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  Hydrogen  2H / 1H
  Carbon  13C / 12C
  Nitrogen  15 / 14N
  Oxygen  18 / 16O
  Sulfur  34 / 32S


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Carbon-13 breath tests have been used in gastrointestinal research for many years as safe, simple and non-invasive methods of monitoring organ function and nutritional status. They have been employed in study of gastric emptying, liver function, fat absorption, P450 mixed-function oxidase, bacterial overgrowth, oro-caecal transit time, etc.

Iso-Analytical provides a comprehensive mass spectrometry service for carbon-13 breath test samples and also can offer help in experimental design and data interpretation.

In simple terms, carbon-13 breath tests involve the ingestion of a substrate (commonly used substrates include: acetate, caffeine, erythromycin, octanoic acid, urea, triglyceride or xylose) labeled on one or more functional groups with 13C. These 13C labeled functional groups are cleaved from the rest of the substrate molecule by the action of specific enzymes. The functional groups then further oxide until 13C enriched CO2 is produced and excreted in breath and the 13C:12C ratio in serially collected breath samples is measured by isotope ratio mass spectrometry. See Example Laboratory Report for 13C-Urea breath tests to detect Helicobacter pylori infection.

Liver Function Breath Tests

Historically, blood tests and scoring indexes have been employed to identify and monitor patients with liver disease. These tests reflect end point hepatocellular damage but do not quantitate functional hepatic reserve. Thus whilst advanced liver disease can be diagnosed with confidence, early or marginal hepatic disease is poorly defined. To increase this definition a series of breath tests have been developed and refined over the last 20 years. Specific liver function breath tests targeted at exploring the functionality of cytosolic, microsomal and mitochondrial enzyme systems within the hepatocyte are available. These tests provide information on:

  • prediction of long term prognosis
  • monitoring the progression of liver disease
  • following the effects of a therapeutic regimen
  • decision in optimum transplant timing

Gastric Emptying Breath Tests

Breath tests offer an alternative to scintigraphic techniques for measuring gastric emptying. The rate of emptying can be determined with 13C labeled octanoate (solid food) or acetate (liquid meals). The safety of the carbon-13 breath test and the ability to use it repeatedly has meant that it has found favour by those wanting to assess the efficiency of new motility drugs.

Bacterial Overgrowth Breath Tests

The 13C-xylose breath test offers a diagnostic alternative to the microbiological analysis of jejunal fluid for the diagnosis of small bowel bacterial overgrowth. This test offers a practical way of serial testing a condition that is often persistent throughout life.

Oro-Caecal Transit Time Breath Tests

Lactose-[13C]-ureide has proven to be a reliable marker to follow oro-caecal transit time. The tracer resists the action of brushborder enzymes and is not metabolised until reaching the colonic bacteria.

Other Breath Tests

There are a number of other breath tests that are used in gastrointestinal research. These include:

  • 13C-Erythromycin breath test (cytochrome P450 1A4 activity)
  • 13C-Caffeine breath test (cytochrome P450 1A2 activity)
  • 13C-Urea breath test (Helicobacter pylori infection)
  • 13C-Mixed triglyceride breath test (pancreatic function)
  • 13C-Lactose digestion breath test (lactose intolerance)

For further information please contact us or use our quote form to obtain a costing.

13C Breath

Animal Tissue

Bone Collagen

Core Water

Doubly Labelled Water

Fruit Juice Sugar

Fruit Juice Water

Maple Syrup