Metallic Poisons — MCQs
Frequent blushing ("erethism") is associated with which of the following poisonings?
An industrial worker presents with blue lines on gums and tremors. What is the most probable diagnosis?
Which of the following chelating agents is indicated in iron overdose?
Which of the following substances is a toxin but has also been historically used as a therapeutic emetic in poisoning management?
The triad of "saturnine" gout, hypertension and renal insufficiency is seen in poisoning with which of the following metals?
A 6-year-old boy is admitted to the ward with drowsiness, dull deep tendon reflexes and seizures. On examination the child has a line on gums and there is a history of constipation. Which will be most appropriate drug that should be used for this child?
Which of the following is most specific for arsenic poisoning ?
Vitreous humor is preserved in suspected poisoning with:
Abrus precatorius poisoning resembles which poison?
Chronic arsenic poisoning does not cause:
Metallic Poisons Indian Medical PG Practice Questions and MCQs
Question 1: Frequent blushing ("erethism") is associated with which of the following poisonings?
- A. Mercury (Correct Answer)
- B. Arsenic
- C. Lead
- D. Phenol
Explanation: ***Mercury*** - **Erethism** (frequent blushing, emotional lability, irritability, memory loss, and insomnia) is a classic neurological symptom of chronic **mercury poisoning**. - Other common signs include **tremors**, gingivitis, and acrodynia (in children). *Lead* - Lead poisoning is characterized by symptoms such as **abdominal pain**, constipation, **anemia**, wrist drop, and encephalopathy, but not typically erethism. - Neuropsychological effects in adults often manifest as cognitive deficits and peripheral neuropathy rather than emotional lability and blushing. *Phenol* - Phenol poisoning primarily causes **local corrosive effects** on tissues (burns), respiratory distress, and systemic effects like **metabolic acidosis** and kidney damage. - It does not typically present with neurological symptoms like erethism or frequent blushing. *Arsenic* - Chronic arsenic poisoning can lead to **skin lesions** (hyperkeratosis, pigmentation changes), peripheral neuropathy, and gastrointestinal symptoms. - While it can affect the nervous system, **erethism** is not a characteristic neurological symptom of arsenic toxicity.
Question 2: An industrial worker presents with blue lines on gums and tremors. What is the most probable diagnosis?
- A. Mercury
- B. Lead (Correct Answer)
- C. Arsenic poisoning
- D. Carbon monoxide
Explanation: ***Lead*** - **Blue lines on the gums (Burton's lines)** are a classic symptom of chronic lead poisoning, caused by a reaction between circulating lead and sulfur ions released by oral bacteria [2]. - **Tremors** and other neurological symptoms like *wrist drop* or *foot drop* are common manifestations of lead's neurotoxic effects [1]. *Mercury* - While **tremors** are a prominent symptom of mercury poisoning, especially *finger tremors* and *erectile dysfunction*, **blue lines on the gums** are not characteristic [3]. - Mercury poisoning is often associated with **gingivitis**, **stomatitis**, and *Erythrism* (mad hatter disease), which involves psychological changes like irritability and shyness [3]. *Arsenic poisoning* - **Arsenic poisoning** can cause **neuropathy**, but **tremors** and **blue lines on the gums** are not typical features. - It classically presents with **rain drop skin pigmentation**, **hyperkeratosis**, and **Mees' lines** (transverse white bands on nails). *Carbon monoxide* - **Carbon monoxide poisoning** primarily affects the cardiovascular and central nervous systems, leading to symptoms like **headache**, **nausea**, and cherry-red skin coloration. - **Blue lines on the gums** and **tremors** are not associated with carbon monoxide toxicity.
Question 3: Which of the following chelating agents is indicated in iron overdose?
- A. Desferrioxamine (Correct Answer)
- B. BAL
- C. Calcium Edetate
- D. DTPA
- E. Penicillamine
Explanation: ***Desferrioxamine*** - **Desferrioxamine** is a **chelate** formed by the bacterium *Streptomyces pilosus* that has a high affinity for **iron**. - It is currently the most commonly used chelating agent for **acute iron overdose** and **chronic iron overload** conditions like hemochromatosis or transfusional hemosiderosis. *BAL* - **BAL (dimercaprol)** is a chelating agent primarily used for poisoning with **arsenic**, **mercury**, and **gold**. - It works by forming stable cyclic compounds with these metals, facilitating their excretion. *Calcium Edetate* - **Calcium edetate (Calcium-EDTA)** is primarily used for **lead poisoning**. - It works by forming a stable, water-soluble complex with lead, which is then excreted by the kidneys. *DTPA* - **Diethylenetriamine pentaacetate (DTPA)** is a chelating agent primarily used for poisoning with **plutonium** and other **radioactive metals**. - It is not indicated for iron overdose. *Penicillamine* - **Penicillamine** is a chelating agent primarily used for **copper** overload (Wilson's disease) and can also be used for **lead** and **mercury** poisoning. - It is not effective for iron chelation in overdose situations.
