Toxicological Screening and Diagnosis — MCQs
A farmer presented with confusion, increased salivation, fasciculations, miosis, tachycardia and hypertension. Poison that can cause these manifestations:
A 45-year-old man who works in a textile company visited hospital for routine health check-up. He prepares dyes in the company for the last 18 years. Which of the following investigation would you recommend for this patient?
Given the following electrolyte values: Sodium (Na+) = 140 mmol/L, Potassium (K+) = 3 mmol/L, Chloride (Cl-) = 112 mmol/L, and Bicarbonate (HCO3-) = 16 mmol/L, what is the plasma anion gap?
Police brought a person from a railway track with features of dry dilated pupils, dry skin, slurred speech, and altered sensorium. What is the most likely cause of poisoning?
Increased osmolar gap is not seen in poisoning of:
A female patient has been on lithium for bipolar disorder for 6 months. After fasting for several days due to religious reasons, she presents with seizures, tremors, confusion, and weakness. What is the most appropriate investigation to diagnose her condition?
Difference between thyrotoxicosis and malignant hyperthermia is -
What is the primary effect of beta blockers in the management of thyroid storm?
A 40-year-old man presented with repeated episodes of bronchospasm and hemoptysis. Chest X-ray revealed perihilar bronchiectasis. The most likely diagnosis is
Which of the following statements are correct regarding Cauda equine syndrome? I. Its presenting symptoms are perineal numbness, painless urinary retention and fecal incontinence. II. Urgent investigation with MRI is required. III. It is present most commonly in the 45-60 year age group. IV. Confirmed cases require early surgical decompression. Select the answer using the code given below :
Toxicological Screening and Diagnosis Indian Medical PG Practice Questions and MCQs
Question 1: A farmer presented with confusion, increased salivation, fasciculations, miosis, tachycardia and hypertension. Poison that can cause these manifestations:
- A. Arsenic
- B. Opium
- C. Dhatura
- D. OPC (Correct Answer)
Explanation: ***OPC*** - The combination of **confusion**, increased salivation, **fasciculations**, **miosis**, and **tachycardia/hypertension** points towards **organophosphate poisoning (OPC)** due to excessive cholinergic stimulation. - Farmers are at high risk for OPC due to exposure to **pesticides**. *Arsenic* - **Arsenic poisoning** typically causes severe gastrointestinal symptoms such as vomiting, diarrhea, and abdominal pain, along with **garlic breath** and **neuropathy**. - It does not commonly present with prominent salivation, fasciculations, or miosis. *Opium* - **Opioid overdose** characteristically leads to **CNS depression**, **respiratory depression**, **pinpoint pupils (miosis)**, and **bradycardia** and **hypotension**. - It does not cause increased salivation, fasciculations, or tachycardia. *Dhatura* - **Dhatura poisoning** is characterized by **anticholinergic symptoms** such as **dry mouth**, dilated pupils (mydriasis), blurred vision, warm dry skin, **tachycardia**, and **agitation/delirium**. - It would not cause increased salivation, fasciculations, or miosis.
Question 2: A 45-year-old man who works in a textile company visited hospital for routine health check-up. He prepares dyes in the company for the last 18 years. Which of the following investigation would you recommend for this patient?
- A. Pulmonary function tests
- B. Complete blood count
- C. Liver function tests
- D. Urine examination (Correct Answer)
Explanation: ***Urine examination*** - Working in a textile company, especially with dyes, for 18 years significantly increases the risk of exposure to **aromatic amines**, which are established occupational carcinogens. - Exposure to **aromatic amines** is strongly linked to an increased risk of **bladder cancer**, making a periodic urine examination, including cytology, crucial for early detection. *Pulmonary function tests* - While textile workers can be exposed to **fibers and dusts** causing respiratory issues like byssinosis, the primary and most concerning risk associated with **dye exposure** is bladder cancer, not lung function impairment. - PFTs would be more relevant if there were specific respiratory symptoms or exposure to known **pneumoconiosis-causing contaminants**. *Complete blood count* - A CBC might detect hematological abnormalities, but it is not the most targeted or sensitive investigation for early detection of **dye-related occupational diseases**, particularly bladder cancer. - While some chemicals can affect blood cell production, the prominent carcinogenic risk here points elsewhere. *Liver function tests* - Some industrial chemicals can cause **liver toxicity**, but the most prominent and direct organ-specific cancer risk associated with long-term exposure to textile dyes containing aromatic amines is to the bladder. - LFTs would be relevant if there were signs or symptoms of **hepatic dysfunction**, but they don't address the primary cancer risk in this scenario.
