Understanding SIBO Breath Test: Labcorp Test Codes and Procedure Guide

Small Intestinal Bacterial Overgrowth (SIBO) affects millions of Americans, yet many struggle with proper diagnosis. The SIBO breath test has emerged as a valuable diagnostic tool, helping practitioners identify bacterial imbalances in the small intestine. If your healthcare provider has recommended this test through Labcorp, understanding the process and test codes can make your experience smoother and more efficient.

What is SIBO and Why Test for It?

SIBO occurs when excessive bacteria colonize the small intestine—an area that should have relatively low bacterial counts compared to the colon. This overgrowth can lead to uncomfortable symptoms including bloating, gas, abdominal pain, diarrhea, constipation, and nutrient malabsorption issues.

Testing for SIBO is crucial because its symptoms often overlap with other digestive disorders like IBS, making accurate diagnosis challenging without objective testing. The breath test measures gases produced by bacteria in your digestive system, providing valuable diagnostic information that guides treatment decisions.

Common Symptoms That May Warrant Testing

If you're experiencing persistent digestive discomfort, your healthcare provider might recommend a SIBO breath test. Key symptoms that often prompt testing include chronic bloating that worsens after meals, unpredictable bowel habits, unexplained weight loss, nutrient deficiencies despite adequate diet, and digestive discomfort that hasn't responded to other interventions. Many patients report that certain foods, particularly those high in fermentable carbohydrates, trigger or worsen their symptoms.

For those with FODMAP sensitivity, digestive symptoms can be particularly challenging to manage. Some find relief through specialized digestive enzyme supplements like those offered by Casa de Sante, which are specifically formulated with alpha-galactosidase and other enzymes to support FODMAP digestion. However, proper testing remains essential for accurate diagnosis and treatment planning.

How the SIBO Breath Test Works

The SIBO breath test is non-invasive and measures hydrogen and methane gases in your breath after consuming a test substrate. These gases are produced when bacteria ferment carbohydrates in your digestive system. In a healthy individual, this fermentation primarily occurs in the large intestine. However, with SIBO, fermentation happens prematurely in the small intestine, leading to earlier and higher gas measurements.

The test typically uses either glucose or lactulose as the test substrate. Glucose is absorbed in the first part of the small intestine, making it useful for detecting SIBO in the proximal (upper) small intestine. Lactulose passes through the entire small intestine before reaching the colon, potentially identifying SIBO throughout the small intestine, though it may have higher false positive rates.

Hydrogen vs. Hydrogen-Methane Testing

Modern SIBO testing measures both hydrogen and methane gases, which is important because different bacterial populations produce different gases. Some patients have methane-predominant SIBO (now often called intestinal methanogen overgrowth or IMO), which may present with different symptoms—typically constipation rather than diarrhea.

The dual-gas testing provides a more comprehensive picture of the bacterial environment in your intestines. Some labs now also test for hydrogen sulfide, another gas produced by certain gut bacteria that may contribute to digestive symptoms.

The Testing Process

During the test, you'll provide a baseline breath sample, then drink a solution containing the test substrate (glucose or lactulose). You'll then provide breath samples at regular intervals—typically every 20-30 minutes—for 2-3 hours. These samples are analyzed for hydrogen and methane content, creating a graph that shows how gas levels change over time.

A positive test typically shows an early rise in gas levels, indicating bacterial fermentation occurring in the small intestine rather than the colon. The specific patterns and gas levels help clinicians determine not only if SIBO is present but also its severity and predominant gas type.

Labcorp SIBO Test Codes and Options

Labcorp offers several breath test options for SIBO diagnosis. Understanding the specific test codes can help ensure you receive the appropriate test as recommended by your healthcare provider.

The most common Labcorp test codes for SIBO breath testing include:

Glucose Breath Test (Test Code 180085)

This test uses glucose as the substrate and measures both hydrogen and methane gases. It's particularly effective for detecting SIBO in the upper portion of the small intestine. The glucose breath test typically runs for 2 hours, with samples collected every 20 minutes.

Because glucose is normally absorbed in the proximal small intestine, any significant rise in breath gases within the first 90 minutes suggests bacterial overgrowth in the small intestine. This test has good specificity but may miss SIBO that occurs farther down in the small intestine.

Lactulose Breath Test (Test Code 180100)

The lactulose breath test also measures hydrogen and methane but uses lactulose as the substrate. Since humans cannot digest lactulose, it travels through the entire small intestine before reaching the colon. This makes it potentially more sensitive for detecting SIBO throughout the small intestine.

