Start here.
This is currently the best test for SIBO. It measures methane and hydrogen levels over the course of three hours.
Lactulose breath tests are available from many doctors and laboratories.
Important things to know:
Example test output:
Utility of SIBO lactulose breath test for methane and hydrogen:
Save this for after a positive breath test.
Not as valuable for constipation-predominant SIBO.
This test looks for food-poisoning-related antibodies in the blood. If these antibodies are present, you know the root cause of your SIBO is semi-permanent intestinal nerve damage from food poisoning, and you can treat the underlying cause appropriately with prokinetics, meal spacing, and (to a lesser extent) nerve healers.
The higher the anti-vinculin value, the more likely your case will be chronic and difficult to treat (anti-vinculin > 3.0 starts to be really challenging to treat). Similarly, a positive test result means you'll want to be extra careful not to get food poisoning again at the risk of worsening your SIBO symptoms and outlook.
Knowing the underlying cause of a condition like SIBO is helpful not only for guiding treatment but is often also a relief to those that have been grasping at straws for a long time trying to understand what is wrong with them.
There are many, many underlying or predisposing conditions that can cause SIBO. As mentioned elsewhere, food poisoning appears to be the most common and can be tested with the IBS Blood Test described above. That would be a good place to start after a positive breath test for diarrhea or mixed-type SIBO patients.
Other tests to possibly look at include small intestine motility studies and a barium swallow to look for obstructions, adhesions, and any other structural issues in the small intestines. For motility testing, you're generally trying to see if the migrating motor complex in the small intestine is functioning properly. "Smart pills" at places like the University of Louisville can measure this remotely. Otherwise the main test is a procedure called antroduodenal manometry.
Another easy one to check off the list would be Ehlers-Danlos syndrome. More underlying causes to consider are hypothyroid, diabetes, autoimmune issues, and the list goes on and on. SIBO is almost always a consequence of something else.
This list is not exhaustive, but don't be discouraged -- treatment of the underlying cause is often the same. A majority of SIBO ultimately occurs because of poor gastrointestinal motility, and there is a class of drugs called prokinetics that are specifically designed to treat gut motility issues. We'll dive into prokinetics more in the treatment section.
In case you aren't 100% sure and don't want to dive right into expensive testing and doctor appointments.
Because SIBO symptoms overlap with many other diseases (such as IBD), it is not possible to diagnose SIBO by symptoms alone. However, given the prevalence of SIBO, we can strengthen our hypothesis with a few clues:
Common symptoms:
Made worse by:
Made better by:
History: