Complications and emergencies: magnesium toxicity: practice question

A Anaesthesia question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Anaesthesia · Complications and emergencies: magnesium toxicity

Sample item

A woman with severe pre-eclampsia is on a magnesium sulphate infusion. What is the earliest clinical sign of toxicity to look for?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Loss of the patellar reflex

As magnesium levels rise, deep tendon reflexes are lost first, followed by respiratory depression and cardiac conduction block at higher levels. Reflexes, respiratory rate and urine output are monitored, and calcium gluconate is the antidote.

Option by option

  • A. Tachycardia

    Tachycardia is not the early sign of magnesium excess.

  • B. Brisk hyperreflexia

    Magnesium reduces reflexes; it does not cause hyperreflexia.

  • C. Loss of the patellar reflex (correct)

    Correct. Loss of the patellar reflex precedes respiratory depression.

  • D. Pupillary constriction

    Pupil size is not a recognised early indicator.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, Loss of the patellar reflex. As magnesium levels rise, deep tendon reflexes are lost first, followed by respiratory depression and cardiac conduction block at higher levels.

Why is "Tachycardia" not the answer?

Tachycardia is not the early sign of magnesium excess.

Why is "Brisk hyperreflexia" not the answer?

Magnesium reduces reflexes; it does not cause hyperreflexia.

Why is "Pupillary constriction" not the answer?

Pupil size is not a recognised early indicator.

What concept does this question test?

It tests Complications and emergencies: magnesium toxicity in Anaesthesia. Reflexes, respiratory rate and urine output are monitored, and calcium gluconate is the antidote.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Complications and emergencies: magnesium toxicity?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.