CPC #1 – Acetaminophen poisoning and hepatic necrosis

Question 1

List a differential diagnosis for abdominal pain in a young male/female adult.

Answer 1

no answer

Question 2

Discuss the physiological mechanism and some causes of vomiting.

Answer 2

• Activation of vagal and sympathetic afferents

Question 3

Explain what information and implications derive from the following laboratory tests if they are abnormal: bilirubin, prothrombin time, ALT, AST, amylase.

Answer 3

Biliruin: Liver function
Prothrobin time: Extrinsic coagulation pathway
AST & ALT: Liver function or tissue damage
Amyase: Pancratic function

Question 4

Demonstrate how to use a modified Rumack-Matthew normogram for acetaminophen.

Answer 4

• Assume single ingestion
• Must time since ingestion
• Graph of toxicity versus time since digestion
• Above the line = toxic, below = not toxic

Question 5

Explain how acetaminophen is rendered toxic to hepatocytes.

Answer 5

• Hepatic necrosis

 - Overdose results in depletion of gluthione through interaction with CYP450 (60%)
  - Once gluthionin is depleted NAPQ1 is formed
 - Excess binds to thiol groups on amino acids on enzymes
 - Cell death

Question 6

State 4 mechanisms by which n-acetylcystine (NAC) prevents acetaminophen toxicity.

Answer 6

1. Can be metabolized to form gluthionine
2. Limits the formation of NAPQ1
3. Increase the ability to detoxify NAPQ1
4. Able to detoxify other subtances

Question 7

Name the cause of and treatment for hepatic encephalopathy.

Answer 7

• Liver failure results in excess ammonia which causes brain swelling and loss of consoiusness
• Treatment
o Lactulose: Acdified in the colon to try an neutrolise ammonia in the blood
o Frozen plasma: Replace thrombotic factors
o Vitamin K: Prothrombotic

Question 8

Explain the mechanism for disseminated intravascular coagulation

Answer 8

• Depletion of platelets and coagulative factors

* Deposition of fibrin in small vessels (thrombosis)