What is the definition of chronic diarrhea?

Definition of Chronic Diarrhea

Chronic diarrhea is defined as the abnormal passage of three or more loose or liquid stools per day and/or a daily stool weight greater than 200 g/day, persisting for more than four weeks. 1

Duration Criterion

• The four-week duration threshold is the accepted standard that distinguishes chronic from acute diarrhea and suggests a non-infectious etiology requiring further investigation. 1, 2
• This cutoff is widely accepted across gastroenterology societies, though no absolute consensus exists in the literature. 1
• Symptoms persisting beyond four weeks merit systematic evaluation for non-infectious causes including inflammatory bowel disease, microscopic colitis, celiac disease, bile acid diarrhea, malabsorption syndromes, and colorectal neoplasia. 2

Stool Frequency and Consistency

• Three or more loose or liquid stools per day represents the frequency threshold for defining diarrhea. 1
• Stool consistency (loose or liquid) is a critical component, as patients often focus on consistency rather than frequency when describing their symptoms. 1

Stool Weight Criterion

• A daily stool weight exceeding 200 g/day is the traditional quantitative definition, though this has important limitations. 1
• This 200 g/day threshold can be misleading because normal stool weights vary considerably, particularly with non-Western diets where normal volumes may exceed this value. 1
• Conversely, distal colonic pathology may produce diarrheal symptoms without increasing stool weight above 200 g/day. 1
• The 72-hour quantitative fecal fat collection is poorly reproducible, unpleasant, and its use should be discouraged in routine practice. 3

Important Clinical Distinctions

• Distinguish true diarrhea from functional bowel disorders such as irritable bowel syndrome (IBS), which affects 9-12% of the population and can overlap significantly with chronic diarrhea based on symptom reporting alone. 1
• Clarify the discrepancy between medical and lay concepts of diarrhea during initial assessment, as fecal incontinence is commonly misinterpreted as diarrhea by patients. 1
• Stool weight typically does not increase in IBS, but symptom-based diagnosis creates considerable overlap with true diarrhea since stool weight is rarely measured early in evaluation. 1

Prevalence

• Chronic diarrhea affects approximately 4-5% of Western populations when defined by excessive stool frequency without abdominal pain. 1
• It represents one of the most common reasons for referral to gastroenterology clinics. 1