WBR0468
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pathology, MainCategory::Pharmacology |
| Sub Category | SubCategory::Gastrointestinal |
| Prompt | [[Prompt::A 3 year old male patient is brought by his mother to the physician's office complaining that her son cannot drink milk. He is diagnosed with lactase deficiency. Which cause of diarrhea is also characterized by the same type of diarrhea associated with lactase deficiency?]] |
| Answer A | AnswerA::Use of lactulose |
| Answer A Explanation | AnswerAExp::Use of lactulose causess osmotic diarrhea. |
| Answer B | AnswerB::Carcinoid tumor |
| Answer B Explanation | AnswerBExp::Carcinoid tumor causes secretory diarrhea. |
| Answer C | AnswerC::Rectal villous adenoma |
| Answer C Explanation | AnswerCExp::Rectal villous adenoma causes secretory diarrhea. |
| Answer D | AnswerD::Use of selective serotonin reuptake inhibitors (SSRI) |
| Answer D Explanation | AnswerDExp::SSRI use causes secretory diarrhea. |
| Answer E | AnswerE::Laxative abuse |
| Answer E Explanation | AnswerEExp::Laxative abuse causes secretory diarrhea. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::Lactulose is a synthetic disaccaride that does not occur naturally. Hence, the human enterocytes do not contain enzymes to digest lactulose. As such, lactulose-induced diarrhea can be considered as a similar mechanism to that of lactase deficiency induced diarrhea. Since lactulose is not absorbed by the small intestine, the osmolar compounds drive water into the intestinal lumen and cause osmotic diarrhea.
Educational Objective: Lactulose is a synthetic disaccaride that is not digested by human enterocytes, Use of lactulose causes osmotic diarrhea in a way that mimics lactase deficiency. Reference:
Clausen MR, Mortensen PB. Lactulose, disaccarides, and colonic flora. Drugs. 1997;53(6):930-942. |
| Approved | Approved::No |
| Keyword | WBRKeyword::lactulose, WBRKeyword::secretory, WBRKeyword::osmotic, WBRKeyword::diarrhea, WBRKeyword::laxative, WBRKeyword::SSRI, WBRKeyword::rectal, WBRKeyword::villous, WBRKeyword::adenoma, WBRKeyword::rectal villous adenoma, WBRKeyword::lactase, WBRKeyword::deficiency, WBRKeyword::lactase deficiency |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |