Free Medical Toxicology Practice Questions

Question 1

During morning rounds, a patient who received intravenous acetylcysteine for acetaminophen poisoning is eating normally and has no encephalopathy. Treatment was extended beyond the initial course because of liver injury. Acetaminophen is now below 5 mcg/mL; AST and ALT have each fallen 60% from their peaks, although both remain above 1,000 U/L. INR has fallen to 1.4, and creatinine, lactate, pH, and phosphate have normalized. What should be done with the acetylcysteine infusion?

Accepted Answer

Discontinue it while continuing appropriate clinical and laboratory follow-up

Answer

Continue it until both aminotransferases return to their reference ranges

Answer

Repeat the loading dose because substantial aminotransferase elevation persists

Answer

Continue it until the INR is below 1.1 on two successive measurements

Question 2

A 54-year-old with a sustained-release verapamil overdose remains hypotensive at 68/42 mm Hg after an appropriate fluid challenge, intravenous calcium, atropine, and initiation of norepinephrine. Heart rate is 46/min, glucose is 286 mg/dL, and bedside echocardiography shows markedly depressed left ventricular contraction. Which additional treatment should take priority?

Accepted Answer

High-dose insulin with glucose and potassium monitoring

Answer

Transvenous pacing to restore cardiac output

Answer

Intravenous lipid emulsion as the next resuscitative infusion

Answer

An intravenous glucagon infusion as the next inotropic adjunct

Question 3

An occupational clinic receives an elevated total urinary arsenic result from a patient evaluated for nonspecific fatigue. The 24-hour collection began the morning after a large seafood meal. Examination, blood count, renal function, and liver tests are normal; no convincing occupational or drinking-water source has been identified. The laboratory can perform additional testing on the stored specimen. Which analysis would best clarify the toxicologic significance of the result?

Accepted Answer

Arsenic speciation of the stored 24-hour urine sample

Answer

A blood arsenic measurement to estimate the patient's tissue burden

Answer

Hair arsenic analysis to distinguish dietary from inorganic exposure

Answer

A urinary arsenic measurement after a chelating-agent challenge

Question 4

After an amitriptyline overdose, an adult has a generalized seizure that stops with a benzodiazepine. The airway is secured and oxygenation is adequate. ECG now shows sinus tachycardia with a QRS duration of 148 ms and a prominent terminal R wave in aVR; blood pressure is 76/40 mm Hg. Select the initial intravenous treatment directed at this conduction abnormality.

Accepted Answer

Sodium bicarbonate bolus

Answer

Amiodarone loading dose

Answer

Magnesium sulfate infusion

Answer

Lidocaine loading dose

Question 5

A previously well 3-year-old coughs and chokes immediately after swallowing lamp oil. Four hours later, temperature is 38.2 C, respiratory rate is 34/min, and oxygen saturation is 92% on room air, improving with low-flow oxygen. Chest radiography shows patchy dependent opacities. There was no preceding respiratory illness. In addition to admission for respiratory observation, the pulmonary treatment plan should be:

Accepted Answer

Provide supportive oxygen therapy without prophylactic antibiotics or corticosteroids

Answer

Start ampicillin-sulbactam for presumed bacterial aspiration pneumonia

Answer

Give systemic corticosteroids to prevent progression of the lung inflammation

Answer

Start antibiotics and corticosteroids while following the radiographic infiltrates

Question 6

Following decontamination for an organophosphate exposure, a farmworker is receiving ventilatory support, pralidoxime, and repeated atropine doses. Heart rate has risen to 132/min, but copious airway secretions and poor air entry persist. Pupils remain 1 mm, and limb fasciculations are still visible. Which finding is the most useful endpoint for titrating further atropine?

Accepted Answer

Control of bronchorrhea with improvement in air entry

Answer

Resolution of fasciculations and restoration of limb strength

Answer

Dilation of the pupils with return of a normal light response

Answer

Maintenance of the heart rate above 120/min between doses

Question 7

A 13-kg child may have swallowed 18 iron tablets. Each tablet's label lists 325 mg ferrous sulfate, equivalent to 65 mg elemental iron. The child vomited repeatedly during the first two hours but appears comfortable when first evaluated eight hours after the exposure. No earlier serum iron concentration was obtained. Using the maximum possible ingestion, which dose estimate and risk interpretation are correct?

Accepted Answer

90 mg/kg elemental iron; systemic toxicity remains possible despite the clinical improvement

Answer

18 mg/kg elemental iron; this low estimated dose supports discharge without further testing

Answer

450 mg/kg elemental iron; the calculated dose alone establishes a need for immediate chelation

Answer

90 mg/kg elemental iron; resolution of vomiting excludes a subsequent systemic phase

Question 8

At triage, a man who usually drinks heavily throughout the day reports sharply reducing his intake during the past 18 hours. He is alert but tremulous and diaphoretic, with a pulse of 124/min and blood pressure of 166/98 mm Hg. Ethanol is 180 mg/dL, glucose is normal, and there is no evidence of head injury or infection. He previously had a seizure during an attempt to stop drinking. Which approach addresses his immediate risk?

Accepted Answer

Begin benzodiazepine treatment with monitoring despite the measurable ethanol concentration

Answer

Observe without withdrawal medication until the ethanol concentration becomes undetectable

Answer

Use clonidine alone to suppress the tachycardia and hypertension

Answer

Use phenytoin prophylaxis because of his previous withdrawal-associated seizure

Question 9

A nonsmoker at 28 weeks' gestation develops headache and nausea while a faulty heater is operating in her home. The fire department confirms elevated indoor carbon monoxide. After 90 minutes of 100% oxygen, she feels well and her carboxyhemoglobin is 7%. How should the low post-treatment concentration influence further care?

Accepted Answer

Continue 100% oxygen and obtain hyperbaric consultation because fetal risk may persist

Answer

Stop oxygen and discharge her because the symptoms and maternal concentration have improved

Answer

Exclude hyperbaric treatment because the measured maternal concentration is below 25%

Answer

Switch to low-flow oxygen until maternal pulse oximetry confirms complete carbon monoxide clearance

Question 10

Two people develop severe vomiting and watery diarrhea 10 hours after eating foraged mushrooms. Their gastrointestinal symptoms diminish the next day, but one returns at 36 hours with AST 3,800 U/L, ALT 4,200 U/L, and INR 2.6. There has been no salivation, bronchorrhea, seizure, or dominant renal injury. Which toxic mechanism best accounts for this sequence?

Accepted Answer

RNA polymerase II inhibition by an amatoxin

Answer

Muscarinic receptor stimulation by muscarine

Answer

Pyridoxal phosphate depletion by a gyromitrin metabolite

Answer

Renal tubular injury caused by orellanine

Free Medical Toxicology Practice Questions

Domain 1: Analgesics and Anti-Inflammatory Agents

Question 1

Domain 2: Analytical Toxicology

Question 2

Domain 8: Cardiovascular Agents

Question 3

Domain 9: Chemical Dependency

Question 4

Domain 11: CNS Drugs and Muscle Relaxing Agents

Question 5

Domain 12: Environmental Toxicology

Question 6

Domain 17: Hydrocarbons

Question 7

Domain 19: Natural Products

Question 8

Domain 20: Pesticides

Question 9

Domain 24: Vitamins, Minerals, Bone Disease, Endocrine Agents

Question 10

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