Toxicology: hydrofluoric acid burn: 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: hydrofluoric acid burn

Sample item

A laboratory worker spills an acid on his hand. He has intense pain out of proportion to the minimal skin changes, and the ECG later shows a long QT interval. Which treatment targets the mechanism of toxicity?

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

The answer and the reasoning

B. Calcium gluconate

Hydrofluoric acid penetrates the skin, and the fluoride ion binds calcium and magnesium, causing deep pain, tissue necrosis and systemic hypocalcaemia with QT prolongation. Calcium gluconate applied as a gel, injected or given intravenously binds the fluoride. Water irrigation is done first.

Option by option

  • A. Sodium thiosulphate

    Sodium thiosulphate is used in cyanide poisoning.

  • B. Calcium gluconate (correct)

    Correct. Calcium binds fluoride and replaces what is lost.

  • C. Dimercaprol

    Dimercaprol is a chelator for arsenic and mercury and has no role here.

  • D. Methylene blue

    Methylene blue treats methaemoglobinaemia.

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, Calcium gluconate. Hydrofluoric acid penetrates the skin, and the fluoride ion binds calcium and magnesium, causing deep pain, tissue necrosis and systemic hypocalcaemia with QT prolongation.

Why is "Sodium thiosulphate" not the answer?

Sodium thiosulphate is used in cyanide poisoning.

Why is "Dimercaprol" not the answer?

Dimercaprol is a chelator for arsenic and mercury and has no role here.

Why is "Methylene blue" not the answer?

Methylene blue treats methaemoglobinaemia.

What concept does this question test?

It tests Toxicology: hydrofluoric acid burn in Forensic Medicine. Calcium gluconate applied as a gel, injected or given intravenously binds the fluoride. Water irrigation is done first.

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: hydrofluoric acid burn?

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.