Question 4: Which of the following substances is a toxin but has also been historically used as a therapeutic emetic in poisoning management?
- A. Thallium
- B. Copper sulphate (Correct Answer)
- C. Arsenic oxide
- D. Mercuric chloride
Explanation: ***Copper sulphate*** - **Copper sulphate** is a **potent toxin** that causes gastrointestinal irritation, hemolysis, hepatotoxicity, and acute renal failure upon ingestion. - It was **historically used as an emetic** to induce vomiting in certain poisoning cases for gastric decontamination, though this practice has been largely abandoned due to its own significant toxicity and the availability of safer alternatives. - This represents its dual nature: a poison itself, yet paradoxically used in poisoning management (not as an antidote, but as a gastric evacuant). *Thallium* - **Thallium** is a highly toxic heavy metal causing severe multi-organ failure, alopecia, peripheral neuropathy, and potentially fatal systemic toxicity. - It has **no therapeutic use** in poisoning management and is purely a toxicological concern. *Arsenic oxide* - **Arsenic oxide** (arsenic trioxide) is a well-known carcinogen and potent cellular poison that disrupts oxidative phosphorylation. - While it has modern therapeutic use in acute promyelocytic leukemia, it has **never been used in poisoning management** as an emetic or therapeutic agent. *Mercuric chloride* - **Mercuric chloride** is highly corrosive and causes severe gastrointestinal burns, acute tubular necrosis, and systemic mercury toxicity. - It is a **potent toxin with no therapeutic application** in poisoning management.
Question 5: The triad of "saturnine" gout, hypertension and renal insufficiency is seen in poisoning with which of the following metals?
- A. Arsenic
- B. Lead (Correct Answer)
- C. Copper
- D. Iron
Explanation: ***Lead*** - **Lead poisoning** is classically associated with the triad of **"saturnine" gout**, **hypertension**, and **renal insufficiency** - Lead interferes with **heme synthesis** and **renal tubular function**, and elevates **uric acid levels** leading to gout - The term "saturnine" derives from Saturn, the alchemical name for lead, and specifically refers to lead-related pathology - Chronic lead nephropathy causes progressive renal damage leading to hypertension and renal insufficiency *Arsenic* - Arsenic poisoning typically presents with **gastrointestinal symptoms** (acute watery diarrhea), skin lesions (**hyperkeratosis, melanosis, Mees' lines**), and **peripheral neuropathy** - Not primarily associated with the specific triad of gout, hypertension, and renal insufficiency *Copper* - Copper toxicity, as seen in **Wilson's disease**, manifests with hepatic dysfunction, neurological symptoms (tremor, dysarthria), and **Kayser-Fleischer rings** - Does not typically present with this specific combination of gout, hypertension, and renal insufficiency *Iron* - Acute iron poisoning causes **gastrointestinal distress**, metabolic acidosis, and shock - Chronic iron overload (**hemochromatosis**) leads to widespread organ damage (liver cirrhosis, cardiomyopathy, diabetes mellitus) but not the specific triad of saturnine gout, hypertension, and renal insufficiency
Question 6: A 6-year-old boy is admitted to the ward with drowsiness, dull deep tendon reflexes and seizures. On examination the child has a line on gums and there is a history of constipation. Which will be most appropriate drug that should be used for this child?
- A. EDTA
- B. DMSA (Correct Answer)
- C. BAL
- D. Penicillamine
Explanation: ***DMSA*** - The child's symptoms of **drowsiness**, **dull deep tendon reflexes**, **seizures**, a **gingival line**, and **constipation** are classic signs of **lead poisoning**. - **DMSA (dimercaptosuccinic acid)** is a chelating agent that is generally considered the **first-line treatment** for pediatric lead poisoning due to its oral administration, good safety profile, and efficacy in reducing lead levels. *Penicillamine* - While penicillamine is a chelating agent, it is **less commonly used** for lead poisoning in children due to a higher incidence of **side effects** compared to DMSA. - Its use is often reserved for patients who cannot tolerate other chelating agents or in specific situations. *EDTA* - **EDTA (ethylenediaminetetraacetic acid)** is a powerful chelator often used for severe lead poisoning, but it is typically administered **intravenously** or **intramuscularly**. - It is often combined with BAL to prevent redistribution of lead to the brain and is not usually the first choice for chronic, less severe lead poisoning in an ambulatory setting. *BAL* - **BAL (British Anti-Lewisite)**, or **dimercaprol**, is an oil-based intramuscular injection and is usually reserved for **severe lead encephalopathy**. - It has a high incidence of **adverse effects** and should not be used as monotherapy for lead poisoning due to the risk of redistributing lead to the brain; it is typically administered with EDTA for very high lead levels.
Question 7: Which of the following is most specific for arsenic poisoning ?
