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Reference Guide
Genova Diagnostics
SIBO - 3 Hour

SIBO - 3 Hour

Genova Diagnostics
SIBO - 3 Hour
Genova Diagnostics
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SIBO - 3 Hour
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About the Test

What is the SIBO 3-Hour Test?

The SIBO 3-Hour Test from Genova Diagnostics is a diagnostic tool designed to assess for Small Intestinal Bacterial Overgrowth (SIBO). SIBO is a condition where excessive bacteria are present in the small intestine. This can lead to various symptoms like bloating, gas, abdominal pain, diarrhea, and nutritional deficiencies. The SIBO 3-Hour Test is specifically designed to detect this condition by measuring the levels of hydrogen (H2) and methane (CH4) gases in the breath, which are byproducts of bacterial metabolism.

The test begins with the patient ingesting a lactulose solution. Lactulose is a type of sugar that is not absorbed in the gut but is fermented by intestinal bacteria. The fermentation process produces gases, including hydrogen and methane.

Over the course of three hours, the patient's breath is captured at regular intervals. This non-invasive method involves the patient breathing into a collection device. The captured breath samples are analyzed for hydrogen and methane levels.

  • Hydrogen: An increase in hydrogen levels can indicate the presence of hydrogen-producing bacteria in the small intestine, indicating the sugar was not digested well.
  • Methane: Elevated methane levels are often associated with constipation-predominant symptoms and can indicate the presence of methane-producing bacteria.

By analyzing the pattern and quantity of these gases over the three-hour period, healthcare providers can determine if the patient's symptoms are likely due to SIBO. Typically, an early rise in the levels of these gases, especially within the first two hours after ingestion of lactulose, suggests SIBO.

The test aims to evaluate Small intestinal bacterial overgrowth (SIBO).

Which Patients is the SIBO 3-Hour Best Used For?

Clinicians have the option of a 2-hour or 3-hour SIBO assessment.

The 3-hour SIBO profile is designed to offer a comprehensive view of gas levels over a prolonged duration. This extended testing period is particularly recommended for patients who experience slower gastrointestinal transit or suffer from constipation.

In the condition known as Small Intestinal Bacterial Overgrowth (SIBO), there is an abnormal escalation in the overall bacterial population within the small intestine. This increase typically involves bacteria that are not usually present in that segment of the digestive system.

SIBO is often observed in scenarios where surgical procedures or illnesses impede the normal movement of food and waste through the digestive tract, creating an environment that promotes the proliferation of certain bacteria.

Conditions Commonly Associated with SIBO Include:

Several conditions are commonly associated with Small Intestinal Bacterial Overgrowth (SIBO), each having its unique way of potentially contributing to or being affected by SIBO. Based on the provided list, these conditions include:

  1. Irritable Bowel Syndrome (IBS): IBS is one of the most frequently associated conditions with SIBO. Research suggests that a significant portion of IBS patients also have SIBO. The symptoms of SIBO, such as bloating, abdominal discomfort, and altered bowel habits, closely mirror those of IBS, making the relationship between these two conditions a focus of ongoing research.
  2. Inflammatory Bowel Disease (IBD): This group of disorders, including Crohn's disease and ulcerative colitis, involves chronic inflammation of the gastrointestinal tract. People with IBD may be more susceptible to developing SIBO due to intestinal inflammation, structural changes in the gut, and motility issues that can accompany these conditions.
  3. Celiac Disease: Celiac disease, an autoimmune disorder triggered by gluten ingestion, leads to damage in the small intestine. This damage can disrupt the normal absorption and motility processes in the gut, creating an environment conducive to bacterial overgrowth.
  4. Diabetes: Patients with diabetes, especially those with long-standing or poorly controlled disease, can develop diabetic neuropathy, which affects gut motility. This decreased motility can lead to stasis and subsequent overgrowth of bacteria in the small intestine.
  5. Fibromyalgia: While the link between fibromyalgia and SIBO is not fully understood, studies have shown that patients with fibromyalgia often have gastrointestinal symptoms similar to those of SIBO. The connection may be related to the overall hypersensitivity and pain perception disorders characteristic of fibromyalgia.
  6. Rosacea: An interesting association has been found between rosacea, a skin condition characterized by facial redness and flushing, and SIBO. Some studies suggest that treating SIBO can lead to improvement in rosacea symptoms, indicating a potential gut-skin axis.
  7. Parkinson's Disease: Patients with Parkinson's Disease often experience gastrointestinal motility issues, which can predispose them to developing SIBO. The relationship between the gut and neurological health, as seen in Parkinson's Disease, is an emerging area of research.
  8. Obesity: There is growing evidence linking the gut microbiome to obesity. Changes in the composition and function of the gut bacteria, as seen in SIBO, can influence metabolic processes and potentially contribute to the development or exacerbation of obesity.

Each of these conditions has its own mechanism by which it might be associated with or contribute to the development of SIBO, highlighting the complexity and multi-faceted nature of this gastrointestinal disorder. Understanding these associations is crucial for effective management and treatment of SIBO, especially in patients with these concurrent conditions.

