ABFM Toxicology and Cause of Death Analysis 3 — Questions and Answers
Question 1: A forensic toxicologist detects methamphetamine and amphetamine in postmortem blood. Which conclusion is most accurate?
- Only amphetamine was ingested; methamphetamine is an artifact
- Methamphetamine was ingested; amphetamine is its primary metabolite (Correct answer)
- Both drugs were independently ingested
- The specimen is contaminated
Correct answer: Methamphetamine was ingested; amphetamine is its primary metabolite
Amphetamine is the principal metabolite of methamphetamine via N-demethylation, so detection of both is consistent with methamphetamine ingestion alone.
Question 2: Which metal poisoning classically produces Mees' lines on fingernails and can be confirmed by inductively coupled plasma mass spectrometry (ICP-MS) of hair?
- Lead
- Mercury
- Arsenic (Correct answer)
- Cadmium
Correct answer: Arsenic
Arsenic poisoning causes Mees' lines (transverse white bands on nails) and deposits in hair chronologically, allowing ICP-MS to establish the timeline of exposure.
Question 3: In a suspected drug-facilitated sexual assault (DFSA) death, which specimen provides the longest detection window for gamma-hydroxybutyrate (GHB)?
- Blood
- Urine
- Hair (Correct answer)
- Vitreous humor
Correct answer: Hair
GHB is eliminated rapidly from blood and urine (within hours), but hair analysis can document exposure weeks to months after the event.
Question 4: A decedent who received medical care before death had blood drawn in the emergency department. Compared to postmortem blood, antemortem hospital blood is preferred because it:
- Contains higher drug concentrations due to hepatic shutdown
- Reflects true antemortem concentrations without redistribution (Correct answer)
- Is easier to extract for GC-MS analysis
- Has lower putrefactive artifact risk only
Correct answer: Reflects true antemortem concentrations without redistribution
Antemortem hospital blood collected before death reflects true circulating drug levels unaffected by postmortem redistribution, providing the most accurate pharmacokinetic snapshot.
Question 5: Which finding on postmortem chemistry most reliably supports hypoglycemia as a contributing cause of death?
- Vitreous glucose <20 mg/dL (Correct answer)
- Blood glucose <40 mg/dL on femoral sample
- Urine ketones 4+
- Vitreous glucose >200 mg/dL
Correct answer: Vitreous glucose <20 mg/dL
Vitreous glucose below 20 mg/dL is accepted as indicative of antemortem hypoglycemia because vitreous is protected from postmortem glycolysis that rapidly depletes blood glucose.
Question 6: Which substance is uniquely identified by the 'alcohol dehydrogenase' enzymatic assay producing a false positive if the sample contains isopropanol?
- Ethylene glycol
- Methanol
- Ethanol (Correct answer)
- Acetone
Correct answer: Ethanol
Enzymatic ethanol assays can cross-react with other alcohols like isopropanol, so gas chromatography headspace analysis is required to distinguish individual alcohol species.
Question 7: A manner of death is ruled undetermined when toxicological findings show a mixed drug overdose. Which factor most often prevents a ruling of accident?
- Lack of a suicide note
- Drug concentrations in a potentially lethal range without clear intent evidence (Correct answer)
- History of depression
- Prior non-fatal overdoses
Correct answer: Drug concentrations in a potentially lethal range without clear intent evidence
When drug concentrations fall in a potentially lethal range but behavioral intent cannot be established, forensic pathologists may classify manner as undetermined rather than accidental or suicidal.
ABFM Toxicology and Cause of Death Analysis 3
A forensic toxicologist detects methamphetamine and amphetamine in postmortem blood.
Which conclusion is most accurate?