{
  "abstract": "Introduction Lactulose–mannitol (L:M) urinary recovery is an established marker of intestinal permeability, but conventional 5–8 hour urine collections are burdensome. Shortened protocols may improve practicality. Emerging evidence suggests that permeability disturbances in disorders of gut–brain interaction arise predominantly in the small intestine, making reducedduration testing potentially more relevant. This study aimed to generate preliminary reference values for a 3 hour L:M protocol in healthy adults.Methods Thirty-seven healthy adults aged ≥18 years were recruited to the study ( NCT07145658). Participants had no significant medical conditions, prescription medication use, gastrointestinal symptoms, recent infection, NSAID use within 28 days, or recent intense exercise. To reduce background dietary mannitol, individuals followed a controlled diet the preceding day and fasted for 12 hours. On arrival, participants consumed 500 ml water and provided a fasted void before ingesting a dualsugar probe (lactulose 10 g, mannitol 2.5 g). Cumulative urine was collected over 3 hours, supported by a standardised 1000 ml water intake during the first 2 hours to promote adequate urine output.Total urine volume was recorded, and an aliquot underwent multistep preparation to remove impurities. Sugar concentrations were quantified using Agilent 1100 series highperformance liquid chromatography (HPLC) with a resinbased cationexchange column and refractive index detection. Percentilebased reference limits were derived.. Breath hydrogen sampling was performed at 10 time points (0–180 minutes) to assess fermentation onset and confirm smallbowel availability of the sugars during the 3hour collection window.Results Thirtyfive participants were included in the analysis (mean age 29 years [range18-37]; 66% female). Two participant values falling below the analytical detection limit were excluded. The L:M ratio showed right skewing, with logtransformed values approaching normality. Median (IQR) L:M ratio was 0.00570 (0.00307–0.00932). Proposed upper reference limits were 0.043 (90th percentile) and 0.0595 (95th percentile). Breath hydrogen increased by ≥20 ppm in all participants, with a median rise of 130 ppm (IQR 100–184) and a median timetopeak of 120 minutes (IQR 120–150), supporting timely transit beyond the stomach and availability of the sugar probe to fermenting microbiota within the 3hour collection period.Conclusions This study establishes initial reference values for a reduced 3hour L:M permeability test in healthy adults. The accompanying breathhydrogen data support the physiological validity of the shortened protocol. These findings provide a foundation for further validation in healthy and symptomatic populations.",
  "authors": [
    {
      "affiliations": [
        "The Functional Gut Clinic, Manchester, United Kingdom"
      ],
      "name": "Sam Treadway"
    },
    {
      "affiliations": [
        "The Functional Gut Clinic, Manchester, United Kingdom"
      ],
      "name": "Sowmya Chinta"
    },
    {
      "affiliations": [
        "The Functional Gut Clinic, Manchester, United Kingdom"
      ],
      "name": "Jordan Haworth"
    },
    {
      "affiliations": [
        "The Functional Gut Clinic, Manchester, United Kingdom"
      ],
      "name": "Anthony Hobson"
    }
  ],
  "title": "P395 Measurement of intestinal permeability: preliminary reference values for a reduced 3 hour lactulose–mannitol test in healthy adults",
  "uid": "5e5cb3d7-642b-5481-90fb-37ead46c9729"
}