Mood stabilisers: lithium interactions: 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 interactions

Sample item

A patient stable on lithium is started on hydrochlorothiazide for hypertension, and develops tremor and nausea. Why?

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

The answer and the reasoning

C. Thiazides reduce renal lithium clearance, raising levels

Thiazides, NSAIDs, ACE inhibitors, ARBs and dehydration increase proximal tubular reabsorption of lithium, raising serum levels and risk of toxicity. Lithium is not protein bound or hepatically metabolised.

Option by option

  • A. Thiazides induce hepatic metabolism of lithium

    Lithium is not metabolised by the liver.

  • B. Thiazides increase lithium excretion

    Thiazides decrease, not increase, lithium excretion.

  • C. Thiazides reduce renal lithium clearance, raising levels (correct)

    Correct. Reduced clearance raises lithium levels.

  • D. Thiazides displace lithium from plasma proteins

    Lithium has no plasma protein binding.

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 C, Thiazides reduce renal lithium clearance, raising levels. Thiazides, NSAIDs, ACE inhibitors, ARBs and dehydration increase proximal tubular reabsorption of lithium, raising serum levels and risk of toxicity.

Why is "Thiazides induce hepatic metabolism of lithium" not the answer?

Lithium is not metabolised by the liver.

Why is "Thiazides increase lithium excretion" not the answer?

Thiazides decrease, not increase, lithium excretion.

Why is "Thiazides displace lithium from plasma proteins" not the answer?

Lithium has no plasma protein binding.

What concept does this question test?

It tests Mood stabilisers: lithium interactions in Psychiatry. Lithium is not protein bound or hepatically metabolised.

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 Mood stabilisers: lithium interactions?

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.