Common Causes of SIBO

Common causes of Small Intestinal Bacterial Overgrowth (SIBO) encompass a range of factors that interfere with the normal functioning of the digestive system. Reduced stomach acid production is a significant contributor, where both naturally low stomach acid and the use of acid-reducing medications like Proton Pump Inhibitors (PPIs), antacids such as Tums and Pepcid, and others including Prilosec and immunosuppressants, can diminish the stomach's ability to control bacterial growth.

Impaired gut motility and structural issues also play a crucial role. Conditions like gastroparesis, which slows down the movement of food from the stomach to the small intestine, along with chronic constipation and slow digestion, create an environment conducive to bacterial overgrowth. Surgeries such as C-sections, endometriosis operations, hysterectomies, and tummy tucks can lead to scar tissue, potentially disrupting normal intestinal functions and leading to SIBO. Additionally, structural abnormalities like ileocecal valve disorders or the effects of bariatric surgery can alter the normal gut anatomy, affecting bacterial populations.

Underlying medical conditions are also key factors. Celiac disease, an autoimmune disorder that damages the small intestine lining, can affect its ability to function properly, potentially leading to SIBO. Similarly, hypothyroidism, characterized by low thyroid hormone levels, can slow down bodily processes, including gut motility, contributing to the development of SIBO.

Lifestyle and dietary factors significantly impact the risk of developing SIBO. Chronic stress, leading to high cortisol levels, can affect gut motility and the immune system, potentially leading to an imbalance in gut bacteria. Diets high in sugar, processed carbs, and alcohol disrupt the normal gut microbiome, encouraging the growth of bacteria that thrive on these substrates.

Lastly, gastrointestinal infections from bacteria like H. pylori, E. coli, and Klebsiella can disrupt the normal gut flora balance. Incidents of food poisoning, especially those causing IBS-D (Irritable Bowel Syndrome with Diarrhea) or SIBO-D (SIBO with Diarrhea), can also lead to conditions favorable for SIBO. Each of these factors can independently or in combination contribute to the development of SIBO by altering the gut's bacterial balance, motility, structural, and immune environments, making it crucial to identify and address these underlying causes when treating SIBO for effective and long-lasting results.

Symptoms of SIBO

The excess bacteria may cause gas, burping, bloating, diarrhea, weight loss, and malnutrition. Other symptoms are:

Symptoms of Small Intestinal Bacterial Overgrowth (SIBO) can vary widely among individuals, but there are several common symptoms that are often reported, including gas, burping, bloating, diarrhea, weight loss, and malnutrition. Other symptoms include:

  1. Bloating Worse at the End of the Day: One of the hallmark symptoms of SIBO is bloating that worsens as the day progresses. This is likely due to the accumulation of gases produced by the overgrowth of bacteria in the small intestine, which increases with the intake of food throughout the day.
  2. Improvement on a Low FODMAP Diet: Patients with SIBO often report feeling better when they follow a Low FODMAP diet. FODMAPs (Fermentable Oligo-, Di-, Mono-saccharides, And Polyols) are short-chain carbohydrates that are poorly absorbed in the small intestine and are fermented by bacteria, leading to gas production and digestive discomfort. A reduction in FODMAP intake can alleviate these symptoms by reducing the substrate available for fermentation by the overgrown bacteria.
  3. Relief of Symptoms Following Antibiotic Treatment: Many patients with SIBO experience a significant improvement in symptoms after undergoing antibiotic treatment. Antibiotics can reduce the overgrowth of bacteria in the small intestine, thereby diminishing the production of gases and other byproducts that contribute to symptoms like bloating and discomfort.
  4. Worsening of Symptoms After Taking Probiotics: Interestingly, some patients with SIBO feel worse after taking probiotics. This may occur because probiotics can add more bacteria to an already overpopulated small intestine, exacerbating symptoms like bloating and gas.
  5. Feeling of Fullness or Gas Immediately After Eating: Patients with SIBO often experience an immediate and uncomfortable feeling of fullness or gas after eating. This symptom is likely due to the rapid fermentation of food by the excess bacteria present in the small intestine, leading to the production of gas and resulting in discomfort and bloating soon after a meal.

These symptoms, while indicative of SIBO, can also overlap with other gastrointestinal disorders. Therefore, a proper medical evaluation, often including diagnostic tests like the SIBO breath test, is essential for accurate diagnosis and treatment.

What Does SIBO 3-hour Test Measure?

The SIBO-3-hour test measures hydrogen and methane levels on eight breaths collected in tubes after consuming a lactulose solution. The tubes are shipped to the lab.

Fasting for 12 hours before the test is required, and patients should not be taking probiotics 24 hours before the test.

What Type of Sample is Needed to Complete the SIBO 3- Hour test?

Eight fasting breath samples are required for the test. Patients will collect the samples following the collection instructions indicated by Genova Diagnostics.


*The test is not recommended for individuals who have allergic reactions to lactulose or are on a lactose-restricted diet.

*This test is not appropriate for children under 25 pounds

About the Test

The 3-hour SIBO assessment is a non-invasive test that evaluates bacterial overgrowth of the small intestine. This longer test is recommended for patients with slower gastrointestinal transit or constipation.

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Sample Type
Shipping Time
5 - 10 days
Turnaround Time
21 days
Test Preparation Starts
Up to 14 days before collection
Number of Collection Days
1 day
Methods Used For Processing
Lab Certifications
CLIA Certified
CAP Accredited
ISO 15189
COLA Accredited
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