Mood stabilisers: lithium: 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 · Mood stabilisers: lithium

Sample item

Which laboratory abnormality is typical of lithium-induced nephrogenic diabetes insipidus?

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

The answer and the reasoning

A. Hypernatraemia with dilute urine

Lithium can impair renal response to ADH, causing polyuria, dilute urine and hypernatraemia if water intake is inadequate.

Option by option

  • A. Hypernatraemia with dilute urine (correct)

    Correct. Free-water loss raises sodium while urine remains dilute.

  • B. Hyponatraemia with concentrated urine

    This pattern is the opposite of diabetes insipidus.

  • C. Hypercalcaemia with concentrated urine

    Concentrated urine argues against nephrogenic DI.

  • D. Hypokalaemia with acidic urine

    Potassium and urine acidity are not defining findings.

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 A, Hypernatraemia with dilute urine. Lithium can impair renal response to ADH, causing polyuria, dilute urine and hypernatraemia if water intake is inadequate.

Why is "Hyponatraemia with concentrated urine" not the answer?

This pattern is the opposite of diabetes insipidus.

Why is "Hypercalcaemia with concentrated urine" not the answer?

Concentrated urine argues against nephrogenic DI.

Why is "Hypokalaemia with acidic urine" not the answer?

Potassium and urine acidity are not defining findings.

What concept does this question test?

It tests Mood stabilisers: lithium in Psychiatry. The correct option holds because: Correct. Free-water loss raises sodium while urine remains dilute.

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 Mood stabilisers: lithium?

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.