Nosocomial diarrhea is a common problem.There are multiple ethiologies of nosocomial diarrhea in which can be divided into inflammatory and non inflammatory diarrhea. Fecal calprotectin is a good marker to identify inflammatory diarrhea in outpatient setting; for example, differentiating inflammatory bowel disease and irritable bowel syndrome. Its performance in inpatient setting has not been well established. This study aim to determine the efficacy of fecal calprotectin in distinguishing inflammatory nosocomial diarrhea from non-inflammatory nosocomial diarrhea.

This is a prospective, cross-sectional, and observational study. The patients with nosocomial diarrhea whose stool samples are sent for stool examination and Clostridium difficile toxin by their treating physicians will be recruited. Their leftover stool samples will be kept at - 80 c and will be measured for calprotectin level at the end of study. The patients will be treated by their treating physicians. They will be classified into 2 groups - inflammatory and non-inflammatory diarrhea.

The inflammatory diarrhea will be defined if 1) positive for C. difficile toxin or 2) stool WBC more than 5/HPF or 3) inflammatory mucosa or ulceration noted on colonoscopy.

The noninflammatory diarrhea will be defined if 1)negative for C. difficile toxin and 2) no WBC on stool examination and 3) dramatic response to diet adjustment or 4) no mucosal inflammation or ulceration if colonoscopy is performed

The patients who do not respond to diet modification, but do not undergo colonoscopy will be excluded because the definite diagnosis cannot be made.

Inclusion Criteria:

• age more than 18 hear
• Diarrhea more than 3 time per day after admitted in hospital more than 72 hours

Exclusion Criteria:

• intraabdominal pressure more than 12 mmHg
• patient on chemotherapy with neutropenia ,ANC less than 1,000/mm3
• patients whose definite diagnosis cannot be obtained

Inpatients in Siriraj hospital, Bangkok, Thailand