Antipsychotics: QT prolongation: practice question

A Psychiatry 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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Psychiatry · Antipsychotics: QT prolongation

Sample item

Before starting thioridazine or a high-dose of a QT-prolonging antipsychotic, which baseline test is advisable?

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

The answer and the reasoning

B. ECG and serum potassium and magnesium

Several antipsychotics prolong the QT interval and risk torsades de pointes, so a baseline ECG and electrolytes are advised, especially with cardiac disease or other QT-prolonging drugs. Hypokalaemia and hypomagnesaemia increase risk. Thioridazine carries the most notable risk.

Option by option

  • A. Chest X-ray

    A chest X-ray does not assess QT.

  • B. ECG and serum potassium and magnesium (correct)

    Correct. ECG and electrolytes assess QT risk.

  • C. Urine culture

    A urine culture is irrelevant.

  • D. Fasting prolactin alone

    Prolactin does not assess arrhythmia risk.

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 Psychiatry question

What is the answer to this Psychiatry question?

The best answer is B, ECG and serum potassium and magnesium. Several antipsychotics prolong the QT interval and risk torsades de pointes, so a baseline ECG and electrolytes are advised, especially with cardiac disease or other QT-prolonging drugs.

Why is "Chest X-ray" not the answer?

A chest X-ray does not assess QT.

Why is "Urine culture" not the answer?

A urine culture is irrelevant.

Why is "Fasting prolactin alone" not the answer?

Prolactin does not assess arrhythmia risk.

What concept does this question test?

It tests Antipsychotics: QT prolongation in Psychiatry. Hypokalaemia and hypomagnesaemia increase risk. Thioridazine carries the most notable risk.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Antipsychotics: QT prolongation?

Learn each diagnosis by its core features and its first-line treatment. Then use the flashcards and the other Psychiatry 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.