Lactose intolerance: from diagnosis to correct management.

This review discusses one of the most relevant problems in gastrointestinal clinical practice: lactose intolerance. The role of lactase-persistence alleles the diagnosis of lactose malabsorption the development of lactose intolerance symptoms and its management. Most people are born with the ability to digest lactose, the major carbohydrate in milk and the main source of nutrition until weaning. Approximately, 75% of the world's population loses this ability at some point, while others can digest lactose into adulthood. Symptoms of lactose intolerance include abdominal pain, bloating, flatulence and diarrhea with a considerable intraindividual and interindividual variability in the severity. Diagnosis is most commonly performed by the non invasive lactose hydrogen breath test. Management of lactose intolerance consists of two possible clinical choice not mutually exclusive: alimentary restriction and drug therapy.

13C-Urea breath test for the diagnosis of Helicobacter pylori infection.

Helicobacter pylori (H. pylori) is a Gram-negative bacterium able to colonize the gastric mucosa as well as gastric metaplastic areas of the duodenum, producing inflammation. The clinical outcome depends on sophisticated interactions between bacterial factors, such as the expression of determinants of virulence and pathogenicity, and host characteristics. The severity of inflammation, may then vary among different subjects, leading to the occurrence of different gastroduodenal diseases, ranging from chronic gastritis to gastric cancer and MALT-lymphoma, to some defined extragastric manifestations. Many diagnostic tests are available for the detection of H. pylori infection including noninvasive methods, such as serology, (13)C-urea breath test (UBT), and fecal antigen tests and invasive techniques, including a combined use of endoscopic biopsy-based methods, such as rapid urease testing, histology, culture, and molecular methods. UBT is a highly sensitive and specific and allows to diagnose the presence or absence of infection of H. pylori, through the oral administration of a solution containing urea labelled with the non-radioactive natural carbon 13. This review article analyzes microbiological and clinical features of H. pylori as well as the different diagnostic tests able to detect this bacterium with a special focus on UBT.

Tricks for interpreting and making a good report on hydrogen and 13C breath tests.

Breath tests (BT) represent a valid and non-invasive diagnostic tool in many gastroenterological disorders. Their wide diffusion is due to the low cost, simplicity and reproducibility and their common indications include diagnosis of carbohydrate malabsorption, Helicobacter pylori infection, small bowel bacterial overgrowth, gastric emptying time and orocaecal transit time. The review deals with key points on methodology, which would influence the correct interpretation of the test and on a correct report. While a clear guideline is available for lactose and glucose breath tests, no gold standard is available for Sorbitol, Fructose or other H2 BTs. Orocaecal transit time (OCTT) defined as time between assumption of 10 g lactulose and a peak > 10 ppm over the baseline value, is a well-defined breath test. The possible value of lactulose as a diagnostic test for the diagnosis of small bowel bacterial overgrowth is still under debate. Among (13)C breath test, the best and well characterized is represented by the urea breath test. Well-defined protocols are available also for other (13)C tests, although a reimbursement for these tests is still not available. Critical points in breath testing include the patient preparation for test, type of substrate utilized, reading machines, time between when the test is performed and when the test is processed. Another crucial point involves clinical conclusions coming from each test. For example, even if lactulose could be utilized for diagnosing small bowel bacterial overgrowth, this indication should be only secondary to orocaecal transit time, and added into notes, as clinical guidelines are still uncertain.