Introduction: In children with coeliac disease intestinal NO production is dependent on gluten intake. NO is oxidized to nitrite and nitrate (NOx) wich is excreted in the urine. The urinary NOx/creatinine-ratio can be used as an indicator for endogenous NO production.

Aims: To evaluate whether the increased urinary NOx/creatinine-ratio is specific for active coeliac disease.

Patients: The following patient groups were evaluated: active coeliac disease (n=27), coeliac disease on a gluten free diet for at least one year (n=10), acute bacterial gastoenteritis (n=8), acute viral gastroenteritis(n=6), acute undetermined gastroenteritis (n=7), inflammatory bowel disase(n=8), cystic fibrosis (n=14), bacterial airway infection (n=7), viral airway infection (n=5), meningococcal septic shock (n=5), healthy controls (n=11).

Methods: The Griess reagent method was used for the measurement of urinary NOx. The NOx/creatinine-ratio was expressed in mmol/mmol.

Results: Mean (SEM) urinary NOx/creatinine-ratios were: 1.85(0.27) in active coeliac disease, 0.30(0.06) in coeliac disease on a gluten free diet for at least one year, 0.83(0.24) in acute bacterial gastroenteritis, 0.72(0.11) in acute viral gastroenteritis, 0.33(0.09) in acute undetermined gastroenteritis, 0.27(0.05) in inflammatory bowel disease, 0.33(0.06) in cystic fibrosis, 0.11(0.02) in bacterial airway infection, 0.25(0.06) in viral airway infection, 0.16(0.04) in meningococcal septic shock and 0.11(0.02) in healthy controls.

Conclusion: Mean urinary NOx/creatinine ratios in active coeliac disease is significantly higher than in all control groups tested. Slight but significantly higher mean NOx/creatinine ratios were found in all control groups with gastrointestinal tract involvement.