflux treatment, may be candidates for H. pylori testing.

 
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