The purpose of this study is to establish reliable reference intervals for fecal S100A12 in healthy children.

RATIONALE S100A12 (calgranulin C) is a cytoplasmic protein secreted exclusively by activated neutrophils. It can be measured in stools and elevated levels are observed in children with inflammatory bowel disease. The protein is stable in stool samples for up to seven days at room temperature, which allows collection at home and potential delays in transport to the laboratory. S100A12 could be used as a marker to discriminate between pediatric inflammatory and functional gastro-intestinal conditions, and prevent children with a low probability of inflammation from unnecessary endoscopic procedures. Until now a reliable reference interval for healthy children is lacking.

OBJECTIVE To establish reliable reference intervals for fecal S100A12 in healthy children.

TIME FRAME Healthy children will be asked to send in one feces sample anonymously during the inclusion period. The investigators expect that the required 120 samples will be collected before December 2015. There will be no follow up of patients.

Inclusion Criteria healthy volunteers:

• Age: 6-18 years old

Exclusion Criteria:

• Treated for any gastro-intestinal symptoms
• Diarrhea in the last week before the collection of the feces sample
• Fever in the last week before collection of the feces sample
• Use of NSAIDs of Proton pump inhibitors in the last 14 days before collection feces sample.

Healthy children, aged 6-18 years old