• Posted January 13, 2026

Blood Test Can Predict Crohn's Disease, Researchers Say

A simple blood test can predict a person’s future risk for the GI illness Crohn’s disease, a new study says.

The test can predict Crohn’s years before symptoms appear, making possible early diagnosis, treatment and even prevention, researchers reported Jan. 12 in the journal Clinical Gastroenterology and Hepatology.

The test measures a person’s immune response to flagellin, a protein found on gut bacteria, researchers said. This response is elevated in people long before they develop Crohn’s disease.

“We wanted to know: do people who are at risk, who are healthy now, have these antibodies against flagellin?” said lead researcher Dr. Kenneth Croitoru, a clinical scientist with Mount Sinai’s Lunenfeld-Tanenbaum Research Institute in Toronto, Canada. 

“We looked, we measured, and yes indeed, at least some of them did,” Croitoru said in a news release.

Crohn’s disease causes chronic inflammation of the GI tract, according to the Crohn’s and Colitis Foundation. Symptoms include persistent diarrhea, rectal bleeding, abdominal cramps and constipation.

For the new study, researchers compared 77 relatives of people with Crohn’s who went on to develop the disease themselves against 304 who did not.

Among the folks who developed Crohn’s, more than a third (28) exhibited an elevated flagellin antibody response, results showed. The responses were strongest in siblings.

This pre-disease response to flagellin was also associated with intestinal inflammation and problems with a person’s gut function, both of which are characteristics of Crohn’s disease, researchers said.

Typically, a person developed Crohn’s nearly two and a half years after blood samples showed elevated flagellin antibodies, the study found.

These results suggests that a specific immune reaction involving flagellin might help trigger Crohn’s, Croitoru said.

That gives researchers a new target to investigate in the search to treat and prevent Crohn’s.

“With all of the advanced biologic therapy we have today, patients’ responses are partial at best,” Croitoru said. “We haven’t cured anybody yet, and we need to do better.”

More information

The Crohn’s and Colitis Foundation has more on Crohn’s disease.

SOURCE: Lunenfeld-Tanenbaum Research Institute, news release, Jan. 12, 2026