Hydrogen Breath Test (Lactose/Glucose/Fructose)
This leaflet has been written by staff working in the Endoscopy Unit at Chelsea and Westminster Hospital.
We hope you find it useful. If, after you have read it, you have any questions or concerns, please ring us on our direct line 020 3315 3056/5223.
When you come into the Unit (2nd Floor, Lift Bank B), please talk to us about any worries and ask any questions you have.
If you would like to change your appointment time or date, please contact the Endoscopy Unit booking team on 0203 315 4141/5984 or email us Chelwest.cwdiagnosticcentre.admin@nhs.net.
Your appointment time in Endoscopy is approximate because some procedures may take longer than expected and emergency procedures need to take priority. Please expect to be in the department for several hours – having pre-procedure checks, the procedure and for recovery after the procedure.
What is a hydrogen breath test (lactose/glucose)?
A hydrogen breath test is used to diagnose two conditions:
- An overgrowth of bacteria in the small bowel (gut)
- A condition in which dietary sugars are not digested normally such as milk sugar (lactose) or fruit sugar (fructose).
These conditions may cause abdominal pain, bloating, gas and diarrhoea.
The test involves blowing into a machine through a small tube.
After a first sample has been taken, you will be asked to drink a sugary solution. Some people find that this mixture makes them feel a bit nauseous.
Further breath samples will then be collected in the same way as the first one.
To check for bacterial overgrowth we obtain samples every 15 minutes for 90 minutes.
To check for Lactose or Fructose intolerance we obtain samples every 15 minutes for the first 30 minutes and then every 30 minutes for the next hour.
The whole test will last approximately 2–3 hours and it is completely safe and painless.
How do I prepare for the test?
To ensure you will be able to have your test on the day, please follow these instructions:
- Do not eat any slowly digested foods (such as beans, bran and high-fibre cereals) for 24 hours prior to the test.
- Stop taking fibre supplements and laxatives 24 hours before the test.
- Do not eat or drink anything (including water) for 12 hours before the procedure. If you need to take medicine, take it only with a small sip of water at the usual time.
- Do not smoke, sleep or exercise for at least 30 minutes before or at any time during the examination, as this may affect the results of the test.
- Try to avoid places where people are smoking on the day of your test because second hand smoke can also affect the results of the test.
Please inform a member of staff if:
- You had any recent episodes of diarrhoea as this may give a false reading.
- You have just had a colonoscopy because you will need to wait 2–4 weeks after the colonoscopy before this test can be performed.
- You are pregnant, have a lung or heart condition, have any diseases, or if you are allergic to any medications.
Drugs
Do not take antibiotics for four weeks before the test. Take only the medications approved by your doctor before your test. Do not discontinue any medication without first consulting with your doctor.
Pregnancy and breastfeeding
Performing the breath test during pregnancy and breastfeeding has no damaging effects.
Driving and using machinery
The test has no influence on your ability to drive or to use machinery.
If you are diabetic
As you have diabetes, you are at an increased risk of developing a low level of blood sugar when you do not eat for a prolonged period, called a ‘hypo’, which may produce sweating, shaking, and blurred vision.
To avoid this occurring while you are preparing for your test, please inform a member of staff if you are diabetic.
After the test
You may resume your normal activities. You can restart your normal diet unless you have other tests that require dietary restrictions.
The result of the test will be forwarded to your GP. Your GP or referring clinician will contact you.