How to Measure Gastric Emptying Rates with a Stable Isotope Breath Test

How to Measure Gastric Emptying Rates with a Stable Isotope Breath Test

Diabetic gastroparesis is a debilitating form of neuropathy, i.e., nerve damage that affects the gastrointestinal tract.  Gastroparesis occurs when food moves too slowly through the digestive tract.  Symptoms of nausea, vomiting, bloating and abdominal pain results while eating meals.  Quality of life is severely impacted with the chronic condition of gastroparesis.  Approximately 12% of diabetics may experience gastroparesis.

Non-diabetics may also experience gastroparesis.  It is estimated that 4% of the general U.S. population may experience gastroparesis following meal ingestion.  There is a significant unmet medical need for upper GI therapeutics to treat this condition.

Metabolic Solutions has been leading the way for pharmaceutical companies to easily conduct research with novel promotility drugs.  An array of techniques are available for assessing gastric emptying rates including scintigraphy, ultrasonography, magnetic resonance imaging, wireless capsules, acetaminophen absorption and breath tests.  Scintigraphy is the gold standard to measure gastric emptying rates.  However, scintigraphy is very expensive, uses radioactivity that prevents multiple testing, and protocols can vary from center to center.

Breath tests can be utilized after either liquid or solid meals.  Gastroparesis is a problem of solid emptying.  The typical protocols measure solid emptying rates with 13C-octanoate or 13C-acetate breath tests.  A meal is covalently labeled with either of these two stable isotope tracers.  As the meal is processed in the stomach and passes through the pylorus, the octanoate or acetate is released into the small intestine.  Complete absorption is rapid with first-pass hepatic metabolism to 13CO2 that ultimately appears in the breath.  Breath 13CO2 is measured by stable isotope analysis validated methods.  Appearance of breath 13CO2 is directly proportional to gastric emptying rates.

The Gastric Motility Breath Test (GMBT) developed by Metabolic Solutions measures gastric emptying rates with a simple to prepare muffin meal.  A solution of stable isotope 13C-ocatanoate is added to the dry-powder mix, the contents stirred, and the mix is heated in a microwave for 2 minutes.  Breath samples collected before and after the meal ingestion are used to measure gastric emptying.  More information about the GMBT is found in our clinical site manual.

The accuracy of the breath testing to measure gastric emptying rates is well supported by several validation studies, for example Bromer et al. 2002.  The major advantages of the GMBT breath test are (1) all muffin meals are identical which reduces variability, (2) utilizing multiple breath tests in a short treatment window are possible, (3) studies can be conducted in any medical office.

Please contact us to set up a Gastric Emptying Breath Test protocol or to inquire about our stable isotope analysis services.