Gut tests: which ones are worth it?

Whether celiac disease is likely. Total IgA is checked because low IgA can cause a false negative.

Non-celiac gluten sensitivity. The test is unreliable if you've already cut out gluten.

Whether there's inflammation in the bowel, helping separate inflammatory bowel disease from IBS-type symptoms.

IBS or endometriosis. Anti-inflammatory painkillers (NSAIDs), commonly used for endometriosis pain, can raise it.

Anemia (a red flag, or a sign of celiac disease or heavy periods) and general inflammation.

The cause of gut symptoms. Guidelines disagree about how useful CRP is here.

A common, treatable parasite in ongoing diarrhea.

Much in a general parasite screen without travel or exposure risk — the American Gastroenterological Association advises against routine ova and parasite testing without that risk.

A treatable cause of upper-belly pain or fullness.

Anything about lower-bowel or IBS symptoms. Some medicines (acid reducers, antibiotics) need to be paused beforehand — ask your clinician.

A treatable cause of chronic watery diarrhea, especially after gallbladder removal or with nighttime diarrhea.

Much in typical IBS.

Lactose malabsorption.

Much that a simple diet trial wouldn't — UK guidelines see no role for breath tests in typical IBS.

A possible sign of bacterial or methane-producing overgrowth.

A reliable diagnosis. Accuracy varies widely compared with direct sampling, and the lactulose version is known for false positives. The US guideline's suggestion to test is based on very low-quality evidence; UK guidelines advise against it in IBS.

Gastroparesis, when more than 10% of a test meal remains after 4 hours.

Much in typical indigestion — most people with those symptoms have normal emptying. Some medications, including opioids and GLP-1 drugs, affect results.

Pelvic floor dyssynergia — when the muscles don't coordinate to empty the bowel. It's treatable with biofeedback.

Endometriosis or hEDS — but it's worth asking about if you have either and struggle with straining or incomplete emptying.

A research-style description of gut bacteria.

Anything shown to improve care. A 2025 international consensus found insufficient evidence for routine use and said reports shouldn't include treatment advice.

Which foods you eat — IgG reflects exposure.

Intolerance or allergy. Allergy societies and the British Society of Gastroenterology advise against IgG-based diets.

Nothing reliable — a widely used commercial kit was shown not to detect the protein identified as zonulin.

Intestinal permeability in research studies.

Anything with an agreed clinical cutoff or treatment plan.

No published evidence validates them for diagnosing gut problems. "Candida overgrowth" isn't an established diagnosis.