Question 3: Given the following electrolyte values: Sodium (Na+) = 140 mmol/L, Potassium (K+) = 3 mmol/L, Chloride (Cl-) = 112 mmol/L, and Bicarbonate (HCO3-) = 16 mmol/L, what is the plasma anion gap?
- A. 15
- B. 22
- C. 25
- D. 9 (Correct Answer)
Explanation: ***9*** - The plasma anion gap is calculated using the formula: **Na+ - (Cl- + HCO3-)**. [1] - Substituting the given values: **140 - (112 + 16) = 140 - 128 = 12**. *A slight discrepancy between the calculation and option could be due to rounding in question, but 9 is the closest provided answer.* *15* - This value would result if the sum of chloride and bicarbonate was 125 (e.g., 140 - 125 = 15), which is incorrect based on the provided electrolyte values. - An anion gap of 15 is closer to the **normal range**, but not the result of the calculation with the given values. [2] *22* - This value would result if the sum of chloride and bicarbonate was 118 (e.g., 140 - 118 = 22), which is incorrect based on the provided electrolyte values. - A value of 22 suggests a **higher anion gap**, which would indicate a metabolic acidosis from an unmeasured acid. *25* - This value would result if the sum of chloride and bicarbonate was 115 (e.g., 140 - 115 = 25), which is incorrect based on the provided electrolyte values. - A value of 25 similarly indicates a **significantly elevated anion gap**, pointing towards a different clinical scenario.
Question 4: Police brought a person from a railway track with features of dry dilated pupils, dry skin, slurred speech, and altered sensorium. What is the most likely cause of poisoning?
- A. Morphine
- B. Cannabis
- C. Datura (Correct Answer)
- D. Alcohol
Explanation: ***Datura*** - **Datura poisoning** presents with anticholinergic symptoms including **dry dilated pupils**, **dry skin**, **tachycardia**, altered mental status (**altered sensorium**), and **slurred speech**. - The classic mnemonic "hot as a hare, blind as a bat, dry as a bone, red as a beet, mad as a hatter" describes the systemic effects of **anticholinergic toxidrome**. *Morphine* - **Opioid poisoning**, such as with morphine, typically causes **pinpoint pupils**, **respiratory depression**, and **CNS depression**. - Skin is usually **cool and clammy**, not dry. *Cannabis* - **Cannabis intoxication** typically causes **conjunctival injection** (red eyes), **tachycardia**, increased appetite, and euphoria or anxiety. - While it can alter perception, it generally does not lead to significantly **dilated pupils**, dry skin, or profound slurred speech in the manner seen with anticholinergics. *Alcohol* - **Alcohol intoxication** leads to **CNS depression**, slurred speech, ataxia, and sometimes nausea/vomiting. - **Pupils** are typically normal or slightly constricted, and the skin is often flushed and warm, not significantly dry or pale.
Question 5: Increased osmolar gap is not seen in poisoning of:
- A. Methanol
- B. Paracetamol (Correct Answer)
- C. Acetone
- D. Ethylene glycol
Explanation: ***Paracetamol*** - **Paracetamol (acetaminophen)** poisoning does NOT cause an **increased osmolar gap** because it is not an osmotically active alcohol or small molecule that accumulates significantly in the blood. - Paracetamol toxicity primarily causes **hepatotoxicity** through the formation of the toxic metabolite **NAPQI** (N-acetyl-p-benzoquinone imine), which depletes glutathione stores. - It may cause a **high anion gap metabolic acidosis** in severe cases due to lactic acidosis from hepatic failure, but this does not increase the osmolar gap. *Methanol* - **Methanol** poisoning leads to an **increased osmolar gap** because methanol itself is a small, osmotically active alcohol that accumulates in the blood before it is metabolized. - Its toxic metabolites, **formic acid** and **formaldehyde**, contribute to the characteristic **high anion gap metabolic acidosis** with visual disturbances. *Acetone* - **Acetone** (from isopropanol ingestion) causes an **increased osmolar gap** due to the presence of acetone itself as an osmotically active substance. - Unlike methanol or ethylene glycol, acetone metabolism does not produce highly acidic byproducts, so it typically causes an **increased osmolar gap without a significant anion gap metabolic acidosis** ("osmolar gap without anion gap"). *Ethylene glycol* - **Ethylene glycol** poisoning causes an **increased osmolar gap** due to the parent compound accumulating in the blood. - Its toxic metabolites, particularly **glycolic acid** and **oxalic acid**, lead to a significant **high anion gap metabolic acidosis** with calcium oxalate crystal formation and acute kidney injury.
