Development of a Noninvasive Metric to Measure Small Bowel Sensation - The Small Intestine Stress Test

The purpose of this research is to identify the concentration of mannitol solution (a type of sugar alcohol) that will generate a range of symptoms in individuals without Disorders of Gut Brain Interaction (DGBI) to establish the normative range of responses to small bowel (SB) distension.

Study Overview

• Status: Recruiting
• Conditions: Disorders of Gut Brain Interaction
• Intervention / Treatment: Drug: Mannitol Solution 76 mOsm/L; Drug: Mannitol Solution 189 mOsm/L; Drug: Mannitol Solution 325 mOsm/L; Diagnostic test: Scintigraphy

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Taylor Hines; Phone Number: 507-538-9959; Email: hines.taylor@mayo.edu

Study Locations

• United States
  • Minnesota
    • Rochester, Minnesota, United States, 55905
      • Recruiting
      • Mayo Clinic
      • Contact: Taylor Hines; Phone Number: 507-538-9959

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• No current gastrointestinal symptoms
• No prior history of GI disorders, in particular DGBIs
• Ability to provide informed consent
• Ability to participate in study procedures
• Absence of other diseases (structural or metabolic) which could interfere with interpretation of the study results
• For females, must not be pregnant or lactating due to radiation exposure.
• Stable doses of thyroid replacement, estrogen replacement, low-dose aspirin for cardioprotection, and birth control are permissible.

Exclusion Criteria

• Subjects on any medications that impact transit or integrity of small bowel mucosal barrier (e.g. chronic NSAIDS) of the GI tract will be excluded.
• Patients with prior bowel surgery (not including appendectomy and cholecystectomy)
• Patients who may have altered sensation (central sensitization or conditions that may induce bowel hyperalgesia) based on PI review of medical history (ie, fibromyalgia, endometriosis, chronic pelvic pain)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Healthy Volunteers Receiving Mannitol Solutions; Healthy adult volunteers will receive all three mannitol solution osmolarities-76 milliosmol (mOsm/L), 189 mOsm/L, and 325 mOsm/L-on three separate testing occasions spaced at least 5 days apart. Each solution will be administered orally as 500 mL radiolabeled with Pentetate Indium Disodium In-111 (111Indium-DTPA).