- A. Garlic-like odor in breath and urine (Correct Answer)
- B. Blue line on gums
- C. Tremors
- D. Anemia
Explanation: ***Garlic-like odor in breath and urine*** - A **garlic-like odor** in the breath and urine is a classic and highly **specific sign** of **arsenic poisoning**. - This distinctive odor is due to the **methylation of arsenic** compounds in the body. *Blue line on gums* - A **blue line on the gums**, also known as a **Burton line**, is characteristic of **lead poisoning**, not arsenic. - It results from the deposition of **lead sulfide** in the gingival tissue. *Tremors* - **Tremors** can be a symptom of various toxic exposures and neurological conditions, making them a **non-specific finding** for arsenic poisoning alone. - While **chronic arsenic poisoning** can lead to neurological symptoms, tremors are not a primary distinguishing feature. *Anemia* - **Anemia** is a common and **non-specific sign** that can be caused by many conditions, including various toxic exposures. - While chronic arsenic exposure can lead to **bone marrow suppression** and anemia, it is not specific enough for diagnosis.
Question 8: Vitreous humor is preserved in suspected poisoning with:
- A. Cyanide
- B. Morphine
- C. Alcohol (Correct Answer)
- D. Carbon monoxide
Explanation: ***Alcohol*** - **Vitreous humor** is an ideal sample for postmortem alcohol analysis due to its **sequestration** from other body fluids, which minimizes postmortem production or degradation of alcohol. - Its **avascular nature** and **slow diffusion** rates ensure that the alcohol concentration in the vitreous humor closely reflects the ante-mortem blood alcohol concentration. *Cyanide* - Sampling **vitreous humor** is generally not the primary choice for detecting cyanide because cyanide is rapidly absorbed and metabolized, making its detection more reliable in other tissues. - Cyanide can degrade in biological samples, and its concentration in the vitreous humor may not accurately reflect the lethal dose or recent exposure. *Morphine* - While **vitreous humor** can be used for opiate detection, **blood and urine** are generally preferred for initial screening and quantitative analysis of morphine. - Morphine undergoes metabolism during its elimination, and its distribution into the vitreous humor might not always accurately reflect the **pharmacodynamics** or precise time of exposure compared to blood. *Carbon monoxide* - **Carbon monoxide (CO) poisoning** is primarily diagnosed by measuring **carboxyhemoglobin levels** in blood, as CO binds avidly to hemoglobin. - The vitreous humor is not a suitable sample for detecting carbon monoxide or carboxyhemoglobin as it lacks red blood cells and hemoglobin, which are the targets of CO toxicity.
Question 9: Abrus precatorius poisoning resembles which poison?
- A. Arsenic
- B. Ricin (Correct Answer)
- C. Cyanide
- D. Thallium
Explanation: ***Ricin*** - The toxic protein in *Abrus precatorius* seeds, **abrin**, is structurally and functionally similar to **ricin** from *Ricinus communis* seeds. - Both abrin and ricin are **ribosome-inactivating proteins**, leading to similar clinical presentations of multi-organ failure. *Arsenic* - Arsenic poisoning primarily affects the GI tract, cardiovascular system, and nervous system, causing symptoms like **rice-water stools** and **garlic odor** on breath. - It works through enzyme inhibition, specifically targeting **pyruvate dehydrogenase**, unlike the ribosome-inactivating mechanism of abrin. *Cyanide* - Cyanide poisoning rapidly impairs **cellular respiration** by inhibiting cytochrome c oxidase, leading to cellular hypoxia and lactic acidosis. - Clinical features include **rapid onset of symptoms**, bright red venous blood, and **almond odor**, which are distinct from abrin poisoning. *Thallium* - Thallium poisoning is characterized by **neurological symptoms** (e.g., severe peripheral neuropathy), **alopecia**, and gastrointestinal distress. - It interferes with potassium channels and ATPase pumps, a different mechanism of toxicity compared to abrin.
Question 10: Chronic arsenic poisoning does not cause:
- A. Mesothelioma (Correct Answer)
- B. Anemia
- C. Hyperkeratosis of skin
- D. Mixed sensory and motor neuropathy
Explanation: ***Mesothelioma*** - **Mesothelioma** is a rare cancer of the lining of the lungs, abdomen, or heart, strongly associated with **asbestos exposure**, not chronic arsenic poisoning. - While arsenic is carcinogenic, it primarily causes cancers of the skin, bladder, and lung, but not typically mesothelioma. *Anemia* - **Chronic arsenic poisoning** can lead to **anemia** through various mechanisms, including **bone marrow suppression** and hemolysis. - Arsenic interferes with red blood cell production and survival, contributing to reduced hemoglobin levels. *Hyperkeratosis of skin* - One of the classic dermatological manifestations of **chronic arsenic poisoning** is **hyperkeratosis**, particularly on the palms and soles. - This often presents as thickened, discolored skin lesions following prolonged exposure. *Mixed sensory and motor neuropathy* - **Chronic arsenic exposure** is well-known to cause **peripheral neuropathy**, affecting both sensory and motor nerves. - Patients often experience numbness, tingling, weakness, and pain, especially in a "stocking-glove" distribution.
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