WBR0970

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Biochemistry
Sub Category	SubCategory::General Principles
Prompt	[[Prompt::A 45-year-old man with previous history of hepatitis C infection complains of progressively increasing fatigue, loss of appetite and bleeding tendency. Physical exam reveals yellowing of the sclera and the skin in addition to an increase in the abdominal girth. During physical exam, the patient is asked to push his hands down on the midline of the abdomen, the examiner then taps one flank, while feeling on the other flank for the tap. The examiner is able to feel the tap on the other side. A set of laboratory tests is ordered. If BUN and ammonia are measured in this patient, what is the expected laboratory result respectively?]]
Answer A	AnswerA::Decreased, decreased
Answer A Explanation	AnswerAExp::In cirrhosis, hepatocytes are affected; therefore, urea cycle is not as functional as it is in a normal liver. Ammonia is not converted to urea leading to an elevated blood level of ammonia and a decreased level of blood urea level.
Answer B	AnswerB::Decreased, increased
Answer B Explanation	AnswerBExp::In cirrhosis, hepatocytes are affected; therefore, urea cycle is not as functional as it is in a normal liver. Ammonia is not converted to urea leading to an elevated blood level of ammonia and a decreased level of blood urea level.
Answer C	AnswerC::Increased, unchanged
Answer C Explanation	AnswerCExp::In cirrhosis, hepatocytes are affected; therefore, urea cycle is not as functional as it is in a normal liver. Ammonia is not converted to urea leading to an elevated blood level of ammonia and a decreased level of blood urea level.
Answer D	AnswerD::Increased, increased
Answer D Explanation	AnswerDExp::In cirrhosis, hepatocytes are affected; therefore, urea cycle is not as functional as it is in a normal liver. Ammonia is not converted to urea leading to an elevated blood level of ammonia and a decreased level of blood urea level.
Answer E	AnswerE::Unchanged, increased
Answer E Explanation	AnswerEExp::In cirrhosis, hepatocytes are affected; therefore, urea cycle is not as functional as it is in a normal liver. Ammonia is not converted to urea leading to an elevated blood level of ammonia and a decreased level of blood urea level.
Right Answer	RightAnswer::B
Explanation	[[Explanation::The patient complains of fatigue, loss of appetite and bleeding tendency in the context of hepatitis C infection. Moreover, the exam reveals jaundice and ascites as demonstrated by the fluid wave test. The fluid wave test s performed by having the patient push their hands down on the midline of the abdomen, then the examiner taps one flank, while feeling on the other flank for the tap. Fluid allows the tap to be felt on the other side. The patient's signs and symptoms are most likely due to liver cirrhosis secondary to chronic hepatitis C. Ammonia is converted in the liver to urea by a set of mitochondrial and cytoplasmic enzymes in the hepatocytes. In cirrhosis, hepatocytes are affected; therefore, urea cycle is not as functional as it is in a normal liver. Ammonia is not converted to urea leading to an elevated blood level of ammonia and a decreased level of blood urea level. Educational objective: Ammonia is converted in the liver to urea by a set of mitochondrial and cytoplasmic enzymes in the hepatocytes. In cirrhosis, the urea cycle is affected leading to an elevated blood level of ammonia and a decreased level of blood urea level. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Urea, WBRKeyword::ammonia, WBRKeyword::Cirrhosis
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::