This test typically runs for 3 hours, with samples collected every 20-30 minutes. Interpretation requires careful analysis of the timing of gas rises to distinguish small intestinal bacterial fermentation from normal colonic fermentation.

Preparing for Your SIBO Breath Test

Proper preparation is crucial for accurate SIBO breath test results. Following the preparation instructions precisely helps minimize false positives or negatives. Your healthcare provider or Labcorp will provide specific instructions, but standard preparation typically includes:

Dietary Restrictions

For 24 hours before the test, you'll need to follow a specific low-fermentation diet. This typically means avoiding high-fiber foods, whole grains, fruits, vegetables, legumes, dairy products, and alcohol. Most protocols recommend a simple diet of plain protein (like chicken or fish), white rice, and minimal fats.

The evening before the test, you'll typically have a light dinner before beginning a 12-hour fast. During this preparation period, many patients with sensitive digestion find that digestive enzymes can help manage any discomfort from dietary changes. Professional-grade enzyme complexes that contain multiple enzymes—like those that include proteases for protein digestion, amylase for carbohydrates, and lipase for fats—can be particularly supportive during this transition period.

Medication and Supplement Restrictions

You'll need to avoid certain medications and supplements before the test, including:

- Antibiotics (typically for 2-4 weeks before testing)
- Probiotics (for 1-2 weeks before)
- Prokinetics and motility agents (for 1-3 days before)
- Laxatives and antidiarrheal medications (for 1 week before)
- Digestive enzymes (usually for 2-3 days before)

Always consult with your healthcare provider before stopping any prescribed medications. Some medications may be necessary to continue despite testing.

Morning of the Test

On the morning of your test, continue fasting from food and beverages other than water. Avoid smoking, sleeping, or exercising vigorously for at least 1 hour before the test begins. Brushing your teeth is permitted, but avoid swallowing any toothpaste or using mouthwash that contains alcohol.

Arrive at the testing location well-hydrated but having consumed only water. The testing process will take 2-3 hours, so plan accordingly.

Interpreting Your SIBO Breath Test Results

After completing your breath test, the samples will be analyzed and results typically become available within 1-2 weeks. Your healthcare provider will interpret these results in the context of your symptoms and medical history.

While interpretation criteria can vary slightly between laboratories, general guidelines exist for positive results:

Understanding Positive Results

For hydrogen breath tests, a rise of ≥20 parts per million (ppm) above baseline within the testing period is typically considered positive. For methane, a level of ≥10 ppm at any point during the test is often considered positive for methanogen overgrowth.

The timing of gas rises is also important. An early rise (within 90 minutes) suggests SIBO, while later rises may represent normal colonic fermentation. Some practitioners also look at the pattern and magnitude of gas production to assess severity and guide treatment approaches.

Treatment Approaches Following Diagnosis

If your breath test confirms SIBO, your healthcare provider will develop a treatment plan tailored to your specific situation. Treatment typically involves addressing the bacterial overgrowth directly while also working to resolve underlying causes that may have contributed to SIBO development.

Common treatment approaches include targeted antimicrobial therapy (prescription antibiotics or herbal antimicrobials), dietary modifications, and addressing motility issues. Many practitioners use a comprehensive approach that combines multiple strategies.

Supportive Strategies During Treatment

During SIBO treatment, digestive support can be valuable for managing symptoms and optimizing nutrient absorption. High-quality digestive enzymes, like Casa de Sante's professional-grade enzyme complex, can play a supportive role by helping break down proteins, carbohydrates, and fats more efficiently, potentially reducing the fermentation load in the small intestine.

Their comprehensive formula includes 18 targeted enzymes, including dual protease complexes for protein digestion, amylase for carbohydrates, and specific enzymes like alpha-galactosidase that help with FODMAP digestion. For those with SIBO who often experience heightened sensitivity to FODMAPs, these low FODMAP certified enzymes can provide meaningful digestive support while working through treatment protocols.

Remember that SIBO treatment is often a process rather than a one-time intervention. Many patients require multiple treatment cycles or ongoing management strategies to maintain digestive health. Working closely with your healthcare provider throughout this process ensures the most effective approach for your specific situation.

Conclusion

The SIBO breath test through Labcorp provides valuable diagnostic information that can guide effective treatment for this common but often overlooked condition. By understanding the testing process, proper preparation, and what your results mean, you can take an active role in addressing your digestive health.

If you're experiencing persistent digestive symptoms, discuss with your healthcare provider whether SIBO testing might be appropriate for your situation. With proper diagnosis and targeted treatment, many people find significant relief from the challenging symptoms of small intestinal bacterial overgrowth.