The sucrose breath test is a non-invasive diagnostic tool that assesses an individual’s ability to digest sucrose, a common dietary sugar. It measures specific gases in the breath to provide insights into how the digestive system processes sucrose. This straightforward procedure can be performed in a medical office or at home.
Purpose of the Sucrose Breath Test
The sucrose breath test detects sucrose malabsorption, also known as sucrose intolerance or Congenital Sucrase-Isomaltase Deficiency (CSID). This condition occurs when the small intestine lacks enough sucrase-isomaltase, an enzyme needed to break down sucrose into simpler sugars like glucose and fructose for absorption. When this enzyme is deficient, undigested sucrose travels to the large intestine, where gut bacteria ferment it. This fermentation can lead to gastrointestinal symptoms such as bloating, abdominal pain, excessive gas, and diarrhea.
How the Sucrose Breath Test Works
The scientific principle behind the sucrose breath test relies on the metabolic activity of gut bacteria. When sucrose is not properly digested in the small intestine, it moves into the large intestine. In the large intestine, bacteria ferment the unabsorbed sucrose, producing gases such as hydrogen and methane. Humans do not naturally produce these gases, so their presence in exhaled breath indicates bacterial fermentation of carbohydrates within the digestive tract.
After an overnight fast, the patient drinks a solution of sucrose dissolved in water. Breath samples are collected at regular intervals, every 30 to 40 minutes, over 90 minutes to three hours. These samples are analyzed in a laboratory to measure hydrogen and methane gas concentrations. An increase in these gas levels over time suggests sucrose is being fermented by bacteria, rather than properly digested and absorbed.
Understanding Your Test Results
Interpreting sucrose breath test results involves analyzing hydrogen and methane gas levels in breath samples over time. A baseline sample is collected before consuming the sucrose solution to establish initial gas levels. A positive result for sucrose malabsorption is indicated by a significant rise in hydrogen or methane levels above this baseline after ingesting the sucrose solution. For instance, a rise of 20 parts per million (ppm) or more in hydrogen, or 10-12 ppm or more in methane, within 90 minutes or at any point during the test, can suggest malabsorption.
An early peak in gas production within the first 60 to 90 minutes points to bacterial fermentation in the small intestine. If gas levels remain low throughout the test, it indicates proper sucrose digestion and absorption, suggesting a negative result for sucrose malabsorption. However, a small percentage of people (15% to 30%) may not produce significant hydrogen or methane, even with malabsorption, because their gut flora converts hydrogen into other gases. Always discuss your specific results with a healthcare professional, as they consider individual factors and other clinical information for an accurate diagnosis and appropriate next steps.
Preparing for the Test and Next Steps
Proper preparation is important for accurate sucrose breath test results. Patients are advised to follow a specific low-carbohydrate diet for 12 to 24 hours before the test to minimize gas production from other food sources. This diet includes plain meat, white rice, eggs, and clear broths, while avoiding high-fiber foods, dairy, fruits, and certain vegetables. A fasting period of at least 8 to 12 hours is also required before the test, with only water permitted.
Patients should avoid certain medications for a specified period before the test, including antibiotics for four weeks and laxatives or promotility drugs for one week. Smoking or vaping should also be avoided for at least 24 hours prior to and during the test. Strenuous exercise or sleeping should be avoided for at least an hour before and during the test. Once results are available, a healthcare provider will interpret them and discuss potential diagnoses and management strategies, which might include dietary adjustments or other medical interventions.