**Question:** Trousseau sign is positive in which poisoning -

A. Anticholinergic poisoning
B. Paracetamol poisoning
C. Calcium channel blocker poisoning
D. Glucocorticoid poisoning

**Core Concept:**

Trousseau sign is a clinical sign that occurs in certain poisonings, characterized by hypertension, hyperpnea, and hyperglycemia. This sign is named after French pathologist Pierre Trousseau and is typically seen in patients with hyperkalemia. Hyperkalemia occurs when there is an excess of potassium ions in the blood, which can result from various causes, including poisoning.

**Why the Correct Answer is Right:**

In poisoning cases, hyperkalemia can be caused by the following mechanisms:

1. **Anticholinergic poisoning:** This type of poisoning involves the inhibition of acetylcholine, a neurotransmitter involved in maintaining normal potassium balance in the body. The inhibition leads to hyperkalemia and consequently, the Trousseau sign.
2. **Calcium channel blocker poisoning:** These drugs interfere with calcium ion transport across cell membranes, leading to increased intracellular calcium levels. The excess calcium competes with potassium for the same binding sites, resulting in hyperkalemia and the Trousseau sign.

**Why Each Wrong Option is Incorrect:**

3. **Paracetamol poisoning (acetaminophen):** Paracetamol is an analgesic and antipyretic drug, commonly used for pain relief and fever reduction. Paracetamol poisoning primarily causes liver damage, not hyperkalemia or the Trousseau sign.
4. **Glucocorticoid poisoning:** Glucocorticoids are a class of hormones that regulate glucose and protein synthesis, among other functions. Poisoning usually results in hypokalemia, not hyperkalemia, and therefore, the Trousseau sign is not observed.

**Clinical Pearl:**

Understanding Trousseau sign is essential for medical students and practitioners, as it helps in differentiating among various poisonings and directing appropriate management strategies. In cases where Trousseau sign is present, it can be suggestive of anticholinergic or calcium channel blocker poisoning, which requires specific treatment approaches, such as calcium gluconate administration for calcium channel blocker poisoning and hemodialysis for anticholinergic poisoning.