Nephrology: high anion gap acidosis: practice question

A General 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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General Medicine · Nephrology: high anion gap acidosis

Sample item

Which of the following causes a high anion gap metabolic acidosis?

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

The answer and the reasoning

A. Methanol ingestion

Causes of a high gap acidosis follow the MUDPILES mnemonic: methanol, uraemia, DKA, paraldehyde or propylene glycol, isoniazid or iron, lactic acidosis, ethylene glycol and salicylates. Diarrhoea, RTA and carbonic anhydrase inhibitors give a normal gap hyperchloraemic acidosis.

Option by option

  • A. Methanol ingestion (correct)

    Correct. Methanol produces formic acid and raises the gap.

  • B. Diarrhoea

    Diarrhoea causes bicarbonate loss with normal gap.

  • C. Acetazolamide use

    Acetazolamide causes bicarbonate loss with a normal gap.

  • D. Proximal renal tubular acidosis

    Proximal RTA causes a normal gap acidosis.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is A, Methanol ingestion. Causes of a high gap acidosis follow the MUDPILES mnemonic: methanol, uraemia, DKA, paraldehyde or propylene glycol, isoniazid or iron, lactic acidosis, ethylene glycol and salicylates.

Why is "Diarrhoea" not the answer?

Diarrhoea causes bicarbonate loss with normal gap.

Why is "Acetazolamide use" not the answer?

Acetazolamide causes bicarbonate loss with a normal gap.

Why is "Proximal renal tubular acidosis" not the answer?

Proximal RTA causes a normal gap acidosis.

What concept does this question test?

It tests Nephrology: high anion gap acidosis in General Medicine. Diarrhoea, RTA and carbonic anhydrase inhibitors give a normal gap hyperchloraemic acidosis.

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 Nephrology: high anion gap acidosis?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General 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.