Helicobacter Pylori Tests: What Affects The Test

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What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include the following:

• The radioactive urea breath test for H. pylori is not usually done during pregnancy or while you are breast-feeding, because the radiation could harm your child.
• Use of antibiotics may affect the results of the urea breath test, the stool antigen test, and stomach biopsy by reducing the number of H. pylori bacteria in the stomach and duodenum.
• The use of lansoprazole (Prevacid), rabeprazole (Aciphex), sucralfate (Carafate), omeprazole (Prilosec), famotidine (Pepcid AC), ranitidine (Zantac), nizatidine (Axid), cimetidine (Tagamet), or medicines containing bismuth (such as Pepto-Bismol) can also interfere with the results of the urea breath test and stomach biopsy.
• A stomach biopsy may not detect an H. pylori infection that is present if the biopsy samples are taken from areas that are not infected by the H. pylori bacteria.
• Rough handling, contamination, or inadequate refrigeration of the blood sample can cause inaccurate blood antibody test results.
• When a blood antibody test is done early in an H. pylori infection, the results may be falsely negative because the level of antibodies is too low to measure.
• The likelihood of infection with H. pylori increases with age; older adults are more likely to have detectable amounts of the bacteria in their body.

Last updated:	January 11, 2008
Author:	Monica Rhodes
Reviewed By:	Kathleen Romito, MD - Family Medicine, Andrew H. Soll, MD - Gastroenterology
Editors:	Kathleen M. Ariss, MS, Pat Truman, MATC