Heavy metal poisoning – lead, mercury, arsenic – management MCQs With Answer

Heavy metal poisoning – lead, mercury, arsenic – management MCQs With Answer

Heavy metal poisoning is a critical topic for B.Pharm students covering lead, mercury and arsenic toxicity, clinical features, diagnosis and pharmacological management. This introduction highlights key terms: lead poisoning, mercury toxicity, arsenic poisoning, chelation therapy, EDTA, dimercaprol (BAL), succimer (DMSA), DMPS, pharmacokinetics, biomarkers and monitoring. Understanding mechanisms—enzymatic inhibition, sulfhydryl binding—and evidence-based chelation strategies is essential for safe patient care. Emphasis is on therapeutic indications, contraindications, monitoring parameters and adverse effects of antidotes. Strong grasp of these concepts prepares you for clinical decision-making and rational drug therapy. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which chelating agent is preferred for severe lead encephalopathy?

• Oral succimer (DMSA)
• Intravenous calcium disodium EDTA with dimercaprol
• Penicillamine alone
• Deferoxamine

Correct Answer: Intravenous calcium disodium EDTA with dimercaprol

Q2. Lead poisoning typically causes which classic hematologic finding?

• Megaloblastic anemia
• Basophilic stippling of red blood cells
• Spherocytosis
• Leukocytosis with eosinophilia

Correct Answer: Basophilic stippling of red blood cells

Q3. Which biomarker is most commonly used to assess recent lead exposure?

• Urinary arsenic
• Whole blood lead level
• Hair mercury concentration
• Serum ferritin

Correct Answer: Whole blood lead level

Q4. Dimercaprol (BAL) is contraindicated or used cautiously in which condition?

• Hypertension and myocardial disease
• Iron deficiency anemia
• Renal calculi
• Hypothyroidism

Correct Answer: Hypertension and myocardial disease

Q5. Which mechanism best explains arsenic toxicity at the cellular level?

• Inhibition of ferrochelatase causing porphyrin accumulation
• Binding to sulfhydryl groups and inhibition of pyruvate dehydrogenase
• Oxidative phosphorylation uncoupling through complex IV inhibition
• Competitive inhibition of acetylcholinesterase

Correct Answer: Binding to sulfhydryl groups and inhibition of pyruvate dehydrogenase

Q6. Which chelator is an oral agent recommended for moderate lead poisoning in children?

• Calcium disodium EDTA IV
• Succimer (DMSA)
• Dimercaprol (BAL)
• Piridoxine

Correct Answer: Succimer (DMSA)

Q7. Which clinical syndrome is most characteristic of chronic inorganic mercury exposure?

• Erythema multiforme
• Erethism: behavioral changes, irritability and memory loss
• Cholestatic jaundice
• Bronchospasm and wheeze

Correct Answer: Erethism: behavioral changes, irritability and memory loss

Q8. Which specimen is most useful for diagnosing chronic arsenic exposure?

• Acute serum arsenic level
• Urine arsenic collected immediately
• Hair and nail arsenic analysis
• Saliva arsenic concentration

Correct Answer: Hair and nail arsenic analysis

Q9. Which chelating agent is effective for both arsenic and mercury poisoning and can be given intramuscularly?

• Penicillamine
• Dimercaprol (BAL)
• Deferasirox
• Edetate calcium disodium (CaNa2EDTA)

Correct Answer: Dimercaprol (BAL)

Q10. Which laboratory change is typical in lead-induced anemia?

• Macrocytosis with low MCV
• Microcytic hypochromic anemia with elevated free erythrocyte protoporphyrin
• Hemolytic anemia with elevated haptoglobin
• Pancytopenia due to marrow aplasia

Correct Answer: Microcytic hypochromic anemia with elevated free erythrocyte protoporphyrin

Q11. Methylmercury exposure (e.g., fish) is most associated with which effect?

• Acute cholinergic crisis
• Neurodevelopmental deficits and cerebral palsy-like features in fetuses
• Immediate hemolysis
• Renal tubular acidosis

Correct Answer: Neurodevelopmental deficits and cerebral palsy-like features in fetuses

Q12. Which chelator is preferred for severe inorganic mercury poisoning presenting with acute renal failure?

• Succimer (DMSA)
• Dimercaprol (BAL) often followed by DMSA or DMPS
• Calcium EDTA alone
• Penicillamine only

Correct Answer: Dimercaprol (BAL) often followed by DMSA or DMPS

Q13. Which finding on an ECG may be seen in acute arsenic poisoning?

• Short PR interval
• Prolonged QT interval and risk of torsades de pointes
• Delta waves characteristic of WPW
• Peaked T waves only

Correct Answer: Prolonged QT interval and risk of torsades de pointes

Q14. EDTA chelation for lead removes lead primarily from which compartment?

• Bone stores
• Soft tissues and circulating blood lead
• Hair and nails
• Lungs

Correct Answer: Soft tissues and circulating blood lead

Q15. Which monitoring parameter is essential during EDTA chelation therapy?

