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.