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Hydrogen Breath Testing

What is the hydrogen breath test?

The hydrogen breath test measures hydrogen gas in the breath and is used to diagnose several conditions that cause gastrointestinal symptoms. In humans, bacteria - specifically anaerobic bacteria in the colon - are capable of producing hydrogen. When bacteria is exposed to undigested sugars and carbohydrates, the bacteria produces hydrogen. Typically there is a limited amount of undigested sugars that reach the colon, but in certain conditions a lack of digestion leads to a large number of undigested carbohydrate in the colon and increased amounts of hydrogen gas may be produced.

Increased amounts of hydrogen gas also may be produced when the colon bacteria move back into the small intestine, a condition called small intestinal bacterial overgrowth or SIBO (alternatively small bowel bacterial overgrowth or SBBO). In this instance, the bacteria are exposed to unabsorbed food that has not yet had a chance to completely traverse the small intestine to be fully digested and absorbed.

Some of the hydrogen gas that is produced in the intestine is then absorbed into the blood via the walls of the intestines.  It travels to the lung where it is released, exhaled in the breath, then measured.

When is hydrogen breath testing used?

Hydrogen breath testing is used in the diagnosis of three conditions.  Since these different conditions may require different substrates for testing, a single breath test may not be able to diagnose all of these conditions.

  1. Abnormal Digestion of Dietary Sugars:  Dietary sugars are not digested normally. The most common sugar that is poorly digested is lactose, the sugar in milk. Individuals who are unable to properly digest lactose are referred to as lactose intolerant. Testing also may be used to diagnose problems with the digestion of other sugars such as sucrose, fructose and sorbitol.
  2. Small Intestinal Bacterial Overgrowth (SIBO):  a condition in which larger-than-normal numbers of colonic bacteria are present in the small intestine.  Glucose is typically used as the substrate in this case, but sometimes the diagnosis can be suggested using one of the above substrates.
  3. Rapid Small Bowel Transit Time: food moves rapidly through the small intestine, which may cause abdominal pain, abdominal bloating and distention, flatulence (passing gas in large amounts), and diarrhea.

How do I get ready for this test?

Thirty (30) Days Before Your Test

  • No antibiotics or antifungal medications (erythromycin for gastroparesis is allowed).

Fourteen (14) Days Before Your Test

  • No test that requires cleansing of the bowel, such as colonoscopy or barium enema.

Seven (7) Days Before Your Test

  • No fiber supplements such as Metamucil, Citrucel, Benefiber, psyllium, fiber gummies, fiber bars.
  • No probiotics. No Carafate. No Tums.
  • No laxatives or stool softeners such as lactulose, Miralax, Senna, Dulcolax, Milk of Magnesia, Pepto- Bismol, Colace, magnesium, or Smooth Move tea.
  • No antidiarrheal medications such as Lomotil, Imodium, Kaopectate.
  • No anti-gas medications such as Gas X or Simethicone. No enemas.

The Day Before Your Test

Consume Only:

  • White bread such as Wonder or Stroehmann (No Italian, French or sour dough or bagels)
  • White oyster crackers or white saltines. (For Gluten free - Good Thins Rice Simply Salt) No whole grain.
  • Plain steamed white rice
  • Fresh baked or broiled chicken, turkey or fish (No processed meat. No beef, goat, lamb or pork)
  • Boiled or microwaved egg
  • Water, weak black coffee or black tea-non flavored. No herbal teas.
  • Only salt and pepper may be used to flavor your food. (No butter, margarine, jelly, soda pop, juices, dairy, candy or gum)

DO NOT allow your child to EAT OR DRINK ANYTHING ELSE—it could give false results for the test.

All allowed foods need to be eaten in moderation.
To provide guidance: Protein serving: 3 ounces of meat or 1 egg. Carbohydrates: Rice serving 1 cup. Bread serving 1 slice. Saltine serving 5 crackers.
Can have 3 meals + 1 snack. For breakfast and lunch can have 2 protein servings and 1 serving for the evening meal and snack. 2 carbohydrate servings for each meal and the snack.


12 Hours Before Your Test

Your child must stop eating and drinking 12 hours before the test. Water is allowed.
For example, if the test is at 8:00 a.m., your child would stop eating and drinking at 8:00 p.m. the night before.


The Day of Your Test.

  • Your child may take prescription medications with water except those listed above.
  • Do brush the teeth but don’t swallow tooth paste. Rinse well with water.
  • Your child cannot eat, drink, chew gum, or have candy or mints.
  • Tobacco or cigarette smoke can interfere with the test so there should be no exposure.
  • No sleeping 1 hour before the test or during.
  • The test will last for at least three hours. Please allow sufficient time for completion of the test.
  • You may wish to bring a book and play items to occupy the child. Wireless internet is available.
  • If you have questions regarding the test or appointment, please call 585-275-2647.

The Test Procedure

  • A breath sample will be collected by having child exhale into a small device.
  • A 5 to 8-ounce solution will be given for child to drink.Child needs to drink this whole amount within 5 minutes.
  • Breath samples will be collected every 20-60 minutes.
  • During the test, take notice of symptoms and inform the technician if child has typical symptoms for which the test is being performed.
  • During the test, child should not eat, chew candy, sleep, exercise or be exposed to smoke.
  • When the test is over you may leave.No need to stop at check out.Usual diet and activity may be resumed after the test.
  • If you have not received results in a week then contact your doctor’s office to request the results.

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