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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{Rim}} {{Alison}}
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pathology, Pharmacology
|MainCategory=Pathology, Pharmacology
Line 20: Line 20:
|MainCategory=Pathology, Pharmacology
|MainCategory=Pathology, Pharmacology
|SubCategory=Gastrointestinal
|SubCategory=Gastrointestinal
|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?
|Prompt=A 3-year-old male is brought by his mother to the physician's office because she is concerned that he cannot drink milk.  He is diagnosed with lactase deficiency.  Which cause of diarrhea is most likely characterized by the same diarrhea type associated with lactase deficiency?
   
   
|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]].
|Explanation=[[Lactulose]], a synthetic [[disaccaride]] that does not occur naturally, is unable to be digested by human [[enterocytes]]. [[Lactulose-induced diarrhea]] manifests with a  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:
|EducationalObjectives= [[Lactulose]] is a synthetic disaccharide that is not digested by human enterocytes. Ingestion of [[lactulose]] results in osmotic diarrhea, the same type that manifests in lactase deficiency.
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.
|References= Clausen MR, Mortensen PB. Lactulose, disaccarides, and colonic flora. Drugs. 1997;53(6):930-942.
 
Reference:
Clausen MR, Mortensen PB. Lactulose, disaccarides, and colonic flora. Drugs. 1997;53(6):930-942.
|AnswerA=Use of lactulose
|AnswerA=Use of lactulose


 
|AnswerAExp=Use of lactulose causes osmotic diarrhea.
|AnswerAExp=Use of lactulose causess osmotic diarrhea.
|AnswerB=Carcinoid tumor
|AnswerB=Carcinoid tumor
|AnswerBExp=Carcinoid tumor causes secretory diarrhea.
|AnswerBExp=Carcinoid tumors frequently manifest with secretory diarrhea.
|AnswerC=Rectal villous adenoma
|AnswerC=Rectal villous adenoma
|AnswerCExp=Rectal villous adenoma causes secretory diarrhea.
|AnswerCExp=Rectal villous adenoma frequently manifest with secretory diarrhea.
|AnswerD=Use of selective serotonin reuptake inhibitors (SSRI)
|AnswerD=Use of selective serotonin reuptake inhibitors (SSRI)
|AnswerDExp=SSRI use causes secretory diarrhea.
|AnswerDExp=SSRI use frequently manifest with secretory diarrhea.
|AnswerE=Laxative abuse
|AnswerE=Laxative abuse
|AnswerEExp=Laxative abuse causes secretory diarrhea.
|AnswerEExp=Laxative abuse frequently manifest with secretory diarrhea.
|RightAnswer=A
|RightAnswer=A
|WBRKeyword=lactulose, secretory, osmotic, diarrhea, laxative, SSRI, rectal, villous, adenoma, rectal villous adenoma, lactase, deficiency, lactase deficiency
|WBRKeyword=lactulose, secretory, osmotic diarrhea, laxative, SSRI, rectal, rectal villous adenoma, lactase deficiency, digestive system, excretory system, membrane transport, enzymes
|Approved=No
|Approved=Yes
}}
}}

Revision as of 14:25, 28 July 2014

 
Author [[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Alison Leibowitz)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pathology, MainCategory::Pharmacology
Sub Category SubCategory::Gastrointestinal
Prompt [[Prompt::A 3-year-old male is brought by his mother to the physician's office because she is concerned that he cannot drink milk. He is diagnosed with lactase deficiency. Which cause of diarrhea is most likely characterized by the same diarrhea type associated with lactase deficiency?]]
Answer A AnswerA::Use of lactulose
Answer A Explanation AnswerAExp::Use of lactulose causes osmotic diarrhea.
Answer B AnswerB::Carcinoid tumor
Answer B Explanation AnswerBExp::Carcinoid tumors frequently manifest with secretory diarrhea.
Answer C AnswerC::Rectal villous adenoma
Answer C Explanation AnswerCExp::Rectal villous adenoma frequently manifest with secretory diarrhea.
Answer D AnswerD::Use of selective serotonin reuptake inhibitors (SSRI)
Answer D Explanation AnswerDExp::SSRI use frequently manifest with secretory diarrhea.
Answer E AnswerE::Laxative abuse
Answer E Explanation AnswerEExp::Laxative abuse frequently manifest with secretory diarrhea.
Right Answer RightAnswer::A
Explanation [[Explanation::Lactulose, a synthetic disaccaride that does not occur naturally, is unable to be digested by human enterocytes. Lactulose-induced diarrhea manifests with a 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 disaccharide that is not digested by human enterocytes. Ingestion of lactulose results in osmotic diarrhea, the same type that manifests in lactase deficiency.
References: Clausen MR, Mortensen PB. Lactulose, disaccarides, and colonic flora. Drugs. 1997;53(6):930-942.]]

Approved Approved::Yes
Keyword WBRKeyword::lactulose, WBRKeyword::secretory, WBRKeyword::osmotic diarrhea, WBRKeyword::laxative, WBRKeyword::SSRI, WBRKeyword::rectal, WBRKeyword::rectal villous adenoma, WBRKeyword::lactase deficiency, WBRKeyword::digestive system, WBRKeyword::excretory system, WBRKeyword::membrane transport, WBRKeyword::enzymes
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