American Board of Internal Medicine (ABIM) Certification Practice Exam

What type of diarrhea is characterized by large-volume, watery stools that do not stop with fasting?

1. Secretory diarrhea

2. Osmotic diarrhea

3. Steatorrhea

4. Motility-related diarrhea

The correct answer is: Secretory diarrhea

The type of diarrhea characterized by large-volume, watery stools that do not stop with fasting is known as secretory diarrhea. This form of diarrhea occurs when the intestines secrete excessive amounts of electrolytes and water, leading to a high volume of discharges regardless of food intake. In contrast to osmotic diarrhea, which is typically caused by the presence of unabsorbed solutes in the intestinal lumen that draw water into the gut (and often resolves with fasting), secretory diarrhea persists even when the patient is fasting because it is driven by active secretion from the intestinal tissue rather than by the presence of unabsorbed solutes. Conditions leading to secretory diarrhea can include infections (such as cholera), certain medications, or hormonal disorders. Steatorrhea, on the other hand, refers specifically to diarrhea that contains excess fat and is associated with malabsorption syndromes, while motility-related diarrhea is usually the result of altered gut motility affecting the normal absorption of water and nutrients. However, motility-related diarrhea typically does not present with the high-volume watery stools characteristic of secretory diarrhea. Thus, the distinguishing feature of secretory diarrhea is its persistence during fasting and its ability to cause significant volume loss due to active secretion.