• Serum magnesium only
• Urine glucose
• Renal function (serum creatinine) and electrolytes
• Thyroid function tests

Correct Answer: Renal function (serum creatinine) and electrolytes

Q16. Which occupational source is most commonly associated with adult lead exposure?

• Dental amalgam polishing
• Battery manufacturing and recycling
• Textile dyeing
• Glass blowing

Correct Answer: Battery manufacturing and recycling

Q17. Which test differentiates recent arsenic exposure from organic dietary arsenic?

• Speciation of urinary arsenic (inorganic vs organic)
• Serum creatinine measurement
• Baseline CBC
• Chest X-ray

Correct Answer: Speciation of urinary arsenic (inorganic vs organic)

Q18. Which adverse effect is commonly associated with oral succimer (DMSA)?

• Severe hyperkalemia
• Gastrointestinal upset and transient elevations in liver enzymes
• Pulmonary fibrosis
• Seizures in all patients

Correct Answer: Gastrointestinal upset and transient elevations in liver enzymes

Q19. For which heavy metal is chelation typically least effective in reversing neurotoxic effects once established?

• Inorganic arsenic
• Lead
• Methylmercury (organic mercury)
• Cadmium

Correct Answer: Methylmercury (organic mercury)

Q20. Which clinical sign is strongly suggestive of chronic arsenic exposure?

• Blue sclera
• Cutaneous hyperkeratosis and raindrop pigmentation
• Bullous pemphigoid
• Tendon xanthomas

Correct Answer: Cutaneous hyperkeratosis and raindrop pigmentation

Q21. Which chelator is known to increase urinary lead excretion but may redistribute lead into the brain if used alone in encephalopathy?

• Dimercaprol (BAL)
• Calcium disodium EDTA when used without dimercaprol
• Succimer (DMSA)
• Piracetam

Correct Answer: Calcium disodium EDTA when used without dimercaprol

Q22. Which enzyme activities are inhibited in lead poisoning leading to anemia?

• Glucose-6-phosphate dehydrogenase
• Delta-aminolevulinic acid dehydratase (ALAD) and ferrochelatase
• Acetylcholinesterase
• Cytochrome oxidase only

Correct Answer: Delta-aminolevulinic acid dehydratase (ALAD) and ferrochelatase

Q23. Which of the following is a non-chelation supportive measure in acute heavy metal ingestion?

• Immediate gastric lavage if within hours of ingestion and airway protected
• High-dose corticosteroids as first-line
• Insulin infusion
• Hyperbaric oxygen routinely

Correct Answer: Immediate gastric lavage if within hours of ingestion and airway protected

Q24. Which chelating agent is frequently used in Europe for mercury and arsenic and is available as an oral or IV agent (outside the US)?

• Dimercaptosuccinic acid (DMSA/succimer)
• Dimercaptopropane sulfonate (DMPS)
• Deferiprone
• Edetate disodium

Correct Answer: Dimercaptopropane sulfonate (DMPS)

Q25. Which clinical manifestation is typical of inorganic mercury acute toxicity?

• Respiratory failure after inhalation leading to pneumonitis
• Immediate hemoptysis only
• Peripheral neuropathy exclusively without renal involvement
• Chronic thyroiditis

Correct Answer: Respiratory failure after inhalation leading to pneumonitis

Q26. Which public health measure is most effective in preventing childhood lead poisoning?

• Mass chelation of all children annually
• Removal or control of lead-based paint and contaminated dust
• Routine dietary iron supplementation only
• Universal vaccination against lead

Correct Answer: Removal or control of lead-based paint and contaminated dust

Q27. Which laboratory finding is commonly elevated in lead poisoning and used to monitor therapy?

• Serum bilirubin
• Urine aminolevulinic acid (ALA) and free erythrocyte protoporphyrin
• Serum albumin
• Serum amylase

Correct Answer: Urine aminolevulinic acid (ALA) and free erythrocyte protoporphyrin

Q28. Which statement about chelation during pregnancy is most accurate?

• Chelation is always contraindicated in pregnancy
• Chelation risks must be weighed against maternal and fetal harm from heavy metals; recommended in severe poisoning
• Chelation cures all fetal neurodevelopmental damage
• Only penicillamine is safe in pregnancy

Correct Answer: Chelation risks must be weighed against maternal and fetal harm from heavy metals; recommended in severe poisoning

Q29. Which of the following toxic effects is classically associated with chronic lead exposure in adults?

• Peripheral neuropathy with wrist drop
• Hyperpigmentation of mucosa
• Acute pancreatitis only
• Excessive salivation and lacrimation only

Correct Answer: Peripheral neuropathy with wrist drop

Q30. Which antidote binds heavy metals via thiol groups and is excreted in urine, used orally for lead and arsenic?

• Deferoxamine
• Succimer (DMSA)
• Pralidoxime
• Metronidazole

Correct Answer: Succimer (DMSA)

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com