Toxicology: lithium toxicity: practice question

A Forensic Medicine 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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Forensic Medicine · Toxicology: lithium toxicity

Sample item

A man on long-term lithium for bipolar disorder develops gastroenteritis, then a coarse tremor, ataxia, vomiting and confusion. The serum lithium level is markedly raised and renal function is poor. Which treatment removes the drug most effectively?

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

The answer and the reasoning

B. Haemodialysis

Lithium is a small, water-soluble ion with little protein binding, and it is cleared by the kidney. In severe toxicity, particularly with neurological signs or renal impairment, haemodialysis is the most effective treatment. Charcoal does not bind lithium, and alkaline diuresis does not hasten its excretion.

Option by option

  • A. Gastric lavage

    Gastric lavage is of little use in a chronic toxicity where the drug has already been absorbed.

  • B. Haemodialysis (correct)

    Correct. Lithium is small and dialysable, so dialysis clears it best.

  • C. Forced alkaline diuresis

    Alkalinisation helps salicylates, not lithium.

  • D. Activated charcoal

    Activated charcoal adsorbs lithium poorly.

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 Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is B, Haemodialysis. Lithium is a small, water-soluble ion with little protein binding, and it is cleared by the kidney.

Why is "Gastric lavage" not the answer?

Gastric lavage is of little use in a chronic toxicity where the drug has already been absorbed.

Why is "Forced alkaline diuresis" not the answer?

Alkalinisation helps salicylates, not lithium.

Why is "Activated charcoal" not the answer?

Activated charcoal adsorbs lithium poorly.

What concept does this question test?

It tests Toxicology: lithium toxicity in Forensic Medicine. In severe toxicity, particularly with neurological signs or renal impairment, haemodialysis is the most effective treatment. Charcoal does not bind lithium, and alkaline diuresis does not hasten its excretion.

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 Toxicology: lithium toxicity?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic Medicine 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.