Drug: Mannitol Solution 76 mOsm/L; Participants will ingest 500 mL of mannitol solution at 76 mOsm/L radiolabeled with 111Indium-DTPA during one testing visit.; Drug: Mannitol Solution 189 mOsm/L; Participants will ingest 500 mL of mannitol solution at 189 mOsm/L radiolabeled with 111Indium-DTPA during one testing visit.; Drug: Mannitol Solution 325 mOsm/L; Participants will ingest 500 mL of mannitol solution at 325 mOsm/L radiolabeled with 111Indium-DTPA during one testing visit.; Diagnostic test: Scintigraphy; Scintigraphy will be used to track gastric emptying, small bowel transit, and colonic filling of the radiolabeled mannitol solution during each testing visit.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak Gastrointestinal Symptom Severity During Small Bowel Transit Following 76 mOsm/L Mannitol Solution Ingestion	Peak gastrointestinal symptom severity will be assessed using a 7-point Likert symptom scale after ingestion of radiolabeled mannitol solution. Symptoms assessed include abdominal pain or discomfort, nausea, bloating, distension, borborygmi, diarrhea, urgency, and related gastrointestinal symptoms. The peak symptom score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Scores range from 1 to 7, with higher scores indicating greater symptom severity.	At baseline and at 15-minute intervals beginning 30 minutes after ingestion through 180 minutes post-ingestion.
Peak Gastrointestinal Symptom Severity During Small Bowel Transit Following 189 mOsm/L Mannitol Solution Ingestion	Peak gastrointestinal symptom severity will be assessed using a 7-point Likert symptom scale after ingestion of radiolabeled mannitol solution. Symptoms assessed include abdominal pain or discomfort, nausea, bloating, distension, borborygmi, diarrhea, urgency, and related gastrointestinal symptoms. The peak symptom score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Scores range from 1 to 7, with higher scores indicating greater symptom severity.	At baseline and at 15-minute intervals beginning 30 minutes after ingestion through 180 minutes post-ingestion.
Peak Gastrointestinal Symptom Severity During Small Bowel Transit Following 325 mOsm/L Mannitol Solution Ingestion	Peak gastrointestinal symptom severity will be assessed using a 7-point Likert symptom scale after ingestion of radiolabeled mannitol solution. Symptoms assessed include abdominal pain or discomfort, nausea, bloating, distension, borborygmi, diarrhea, urgency, and related gastrointestinal symptoms. The peak symptom score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Scores range from 1 to 7, with higher scores indicating greater symptom severity.	At baseline and at 15-minute intervals beginning 30 minutes after ingestion through 180 minutes post-ingestion.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak Abdominal Pain Intensity Following 76 mOsm/L Mannitol Solution	Peak abdominal pain intensity will be assessed after ingestion of 500 mL radiolabeled 76 mOsm/L mannitol solution using the Kohn Reactivity Scale. The peak pain intensity score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Higher scores indicate greater pain intensity.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion
Peak Abdominal Pain Intensity Following 189 mOsm/L Mannitol Solution	Peak abdominal pain intensity will be assessed after ingestion of 500 mL radiolabeled 189 mOsm/L mannitol solution using the Kohn Reactivity Scale. The peak pain intensity score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Higher scores indicate greater pain intensity.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion
Peak Abdominal Pain Intensity Following 325 mOsm/L Mannitol Solution	Peak abdominal pain intensity will be assessed after ingestion of 500 mL radiolabeled 325 mOsm/L mannitol solution using the Kohn Reactivity Scale. The peak pain intensity score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Higher scores indicate greater pain intensity.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion
Peak Abdominal Pain Unpleasantness Following 76 mOsm/L Mannitol Solution	Peak abdominal pain unpleasantness will be assessed after ingestion of 500 mL radiolabeled 76 mOsm/L mannitol solution using the Kohn Reactivity Scale. The peak pain unpleasantness score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Higher scores indicate greater pain unpleasantness.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion
Peak Abdominal Pain Unpleasantness Following 189 mOsm/L Mannitol Solution	Peak abdominal pain unpleasantness will be assessed after ingestion of 500 mL radiolabeled 189 mOsm/L mannitol solution using the Kohn Reactivity Scale. The peak pain unpleasantness score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Higher scores indicate greater pain unpleasantness.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion
Peak Abdominal Pain Unpleasantness Following 325 mOsm/L Mannitol Solution	Peak abdominal pain unpleasantness will be assessed after ingestion of 500 mL radiolabeled 325 mOsm/L mannitol solution using the Kohn Reactivity Scale. The peak pain unpleasantness score observed during the small bowel phase will be identified. The small bowel phase is defined as the period during which scintigraphy confirms radiolabeled solution in the small bowel and before more than 25% of tracer has reached the ascending colon. Higher scores indicate greater pain unpleasantness.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion
Change in Gastrointestinal Symptom Severity Following 76 mOsm/L Mannitol Solution	Gastrointestinal symptom severity will be assessed after ingestion of 500 mL radiolabeled 76 mOsm/L mannitol solution using a modified Gastric Symptom Severity Scale. Symptoms assessed include abdominal pain or discomfort, nausea, bloating, distension, borborygmi, diarrhea, loose stools, urgency, and related gastrointestinal symptoms. Scores range from 1 to 7, with higher scores indicating greater symptom severity.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion
Change in Gastrointestinal Symptom Severity Following 189 mOsm/L Mannitol Solution	Gastrointestinal symptom severity will be assessed after ingestion of 500 mL radiolabeled 189 mOsm/L mannitol solution using a modified Gastric Symptom Severity Scale. Symptoms assessed include abdominal pain or discomfort, nausea, bloating, distension, borborygmi, diarrhea, loose stools, urgency, and related gastrointestinal symptoms. Scores range from 1 to 7, with higher scores indicating greater symptom severity.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion
Change in Gastrointestinal Symptom Severity Following 325 mOsm/L Mannitol Solution	Gastrointestinal symptom severity will be assessed after ingestion of 500 mL radiolabeled 325 mOsm/L mannitol solution using a modified Gastric Symptom Severity Scale. Symptoms assessed include abdominal pain or discomfort, nausea, bloating, distension, borborygmi, diarrhea, loose stools, urgency, and related gastrointestinal symptoms. Scores range from 1 to 7, with higher scores indicating greater symptom severity.	Baseline, then every 15 minutes from 30 minutes through 180 minutes after ingestion

Collaborators and Investigators

• Sponsor: Mayo Clinic
• Investigators: Principal Investigator: Xiao Jing Wang, MD, Mayo Clinic

Study record dates

Study Major Dates

• Study Start (Estimated): August 24, 2026
• Primary Completion (Estimated): June 30, 2027
• Study Completion (Estimated): December 30, 2027

Study Registration Dates

• First Submitted: September 8, 2026
• First Submitted That Met QC Criteria: September 8, 2026
• First Posted (Actual): September 14, 2026

Study Record Updates

• Last Update Posted (Actual): September 14, 2026
• Last Update Submitted That Met QC Criteria: September 8, 2026
• Last Verified: September 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Diagnostic Techniques and Procedures; Diagnosis; Diagnostic Imaging; Diagnostic Techniques, Radioisotope; Radionuclide Imaging
• Other Study ID Numbers: 25-013906

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No