Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Prior to hydrogen breath testing, the patient fasts for at least 12
hours. At the start of the test, the patient blows into and fills a balloon with
a breath of air. The concentration of hydrogen is measured in a sample of breath
removed from the balloon. The patient then ingests a small amount of the test
sugar (lactose, sucrose, sorbitol, fructose, lactulose, etc. depending on the
purpose of the test). Additional samples of breath are collected and analyzed
for hydrogen every 15 minutes for three and up to five hours.
How are the results of hydrogen breath testing
interpreted?
The interpretation of the results of hydrogen breath testing depends
on the sugar that is used for testing, and the pattern of hydrogen production
after the sugar is ingested.
After ingestion of test doses of the dietary sugars lactose, sucrose,
fructose or sorbitol, any production of hydrogen means that there has been a
problem with digestion or absorption of the test sugar and that some of the
sugar has reached the colon.
When rapid intestinal transit is present, the test dose of non-digestible
lactulose reaches the colon more quickly than normally, and, therefore, hydrogen
is produced by the colonic bacteria soon after the sugar is ingested.
When bacterial overgrowth of the small bowel is present, ingestion of
lactulose results in two separate periods during the test in which hydrogen is
produced, an earlier period caused by the bacteria in the small intestine and a
later one caused by the bacteria in the colon.
What are the limitations of hydrogen breath
testing?
There are several limitations to hydrogen breath testing. For unclear
reasons, testing for bacterial overgrowth of the small bowel with lactulose can
diagnose only 60% of cases. (This insensitivity of the test may be due in part
to the strict criteria that are used for interpreting a test as abnormal. Less
strict criteria may diagnose overgrowth more often.) In addition, with bacterial
overgrowth there may be an overlap of the early and later periods of hydrogen
production that can be misinterpreted as a single period characteristic of rapid
intestinal transit. Finally, some normal individuals may have slow transit
through the small intestine making prolonged testing - up to 5 hours -
necessary, and many individuals are unwilling to undergo such prolonged testing.
Some individuals do not have bacteria that produce hydrogen, and in these
individuals hydrogen breath testing is not possible. Most of these individuals
have bacteria that produce a different gas, methane. (There also are individuals
who produce both hydrogen and methane.) Methane can be measured in the breath
just like hydrogen, and the production of methane can be used for diagnosis in
the same way as hydrogen. There is much less experience with methane, however,
and the production of methane is more complex than the production of hydrogen.
Therefore, it is not clear if the pattern of methane production after ingestion
of sugars can be interpreted in the same way as hydrogen production,
particularly for the diagnosis of bacterial overgrowth.
A pattern of hydrogen production that is typical for bacterial overgrowth
does not necessarily mean that an individual's symptoms are caused by the
overgrowth. For example, there may be anatomic abnormalities of the small
intestine such as narrowing or functional abnormalities in the way the
muscle of the small intestine works. These abnormalities can cause symptoms
of bloating, distention, pain,
and diarrhea themselves, but they also can lead to bacterial overgrowth with its
similar symptoms. Therefore, it may be an underlying abnormality that is
responsible for the symptoms and not the bacterial overgrowth. The only way to
differentiate between the two causes of symptoms-an underlying problem or
bacterial overgrowth - is to treat and eradicate the bacteria. If the symptoms
disappear, then it is more likely that it is the overgrowth rather than the
underlying abnormality that is responsible for the symptoms.
Any condition that results in the delivery of undigested or unabsorbed food
to the colon may result in abnormal breath tests when dietary sugars are used
for testing. Both pancreatic
insufficiency and celiac sprue
can cause abnormal breath tests, in the former instance because pancreatic
enzymes that are necessary for the digestion of carbohydrates are missing,
and in the latter instance because the lining of the small intestine is
destroyed, and digested food cannot be absorbed. It may be necessary to exclude
these causes of abnormal breath tests by additional tests-pancreatic function
tests and small intestinal biopsy.
Abdominal pain is pain in the belly and can be acute or chronic. Causes include inflammation, distention of an organ, and loss of the blood supply to an organ. Abdominal pain can reflect a major problem with one of the organs in the abdomen such as the appendix, gallbladder, large and small intestine, pancreas, liver, colon, duodenum, and spleen.
Diarrhea is a change is the frequency and looseness of bowel movements. Cramping, abdominal pain, and the sensation of rectal urgency are all symptoms of diarrhea. Absorbents and anti-motility medications are used to treat diarrhea.
Gas or "intestinal gas" means different things to different people. Everyone has gas and eliminates it by belching or farting (passing it through the rectum).
Crohn's disease is a chronic inflammatory disease,
primarily involving the small and large intestine, but which can
affect other parts of the digestive system as well. Abdominal pain, diarrhea, vomiting, fever, and weight loss are
common symptoms.
In lactose intolerance, the digestive system cannot digest lactose (the main sugar in milk). Symptoms of lactose intolerance include diarrhea, flatulence, abdominal pain, abdominal bloating, abdominal distention, and nausea. There are several tests to diagnose lactose intolerance. Treatment is generally made with dietary changes, supplements, and adaptation to small amounts of milk.
IBS (irritable bowel syndrome) is a common gastrointestinal disorder involving abnormal gut contractions (motility) characterized by abdominal pain,
bloating, mucous in stools, and irregular bowel habits with alternating diarrhea
and constipation, symptoms that tend to be chronic and to wax and wane over the
years. Treatment options include medication and lifestyle changes such as diet, exercise, and stress management to control symptoms. Also called spastic colitis, mucus colitis, nervous colon syndrome.
Celiac disease is a result of an immune reaction to gluten, a protein found in wheat or related grains and present in many foods that we eat. Celiac disease causes impaired absorption and digestion of nutrients through the small intestine. Signs and symptoms of celiac disease include malabsorbption (diarrhea, foul smelling gas, bloating, and increased amounts of fat in the stool) and malnutrition (weight loss, edema, anemia, bruising easily, neuropathy, and infertility). Treatment for celiac disease is a gluten free diet, and at times if necessary, medications
Small intestinal bacterial overgrowth (SIBO) refers to a condition in which abnormally large numbers of bacteria (at least 100,000 bacteria per ml of fluid) are present in the small intestine and the types of bacteria in the small intestine resemble more the bacteria of the colon than the small intestine. There are many conditions associated with small intestinal bacterial overgrowth, to include: diabetes, scleroderma, Crohn's disease, and others. There is a striking similarity between the symptoms of irritable bowel syndrome and SIBO. It has been theorized that SIBO may be responsible for the symptoms of at least some patients with irritable bowel syndrome. Symptoms of SIBO include: excess gas, abdominal bloating, diarrhea, and abdominal pain.
Dyspepsia (indigestion) is a functional disease in which the gastrointestinal organs, primarily the stomach and first part of the small intestine, function abnormally. It is a chronic disease in which the symptoms fluctuate infrequency and intensity. Symptoms of dyspepsia include upper abdominal pain, belching, nausea, vomiting, abdominal bloating, early satiety, and abdominal distention (swelling). These symptoms are most often provoked by eating.
The inflammatory bowel diseases (IBD) are Crohn's disease (CD) and ulcerative colitis (UC). The intestinal complications of Crohn's disease and ulcerative colitis differ because of the characteristically dissimilar behaviors of the intestinal inflammation in these two diseases.
Digestion is the complex process of turning food you eat into the energy you need to survive. The digestive process also involves creating waste to be eliminated, and is made of a series of muscles that coordinate the movement of food.
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