Toxicology, Environmental & Infectious Diseases Flashcards

A child ingests iron tablets and presents 6 hours later with vomiting, abdominal pain, and bloody diarrhea. Which laboratory finding best indicates systemic iron toxicity?

Answer: Anion gap metabolic acidosis

An anion gap metabolic acidosis reflects mitochondrial dysfunction from free radical damage and is a marker of systemic iron toxicity requiring deferoxamine.

A patient develops diffuse muscle pain, dark urine, and AKI after a severe rattlesnake envenomation. Which complication is most directly responsible for the renal injury?

Answer: Myoglobinuria from venom-induced rhabdomyolysis

Crotalid venom causes myonecrosis and rhabdomyolysis; the resulting myoglobinuria precipitates in renal tubules and causes acute tubular necrosis.

Which of the following is the MOST appropriate management of severe hypothermia (core temp 25°C) with ventricular fibrillation refractory to three defibrillation attempts?

Answer: Continue CPR and withhold further shocks until rewarmed to ≥30°C

In severe hypothermia, pharmacologic and electrical therapies are largely ineffective below 30°C; CPR should be maintained and rewarming prioritized before repeating defibrillation.

A patient with HIV and CD4 count of 60/µL presents with headache, fever, and altered mentation. India ink stain of the CSF is positive. What is the first-line induction therapy?

Answer: Amphotericin B deoxycholate + flucytosine

Cryptococcal meningitis induction therapy requires amphotericin B plus flucytosine for at least 2 weeks to achieve fungal clearance before consolidation with fluconazole.

After a house fire, a victim presents with confusion, cherry-red skin, and carboxyhemoglobin of 28%. What is the half-life of COHb with 100% normobaric oxygen?

Answer: ~60–90 minutes

100% normobaric oxygen reduces the carboxyhemoglobin half-life from ~5 hours on room air to approximately 60–90 minutes.

A patient is found unconscious with empty bottles of amitriptyline and alcohol. ECG shows a QRS of 140 ms and right axis deviation of the terminal 40 ms. What is the most appropriate initial treatment?

Answer: Sodium bicarbonate 1–2 mEq/kg IV bolus

Sodium bicarbonate narrows the QRS in tricyclic antidepressant overdose by increasing serum sodium and alkalinizing the blood, reversing sodium channel blockade.

Which of the following presentations is MOST consistent with black widow spider envenomation rather than brown recluse envenomation?

Answer: Diffuse muscle cramping, diaphoresis, and severe abdominal rigidity

Latrodectus (black widow) venom causes alpha-latrotoxin-induced neurotransmitter release, producing the classic latrodectism: painful muscle cramping, diaphoresis, and autonomic instability.