Evaluation of gaxilose (LacTEST 0.45 g) as a marker of intestinal barrier integrity in patients with celiac disease

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What is this study about?

The study focuses on celiac disease, a condition in which eating gluten damages the lining of the small intestine and can lead to problems with nutrient absorption. Participants will follow a gluten‑free diet, which is the usual treatment for this condition, and will be given a small oral dose of LacTEST 0.45 g, a powder that contains a sugar called gaxilose. The aim is to see if the test can serve as a simple marker of the health of the intestinal lactase activity, the intestinal barrier, and the intestinal permeability, meaning how well the gut lining keeps unwanted substances out.

People with the condition will take the test powder by mouth and then provide urine samples a few hours later, while blood and stool samples will also be collected at scheduled visits. These visits will occur at the start of the study, after about six months, and again after twelve months, during which the usual diet advice will continue. The study will compare the test results with standard assessments such as the Marsh-Oberhuber classification that describes the degree of intestinal damage, to determine whether the test reliably reflects changes in the gut over time.

1 baseline assessment

on the day you join the study you will attend a baseline visit. during this visit you will provide a blood sample, a stool sample, and a urine sample that will be collected after taking the test dose. you will also answer several questionnaires that evaluate gastrointestinal symptoms, quality of life, and adherence to a gluten‑free diet. additional laboratory measurements such as antitransglutaminase antibodies and markers of intestinal permeability will be performed on the collected samples.

2 first lactest administration

you will receive a single dose of lactest 0.45 g powder intended for oral solution. dissolve the powder in the amount of water instructed by the study staff and drink it once. five hours after ingestion you will collect a urine sample, which will be used to measure the amount of xylose excreted. the urine sample is then returned to the study team according to the instructions provided.

3 six‑month follow‑up visit

approximately six months after the baseline visit you will attend a follow‑up visit. the same procedures as at baseline are repeated: a new dose of lactest 0.45 g is taken orally, a urine sample is collected five hours later, and new blood and stool samples are obtained. you will also complete the same set of questionnaires to assess symptoms and diet adherence. additional measurements such as the lactulose/mannitol test, lipopolysaccharide‑binding protein, soluble cd14, zonulin in stool, and inflammatory cytokines may be performed on the collected samples.

4 twelve‑month final visit

twelve months after the start of the study you will attend the final visit. you will repeat the oral dose of lactest 0.45 g, collect a urine sample five hours after ingestion, and provide blood and stool samples for the same laboratory analyses performed at earlier visits. the final set of questionnaires will be completed to evaluate any changes in symptoms, quality of life, and diet adherence. results from the baseline, six‑month, and twelve‑month assessments will be compared to determine changes in intestinal lactase activity, intestinal barrier integrity, and related biomarkers.

Who Can Join the Study?

Be an adult between 18 and 70 years old who is thought to have celiac disease because they have symptoms that match the condition and a blood test that shows positive anti‑TG antibodies (proteins the immune system makes against a tissue‑transglutaminase enzyme) and they have one of the genetic markers called HLA DQ2 or HLA DQ8 (specific DNA patterns that increase the risk for celiac disease).
Be able to understand what the study involves and be willing to sign an informed consent form (a document that explains the study and confirms the participant agrees to take part).

Who Cannot Join the Study?

Pregnancy or breastfeeding – you cannot join the study if you are currently pregnant or feeding a baby.
Myxedema – a severe condition caused by very low thyroid hormone levels that leads to swelling of the skin and other tissues.
Pentosuria or galactosemia – rare inherited disorders where the body cannot properly process certain sugars.
Allergy to Gaxilose – if you are known to have a hypersensitivity (allergic reaction) to the active ingredient Gaxilose, you cannot participate.
Use of blood‑thinning medicines (anticoagulants or antiplatelet drugs) that cannot be stopped before the scheduled endoscopy (a procedure that uses a camera to look inside the gut).
Any medical reason that makes an endoscopy with multiple biopsies unsafe, including if you are on blood‑thinners that cannot be paused 3‑5 days before the tissue samples are taken.
History of cancer (neoplasia) or active intestinal diseases that cause inflammation, bleeding, immune attacks on the gut, or infection, as well as any other untreated chronic illness that could cause diarrhea or poor nutrient absorption.
Severe and long‑lasting mental health conditions, such as psychosis (loss of touch with reality).
Diagnosed with Parkinson’s disease, dementia, or other neurodegenerative diseases (disorders where brain cells progressively deteriorate).
Having liver cirrhosis (serious scarring of the liver) or other chronic liver or digestive diseases, or having had major digestive surgery (except simple surgeries like removal of the appendix or gallbladder).
Moderate or severe kidney failure – when the kidneys are not functioning well enough.

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Htfipjwy Vvrs doigleja	Barcelona	Spain

Trial status

Country	Status	Recruitment Start
Spain	Not yet recruiting	04.05.2026

Trial locations

Investigated drugs:

GAXILOSE

LacTEST is a diagnostic product that comes as a powder to be mixed with water and taken by mouth. It contains a substance called gaxilose, which is specially designed to be broken down by the enzyme lactase in the small intestine. By measuring how well gaxilose is processed, doctors can see how active the lactase enzyme is, which helps them understand the health of the intestinal lining. In this study, LacTEST is used to check if the activity of lactase reflects the condition of the intestinal wall and its ability to act as a barrier, especially in people with celiac disease. This information may help doctors monitor disease activity and recovery without needing more invasive procedures.

Investigated diseases:

Coeliac disease

Celiac disease – Celiac disease is an immune‑mediated condition where the small intestine reacts to gluten, a protein found in wheat, barley, and rye. When gluten is eaten, the immune response damages the lining of the intestinal wall, flattening the tiny finger‑like projections called villi. This damage reduces the intestine’s ability to absorb nutrients. Over time, the injury can become more severe if gluten exposure continues, leading to a wider area of the gut being affected. The condition may appear at any age and can vary from mild to more extensive intestinal changes.

Trial ID:

2026-525518-70-00

Protocol code:

VPH-GXL-2025-04

Trial Phase:

Therapeutic confirmatory (Phase III)

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Evaluation of gaxilose (LacTEST 0.45 g) as a marker of intestinal barrier integrity in patients with celiac disease

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?