5 Tests That Can Reveal the Underlying Cause of Your Irritable Bowel Syndrome

Irritable Bowel Syndrome (IBS) affects an estimated 10–15% of adults worldwide, and yet most doctors aren't doing a great job of evaluating what's actually causing these symptoms. As a result, many people spend years struggling with bloating, constipation, diarrhea, and digestive distress without ever getting real answers.

Here's the deal: your conventional medicine doctor wasn't trained to look for many of the underlying causes of IBS.

If you missed Part 1 of this series, 5 Things You Haven't Tried for Irritable Bowel Syndrome (IBS) That Your Doctor May Never Have Mentioned, go check it out first!

Here are five tests I commonly use in my practice that help uncover the root cause of IBS and allow us to build treatment plans that actually get patients results.

1. GI MAP
   The GI-MAP is a functional stool test that takes a deep dive into your intestinal health. With this test, we can assess your microbiome, look for H. pylori, parasites, dysbiosis, and other bacterial and viral infections.

   But here's what I really love about this test is the intestinal health marker section.

   Here we're able to get insights into your gallbladder function, immune system (yes, you read that right), inflammation, intestinal permeability ("leaky gut"), and your ability to properly digest your food.

   WILD, right?

   Most doctors stop at, "Your colonoscopy is normal," and send you home with a medication to either help you poop...or stop the constant pooping.
   

2. 3-HOUR SIBO BREATH TEST

   Studies suggest that up to 85% of individuals diagnosed with IBS may actually have underlying Small Intestinal Bacterial Overgrowth (SIBO).

   This breath test evaluates whether bacteria have made their way into your small intestine.

   All your gut bacteria belong in your large intestine. When bacteria migrate into the small intestine, they begin fermenting the food you eat much earlier than they should, producing hydrogen and/or methane gas.

   That's where a lot of painful bloating, abdominal discomfort, constipation, diarrhea, and excessive gas come from.
   

3. IBS SMART TEST

   The IBS-Smart Test pairs beautifully with the 3-hour SIBO breath test.

   It's a simple at-home blood test that measures two evidence-based biomarkers: Anti-CdtB and Anti-vinculin antibodies. These markers are associated with post-infectious IBS and post-infectious SIBO.

   In plain English...

   A positive test suggests your digestive symptoms began after food poisoning, a stomach bug, or another gastrointestinal infection.

   I can't tell you how many patients tell me,

   "I had a stomach bug and my digestion has never been the same."

   If that's your story...

   Congratulations.

   You may have post-infectious SIBO.
   

4. CELIAC PANEL

   If I had a dollar for every time a patient told me,

   "I've already been tested for celiac."

   ...and they only had one marker checked...

   I'd be rich.

   Or they tell me,

   "I had an endoscopy and the biopsy was negative."

   While biopsies absolutely have their place, they aren't always the slam dunk people think they are.

   A complete celiac evaluation should include six blood markers:
   Tissue Transglutaminase IgA (tTG-IgA)
   Tissue Transglutaminase IgG (tTG-IgG)
   Deamidated Gliadin Peptide IgA (DGP-IgA)
   Deamidated Gliadin Peptide IgG (DGP-IgG)
   Endomysial Antibody IgA (EMA-IgA)
   Total Serum IgA.

   So why isn't a biopsy always definitive?

   Imagine trying to decide whether a chocolate chip cookie has chocolate chips by taking one tiny bite. If your bite doesn't happen to contain a chocolate chip, that doesn't mean the cookie doesn't have chocolate chips.

   The same concept applies here.

   Celiac disease can be patchy. If the biopsy samples an unaffected area instead of an affected one, the result can come back negative even when celiac disease is present.

   This actually happened to my boyfriend with appendix cancer. His appendix had ruptured, and the biopsy initially came back showing an abscess and infection. It was actually cancer.

   WILD.

   Most people have no idea that sampling matters.

   One important note: if you're being tested for celiac disease, you must still be eating gluten. Going gluten-free before testing can cause both blood work and biopsies to appear normal even if celiac disease is present.
   

5. H PYLORI

   While H. pylori is included on the GI-MAP, I think it deserves its own section because it is incredibly common and incredibly underdiagnosed.

   One reason?

   The testing commonly used in conventional medicine can miss infections.

   The urea breath test doesn't detect the bacteria itself—it detects urease activity, a byproduct produced by H. pylori.

   The GI-MAP uses quantitative PCR (qPCR) technology, which is generally more sensitive than traditional PCR methods and may detect lower levels of bacterial DNA.

   In plain English...

   It's often better at finding infections when only small amounts of bacteria are present.

All of these tests are the reason “your colonoscopy was normal” isn’t the mic drop your doctor thinks it is. And unfortunately, that’s where most of them stop. And not because they don’t care, but because their training didn’t teach them about any of the testing in this article.

If you’re looking for a fully comprehensive approach to uncover the root cause of your IBS + digestive distress that’s what we’re here for. Book a consult today + learn what your healing journey can look like!

Be sure to check out the rest of the series:

Part 1: 5 Things You Haven't Tried for Irritable Bowel Syndrome (IBS) That Your Doctor May Never Have Mentioned

Part 3: The IBS Treatments That Actually Work (And the Ones That Usually Don't)

Part 4:How to Finally Heal Your IBS: Putting All the Pieces Together