How SIBO is Diagnosed

In our recent post, we gave an overview of Small Intestinal Bacterial Overgrowth—otherwise known as SIBO. It can be an insidious disease, because so many of its symptoms overlap with other gut ailments. Misdiagnosis, or missing a diagnosis all together, is very common. Yet the longer SIBO goes untreated, the more difficult it can be to resolve. Furthermore, its treatment is specific and must be handled in the right way in order to achieve full recovery. That makes an accurate diagnosis all the more imperative. This post will cover the various kinds of SIBO as well as the tests used to reveal them. 

SIBO Variations

It’s important to note that there are three types of SIBO. This is because multiple bacteria—as well as microorganisms—contribute to overgrowth in the small intestine, and the way they combine can produce a buildup of three different gases in your gut: methane, hydrogen or or sulfide. While there are foundational aspects to treating SIBO as a whole, it’s essential to determine the type of SIBO you have as it could determine the treatment you receive.

Hydrogen-Dominant SIBO

Hydrogen-dominant SIBO occurs when food lingers in your small intestine for too long and begins to ferment before it can be broken down. This creates excess hydrogen gas in your gut and can cause symptoms unique to this kind of SIBO: diarrhea and flatulence that smells like rotten eggs. 

Methane-Dominant SIBO

Methane-dominant SIBO occurs when the normal digestion process is slowed up and excess methane—essential in the normal levels for regulating hydrogen and carbon dioxide in the gut—accumulates and causes abdominal pain, bloating and constipation. Additionally this excess methane produced by archaea in the small intestine slows down the intestinal motility and transit time of food through the gastrointestinal tract. Oftentimes these people feel inadequate evacuation of the bowels, straining or will go 

Hydrogen Sulfide-Dominant SIBO

Hydrogen sulfide-dominant SIBO is when their is an overproduction of hydrogen sulfide. It a balanced body, hydrogen sulfide is a beneficial gasotransmitter which is a gaseous molecule that acts as a neurotransmitter. In balanced levels, hydrogen sulfide is a protective, anti-inflammatory agent with antioxidant and immune-supporting properties. If hydrogen sulfide levels proliferate it can cause damage to the gut, immune system, and cells along with initiating systemic inflammation. 

Small Intestinal Fungal Overgrowth

Known as SIFO, small intestinal fungal overgrowth is when high levels of fungi are found in the small intestine and contributes to various symptoms, similar to SIBO. Oftentimes those with unexplained gastrointestinal symptoms who test negative for SIBO actually have SIFO. 

Diagnosing SIBO

Currently, the most commonly used and least invasive way to test for SIBO is a breath test. 

Preparation for the test can begin anywhere from  2 to 4 weeks beforehand if you are on certain medications. Usually about 48 hours before the test a strict diet and elimination of non-essential medications is required to reduce baseline gases n your small intestine and therefore produce a more accurate result. Restrictions on smoking, alcohol and exercise are also recommended just prior to the test. 

During the testing process, patients will consume a sugar solution—such as glucose or lactulose—and then, at various intervals over a several hour span, blow into a special vial. If bacteria are fermenting in your small intestine—that is to say, the sugar is not being properly metabolized by your system— elevated levels of hydrogen, methane, of hydrogen sulfide will be detected, indicating the likelihood of SIBO. In the past, hydrogen sulfide gas was not able to be found with breath testing. Thankfully, reliable breath testing for hydrogen sulfide dominant SIBO is now available.

Although this method of breath testing is widely available and relatively easy, false negative and positive results are common. If results are unexpected and/or symptoms persist, it may be recommended that further or repeat testing. Small bowel aspiration procedures can be done, but these are incredibly invasive and usually utilized for research purposes. 

At-home breath test kits are available through many functional and integrative medicine doctors. It is highly recommend to not only test for SIBO, but also work to resolve SIBO, with the supervision of your physician. 

Next Up

In the third part of our SIBO series, we will discuss treatment options as well as dietary and lifestyle changes you can make today to avoid developing SIBO in the future. 

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