Toxicology

Question 1

Clinical Toxicology

Answer 1

• Determination of the presence of toxic materials as a reason for illness or symptoms
• Negative screen used for rule-out, positive screen relevant if there is clinical correlation
• Broad range of causative agents
• Rapid turnaround
• Urine most common specimen

Question 2

Forensic Toxicology

Answer 2

• Determination of the presence of toxic materials as they pertain to legal matters
• I.e. post-mortem, driving, drugs of abuse
• Onerous requirements and regulations common –> chain of custody, testimony

Question 3

Acetaminophen (Tylenol)

Answer 3

• Overdose can lead to irreversible and fatal hepatic failure –> transplant only option
• Has specific antidote Mucomyst (n-acetylcysteine)
• In excess, metabolites conjugate with proteins that damage mainly liver tissue but also kidney & heart
• Toxicity visualized on Rumack Nomogram; levels >200 are probable risk, >150 possible risk; Don’t measure samples before 4 hrs
• Measured via immunoassay (enzymatic also available with bili interference)

Question 4

Salicylates

Answer 4

• Aspirin, Salicylic Acid, Oil of Wintergreen
• Technically a prodrug –> metabolize to salicylate
• Uncouples oxidative phosphorylation, hindering ATP generation and causing metabolic acidosis
• CNS stimulation causes hyperventilation and respiratory alkalosis, Tinnitus (ear ringing)
• Measured with Trinder’s rxn: cheap and stable, Ferric ion complexes w/salicylate, needs serum blank