Toxicology: thallium poisoning: 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.

Try it

Forensic Medicine · Toxicology: thallium poisoning

Sample item

A man develops severe painful paraesthesias in the feet, then loses scalp hair about 2 weeks after ingesting a rodenticide. Which antidote is used?

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

The answer and the reasoning

C. Prussian blue

Thallium poisoning causes gastroenteritis followed by painful ascending neuropathy and alopecia after 2 to 3 weeks. Prussian blue (ferric hexacyanoferrate) binds thallium in the gut and interrupts its enterohepatic recirculation, with haemodialysis in severe cases. It is also used for radioactive caesium.

Option by option

  • A. Physostigmine

    Physostigmine reverses anticholinergic toxicity.

  • B. Dimercaprol

    Dimercaprol is a chelator for arsenic, mercury and lead and may redistribute thallium.

  • C. Prussian blue (correct)

    Correct. Prussian blue traps thallium in the gut.

  • D. Deferoxamine

    Deferoxamine is the iron chelator.

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.

More Forensic Medicine questions

Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is C, Prussian blue. Thallium poisoning causes gastroenteritis followed by painful ascending neuropathy and alopecia after 2 to 3 weeks.

Why is "Physostigmine" not the answer?

Physostigmine reverses anticholinergic toxicity.

Why is "Dimercaprol" not the answer?

Dimercaprol is a chelator for arsenic, mercury and lead and may redistribute thallium.

Why is "Deferoxamine" not the answer?

Deferoxamine is the iron chelator.

What concept does this question test?

It tests Toxicology: thallium poisoning in Forensic Medicine. Prussian blue (ferric hexacyanoferrate) binds thallium in the gut and interrupts its enterohepatic recirculation, with haemodialysis in severe cases. It is also used for radioactive caesium.

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 Toxicology: thallium poisoning?

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.