Urinary mannitol: lactulose excretion ratios and jejunal mucosal structure

Area of Science:

• Pediatric Gastroenterology
• Gastrointestinal Physiology
• Diagnostic Testing

Background:

• Assessing small intestinal mucosal integrity is crucial for diagnosing pediatric enteropathies.
• Non-invasive diagnostic methods are desirable for pediatric gastrointestinal evaluations.
• Dual sugar absorption tests offer a potential non-invasive approach to assess intestinal permeability.

Purpose of the Study:

• To evaluate the diagnostic accuracy of a dual sugar (mannitol, lactulose) absorption test in children with varying degrees of mucosal damage.
• To establish reference ranges and assess the test's correlation with body surface area.
• To determine the test's utility in monitoring mucosal changes in response to therapeutic interventions like gluten withdrawal.

Main Methods:

• A dual sugar absorption test using mannitol and lactulose was administered orally to a study group of 43 children with mucosal damage and 53 healthy controls.
• Urinary excretion ratios of mannitol and lactulose were measured over three hours post-administration.
• Correlation with body surface area was analyzed, and a lower limit of normal was established.
• Sensitivity and specificity for severe villous atrophy were calculated. Sequential studies were conducted in 18 children.

Main Results:

• A significant positive correlation was observed between the urinary mannitol: lactulose ratio and body surface area in controls.
• The test demonstrated high specificity (98%) and sensitivity (95%) for severe villous atrophy.
• Sensitivity decreased significantly with milder degrees of mucosal damage, indicating it's not ideal for screening all enteropathies.
• Sequential studies showed the ratio changes reflected mucosal structural alterations induced by gluten challenges or withdrawal.

Conclusions:

• The dual sugar absorption test is highly accurate for diagnosing severe villous atrophy in children.
• The test's utility is limited as a general screening tool for all enteropathies due to declining sensitivity with less severe mucosal damage.
• This absorption test shows promise for sequential monitoring of small intestinal mucosal lesions, particularly in response to dietary interventions.