Project Description

Breath Test

Below are answers to many questions we frequently get asked. If you need more information, please get in touch with the Functional Gut Diagnostics team.

  • How can I order kits for the breath tests offered by Commonwealth Laboratories?

    The kits are provided at no cost to physicians and other health care providers. Of our more than 500 customers, many take advantage of our automatic ship programme, based on average monthly usage.

    • Call our office
    • Download the order form and fax back to us
    • Fill out our online order form
  • Where will my patients take the test?

    Patients will take the test in their homes. Simply have them leave your office with one of our consigned test kits. Your office will fill out the one page patient lab requisition form and send in via our HIPPA compliant e-fax line. Commonwealth Laboratories will do the rest.

  • How are the kits returned to Commonwealth Laboratories?

    We provide a pre-paid, pre-addressed UPS shipping label in each kit.

  • What is the turnaround time for breath test results?

    When the kit arrives at our laboratory, it will be analysed within 24 hours. Results will be sent via secure fax to your office, or set up and account and receive them via our HIPPA compliant web based reporting system..

  • How is insurance billing handled?

    We will bill the medical insurance provider indicated on the patient’s information/demographic sheet. Medicare, Medicaid and most medical insurance providers cover the cost of the breath test.

  • Do patients need a pre-authorisation before taking the test?

    This depends on the patient’s health plan. Even within the same medical health insurance company, some plans require pre-authorisation and others do not. It is best for the patient to contact the appropriate health insurance representative to enquire about pre-authorisation. As this is a specialty test performed by very few laboratories, most insurers have no in-network laboratory that provides this testing. This may need to be an out-of network pre-authorisation referral. If there is a pre-authorisation number, please ask the patient to write it on the information form he/she will be sending to us with the breath samples.

  • What if the patient doesn’t have medical insurance?

    If your patient has no medical insurance, ask him/her to call our office for information. We work with patients individually to determine a payment plan that will be appropriate.

Interpretation of Results

Q: What does it mean when all values are low with one spike?

A: Hydrogen: Breathing two or three times before collecting the sample can cause this.

A: Methane: This is common; methane diffuses quickly which can cause this to happen.

Q: What does it mean when the values are all zeros (or all twos etc.)?

A: This is very common. Up to 5% of all SIBO tests are ‘‘flatliners’’

A: This can either be caused by levels of hydrogen sulfide or methane below our detection limits.

Q: What do high values throughout the test mean?

A: Hydrogen: Poor preparation or a condition such as gastroparesis.

A: Methane: This is Normal

Q: What does it mean when there is a high baseline followed by decreasing values?

A: Poor test preparation.

Q: What do low values followed by a peak at #6 or #7 mean?

A: This can be due to a faster transit time than our test cut-off time.

A: Because the average start of colonic activity is around 105 minutes.

Medications and Procedure Questions

Q: Which medications will affect the outcome of a hydrogen breath test?

A: PPIs (Proton Pump Inhibitors such as Prilosec, Nexium, and Prevacid)

If the patient has been on a PPI for a while (a few months), the patient may stay on themedication and leave a note listing the medication in his/her kit when it’s sent back.

If the patient takes it as needed or just started the medication, he/she should be off themedication for the preparation period and the day of the test.

A: H2 Blockers (such as Zantac, Pepcid, Tagamet)

If the patient has been on H2 blockers for a while (a few months), the patient may stay on themedication and leave a note listing the medication in his/her kit when it’s sent back.

If the patient takes it as needed or just started the medication, he/she should be off themedication for the preparation period and the day of the test.

A: Narcotics

Do not take these the day of the test

A: Laxatives (such as Metamucil, Dulcolax, Ex-Lax)

Stop taking one day before taking test

A: Antibiotics

Stop taking 2 weeks before taking test

A: Probiotics

Stop taking 5 days before taking test

Q: Which procedures / conditions will affect the outcome of a test?

A: Colonoscopies

Must wait two weeks before taking test

A: Gastric Bypass surgery

Will accelerate transit time, leave note in test kit

A: Gastroparesis

Food will stay in stomach much longer, fermenting •May result in a high hydrogen baseline

Q: What about patients who have diabetes?

A: Patients with Type I: Basal insulin recommended no pre-meal insulin. Candy with sucrose/glucose can be used for low blood sugar levels. Only take Lactulose test.

A: Patients with Type II: Forgo medications day of test and start the test as early as possible in the morning.

Preparation Questions (Diet, Fasting, and Taking the Test)


Q: Can I use seasonings during the restricted diet?

A: Salt and Pepper may be used in moderation.

Q: Can I use cooking oil (olive oil, Pam etc.) during the restricted diet?

A: Yes, very small amounts of cooking oil are acceptable. The type of oil used isn’t as important as the amount of oil used.

Q: Can I chew gum during the preparation period?

A: No, gum is not allowed during any part of the preparation period.

Q: Can I smoke during the preparation period?

A: No, smoking should be stopped a few hours before the test.

Q: I forgot to follow the diet properly, will this affect my test?

A: Yes, improper diet will show up in the baseline sample of your test. Too high of a value usually means a retake is required.

Q: I did not fast for the full 12 hours, will this affect my test?

A: Yes it can. It could show a high baseline or inconsistent values throughout the test.

Q: I forgot to take the baseline sample, can I continue with the test?

A: It depends, if you remembered to take the baseline within 15 minutes of the substrate, continue as usual. Record the time when the substrate was ingested and continue with the recommended timing of the test. If it was longer than 30 minutes, the test must be redone.

Q: What happens if I vomited during the test?

A: If it was early on in the test (two or three tubes into the test), the test must be redone.

A: If it was after tube #3, you will be fine; include a note explaining in test kit.

Q: What if I have to run to the bathroom during the test?

A: Mark down the time and leave a note in the test kit. This will affect your overall results.

Q: I sipped the substrate throughout the test. Will the test still be accurate?

A: No, the test must be redone.


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

A: Very common. Up to 5% of all SIBO 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?

A: Glucose is a more specific substrate due to the fact that no human should be fermenting this substrate.

A: Lactulose gives a more complete picture of the intestinal tract, but 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 bacterial overgrowth testing, there is no way to calculate this value; however, patients with IBS have abnormal breath test results compared to normal, healthy patients by a factor of 10. If they have this abnormal breath test, they will also respond more favorably to antibiotic treatment.

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 SIBO 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.




Monday – Friday 8:00 – 17:00
Saturday 9:30 – 17:00
Sunday 9:30 – 15:00

  +44(0) 203 111111



Our team’s aim is to greatly improve the performance, delivery, analytical power and support for diagnostic services for patients with functional gastrointestinal disorders.

AMANDA BARLOWPractice Manager / Senior Administrator
PARDEEP RAISales & Technical Support
JENNIFER HAYNESTrainee Gas Chromatography Scientist & Clinical GI Physiologist

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