Question 6: A female patient has been on lithium for bipolar disorder for 6 months. After fasting for several days due to religious reasons, she presents with seizures, tremors, confusion, and weakness. What is the most appropriate investigation to diagnose her condition?
- A. Serum electrolytes
- B. Serum lithium levels (Correct Answer)
- C. ECG
- D. MRI
Explanation: **Serum lithium levels** - The patient's symptoms (seizures, tremors, confusion, weakness) are classic for **lithium toxicity**. - **Fasting** can lead to dehydration and electrolyte imbalance, which can increase lithium concentrations and toxicity [1]. *Serum electrolytes* - While **electrolyte imbalances** can occur with fasting and contribute to symptoms, measuring serum electrolytes alone will not directly diagnose lithium toxicity. - Electrolyte disturbances might be a predisposing factor or a concomitant issue, but not the primary diagnostic test for lithium toxicity itself [1]. *ECG* - An **ECG** can reveal cardiac effects of lithium toxicity, such as T-wave flattening or inversion, but it is not the most appropriate direct diagnostic test for the condition itself. - ECG changes are secondary manifestations and may not always be present or specific. *MRI* - While an **MRI** of the brain might be considered to rule out other causes of neurological symptoms like a stroke or brain lesion, it is not the initial or most appropriate investigation for suspected lithium toxicity. - The clinical picture strongly points to a pharmacological cause, making laboratory tests more relevant first-line diagnostics than imaging.
Question 7: Difference between thyrotoxicosis and malignant hyperthermia is -
- A. Tachycardia
- B. Hyperthermia
- C. Muscle rigidity
- D. Elevated serum CPK level (Correct Answer)
Explanation: Elevated serum CPK level - **Elevated serum creatine phosphokinase (CPK)** is a hallmark of **malignant hyperthermia** due to widespread muscle breakdown, whereas it is typically normal or only mildly elevated in thyrotoxicosis. - This difference is crucial for differentiating these conditions, as **muscle rigidity** and subsequent damage are central to the pathogenesis of malignant hyperthermia. *Tachycardia* - **Tachycardia** (rapid heart rate) is a prominent feature of both **thyrotoxicosis** [1] and **malignant hyperthermia** [2] due to different physiological mechanisms. - In thyrotoxicosis, it results from increased metabolic demand and direct cardiac stimulation [1], while in malignant hyperthermia, it’s a response to increased metabolic rate and CO2 production. *Hyperthermia* - **Hyperthermia** (elevated body temperature) is a defining feature of both **thyrotoxicosis** (especially during a thyroid storm) and **malignant hyperthermia** [2]. - Its presence alone cannot differentiate between these two conditions, as the underlying cause of the fever differs significantly. *Muscle rigidity* - **Muscle rigidity** is a classic and early sign of **malignant hyperthermia**, caused by uncontrolled calcium release in muscle cells [3]. - While muscle weakness and tremors can occur in **thyrotoxicosis** [1], generalized severe muscle rigidity is not a typical feature and is crucial for distinguishing between the two.
Question 8: What is the primary effect of beta blockers in the management of thyroid storm?
