Chapter 28. Transport & Metabolic Functions of the Liver
A patient suffering from severe ulcerative colitis undergoes a total colectomy with formation of a stoma. After a full recovery from surgery, and compared to his condition prior to surgery, which of the following would be expected to be decreased?
A. Ability to absorb lipids
B. Ability to clot the blood
C. Circulating levels of conjugated bile acids
The correct answer is E. Urobilinogen is formed in the colon by the action of bacteria on released bilirubin; a portion is reabsorbed and enters the enterohepatic circulation from which some urobilinogen escapes to the systemic circulation and can be excreted by the kidneys because it is less firmly bound to plasma proteins than bilirubin. Bilirubin, on the other hand, is not absorbed intact from the colon (rules out option D). Colectomy will not affect the enterohepatic circulation of conjugated bile acids because they are absorbed in the terminal ileum; if anything, the production of bile acids from the liver may rise to compensate for the loss of absorption of unconjugated bile acids that would be formed by bacteria in the colon (rules out option C). Lipid absorption should be unaffected because it takes place in the small intestine and bile acid secretion should be maintained or even increased (rules out option A). In the presumed absence of any co-occuring liver disease, the synthesis of clotting factors should occur normally (rules out option B).
A surgeon is studying new methods of liver transplantation. She performs a complete hepatectomy in an experimental animal. Before the donor liver is grafted, a rise in the blood level of which of the following would be expected?
The correct answer is E. The liver is responsible for metabolizing steroid hormones, so estrogen levels will rise. On the other hand, with loss of the glucose buffer function as well as the capacity to synthesize plasma proteins, hypoglycemia and a fall in fibrinogen would be expected with an acute reduction in liver function (rules out options A and B). 25-Hydroxycholecalciferol is also produced in the liver from cholecalciferol produced in the skin (rules out option C). Finally, bilirubin is conjugated in hepatocytes, so this reaction will not occur (rules out option D).