Breath Test / Basics

¹³C-LABELED SUBSTRATES

These tests are diagnostic tools that consider patient’s metabolic and physiologic properties to explore the existence of possible diseases or infections.

During the metabolization of the said substrates, carbon dioxide (CO₂) is the most common end product and that can more easily be measured. Therefore, the tests aim to determine the amount of ¹³C-carbon dioxide (¹³CO₂) and compare it to expired isotope ¹²CO₂.

In breath tests with ¹³C-labeled substrates, the isotopic ratio (¹²CO₂/¹³CO₂) always takes into account patient’s physiological characteristics (weight and mass) and kinetics of metabolism. Thus, we can determine certain organs conditions (pancreas, liver), metabolic disorders, infections, bacterial overgrowth or gastric emptying time.

NON-LABELED SUBSTRATES

Tests with non-labeled substrates are also known as hydrogen (H₂) / methane (CH₄).

Hydrogen and methane are produced in the digestive system essentially by the bacterial fermentation of carbohydrates (starches, sugars or vegetable fibers). If these gases appear in the expired air, it is usually because those carbohydrates have been exposed to bacteria.

The peculiarity of these tests is that carbohydrates are usually digested in the small intestine. If not, little fragments reach the colon, a region particularly rich in bacteria.

Therefore, these tests are used to determine gastric emptying time, bacterial overgrowth or to detect malabsoprtions of carbohydrates in the intestine.