The hydrogen breath test was developed to evaluate carbohydrate absorption. It also is used to aid in the diagnosis of bacterial over-growth in the intestine and short bowel syndrome. This test de-termines the amount of hydrogen expelled in the breath after it has been produced in the colon (on contact of galactose with fer-menting bacteria) and absorbed into the blood.
Urea breath tests detect the presence of Helicobacter pylori, thebacteria that can live in the mucosal lining of the stomach and cause peptic ulcer disease. The patient takes a capsule of carbon-labeled urea and then provides a breath sample 10 to 20 minutes later. Because H. pylori metabolizes urea rapidly, the labeled car-bon is absorbed quickly; it can then be measured as carbon diox-ide in the expired breath to determine whether H. pylori is present. The patient is instructed to avoid antibiotics or loperamide (Pepto-Bismol) for 1 month before the test; sucralfate (Carafate) and omeprazole (Prilosec) for 1 week before the test; and cimeti-dine (Tagamet), famotidine (Pepcid), ranitidine (Zantac), and nizatidine (Axid) for 24 hours before urea breath testing. H. pylori also can be detected by assessing serum antibody levels.