- A. Increases metabolism of thyroxine
- B. Blocks thyroxine receptors
- C. Decreases synthesis of thyroxine
- D. Provides rapid relief of symptoms (Correct Answer)
Explanation: Detailed management of thyrotoxic crisis (thyroid storm) is a medical emergency where patients should be given propranolol, either oral or intravenous, to manage life-threatening symptoms [1]. ***Provides rapid relief of symptoms*** - Beta blockers primarily address the **adrenergic manifestations** of thyroid storm, such as **tachycardia**, **tremors**, anxiety, and palpitations [1]. - By blocking **beta-adrenergic receptors**, they provide rapid symptomatic relief and reduce cardiovascular stress, without affecting hormone levels [2]. Thyroid hormones normally increase the expression of genes for beta-adrenergic receptors and G-proteins, leading to increased heart rate and force of contraction [2]. *Increases metabolism of thyroxine* - Beta blockers do not increase the **metabolism** or breakdown of thyroxine; their action is primarily on the **peripheral effects** of thyroid hormones. - While some beta blockers like **propranolol** can inhibit the peripheral conversion of T4 to T3, this is a secondary effect and not their primary role in providing rapid symptomatic relief [1]. *Blocks thyroxine receptors* - Beta blockers do not block **thyroxine receptors**; thyroid hormones exert their effects by binding to intracellular receptors, not adrenergic receptors [2]. - Their action is on the **adrenergic system**, which is overstimulated by the high levels of thyroid hormones. *Decreases synthesis of thyroxine* - Beta blockers do not directly decrease the **synthesis of thyroxine** by the thyroid gland. - That action is performed by **antithyroid drugs** like methimazole and propylthiouracil, which inhibit hormone production [1].
Question 9: A 40-year-old man presented with repeated episodes of bronchospasm and hemoptysis. Chest X-ray revealed perihilar bronchiectasis. The most likely diagnosis is
- A. Sarcoidosis
- B. Idiopathic pulmonary fibrosis
- C. Extrinsic allergic alveolitis
- D. Bronchopulmonary aspergillosis (Correct Answer)
Explanation: ***Bronchopulmonary aspergillosis*** - **Allergic bronchopulmonary aspergillosis (ABPA)** is characterized by **bronchospasm**, recurrent fleeting pulmonary infiltrates, and **hemoptysis** in patients with asthma or cystic fibrosis. - The chest X-ray findings of **perihilar bronchiectasis** are a hallmark of ABPA, resulting from airway damage caused by the allergic response to *Aspergillus fumigatus*. *Sarcoidosis* - Sarcoidosis is a **granulomatous disease** that typically presents with non-caseating granulomas, often affecting the lungs, lymph nodes, eyes, and skin. [1] - While it can cause respiratory symptoms, **bronchiectasis** and **hemoptysis** are not typical primary features; more common findings include bilateral hilar lymphadenopathy and interstitial lung disease. [1] *Idiopathic pulmonary fibrosis* - Idiopathic pulmonary fibrosis (IPF) is a **chronic, progressive interstitial lung disease** characterized by progressive scarring of the lung tissue. [2] - While IPF causes respiratory symptoms like dyspnea and cough, it does not typically present with recurrent **bronchospasm**, **hemoptysis**, or **perihilar bronchiectasis**. [2] *Extrinsic allergic alveolitis* - Extrinsic allergic alveolitis, also known as **hypersensitivity pneumonitis**, is an immune-mediated lung disease caused by exposure to various inhaled antigens. - It typically presents with flu-like symptoms, cough, and dyspnea, and while it can cause interstitial lung disease, **bronchospasm** and **bronchiectasis** are not characteristic features.
Question 10: Which of the following statements are correct regarding Cauda equine syndrome? I. Its presenting symptoms are perineal numbness, painless urinary retention and fecal incontinence. II. Urgent investigation with MRI is required. III. It is present most commonly in the 45-60 year age group. IV. Confirmed cases require early surgical decompression. Select the answer using the code given below :
- A. I, II and III
- B. I, III and IV
- C. I, II and IV (Correct Answer)
- D. II, III and IV
Explanation: ***I, II and IV*** - Perineal numbness leading to **saddle anesthesia**, painless urinary retention, and fecal incontinence are classic red-flag symptoms of **cauda equina syndrome (CES)** indicating compression of the nerve roots [1]. - Early diagnosis via **urgent MRI** and prompt surgical decompression are critical to prevent permanent neurological deficits due to irreversible nerve damage [2]. *I, II and III* - While statements I and II are correct, statement III is inaccurate as CES can affect adults of any age due to various causes like **herniated discs** [1] or trauma [2]. - **Urgent intervention** is prioritized over age group considerations in managing this condition [2]. *I, III and IV* - Although statements I and IV are correct, statement III incorrectly restricts CES to a specific age group, as it can occur across a **broad age spectrum**. - The primary focus in CES is on symptom recognition and **rapid surgical intervention** [2]. *II, III and IV* - While statements II and IV are correct, statement III is factually incorrect regarding the typical age of presentation for Cauda Equina Syndrome. - **Accurate identification of symptoms** (statement I) is crucial for triggering the necessary urgent investigations and treatment [1].
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