Carbohydrate breath testing is a simple non-invasive test for carbohydrate malabsorption.
Breath testing was initially used to test for lactose malabsorption but it is now used to test for other carbohydrates.

At Frankston Private Diagnostic Unit (FPDU) we perform carbohydrate breath testing for fructose, lactose, sorbitol malabsorption as well as lactulose or glucose breath testing which is used to test for small intestinal bacterial overgrowth.


Basic principles of breath testing

When bacteria break down carbohydrates they produce acids, water and gases. The major gases produced are carbon dioxide (CO2) hydrogen (H2) and methane (CH4).

Only bacteria can produce H2 and CH4 Therefore if either of these gases is produced in the body it signals the breakdown of undigested carbohydrate in the intestine.

Why do we measure hydrogen and methane?

Breath testing equipment initially only measured breath hydrogen levels and the test is still often referred to as a hydrogen breath test. Some people do not produce hydrogen. If we were testing a non hydrogen producer with equipment which only tested hydrogen levels we could give a false negative result.
The addition of breath methane analysis increases the the ability to accurately diagnose carbohydrate malabsorption.

What is the preparation required?

The day prior to the appointment you must have a low residue diet. This is to prevent a possible false positive result from any residual carbohydrate metabolism.
You must fast 12 hours prior to the appointment.
Each test takes 3 hours. We can only test for one solution at a time.

How is the breath test performed?

A baseline pre -dose breath sample is taken and hydrogen and methane levels are measured.
You will be given a drink and breath samples will be collected and analyzed every 15or 30 minutes for 3 hours.

How are results interpreted?

A rise of either the hydrogen or methane level is considered positive ie we don’t need a positive reading for both gases
The results are explained to you and if the test is positive we provide you with information on how to change your diet.