FAQ: Miscellaneous

Q: How common are SIBO test results that are all zeros?

A: Very common. Up to 5% of all Small Intestinal Bacterial Overgrowth tests are all zeros.

Q: Can I take a SIBO test while pregnant?

A: Yes, but you should wait until you are not pregnant to perform the test. The test itself is safe, but no medication can be given if the result is positive.

Q: Which substrate should I use: glucose or lactulose?

  • A1: Glucose is a more specific substrate due to the fact that no human should be fermenting this substrate.
  • A2: Lactulose gives a more complete picture of the intestinal tract, but it also has a higher rate for false positives.

Q: What is the sensitivity/specificity of your SIBO test?

A: Since there is no gold standard for Small Intestinal Bacterial Overgrowth testing, there is no way to calculate this value; however, patients with Irritable Bowel Syndrome have abnormal breath test results compared to healthy patients by a factor of 10.

Q: What is the difference between the substrates glucose and lactulose?

A: Lactulose is a synthetic disaccharide that cannot be digested or absorbed by human cells. Many providers use lactulose when administering the breath test for Small Intestinal Bacterial Overgrowth as they feel it gives a complete profile of the small intestine and can identify distal overgrowth. Glucose is a simple monosaccharide. Some providers feel that the glucose substrate can be restrictive when doing a breath test for SIBO as it is absorbed very quickly and may only be able to identify overgrowth in the proximal region of the small intestine.

Contact our Customer Service department with questions (international toll-free) at 888-258-5966 or customerservice@commonwealthdx.com.