Eating disorders: metabolic complications of purging: 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 · Eating disorders: metabolic complications of purging

Sample item

A woman with bulimia nervosa who vomits daily presents with weakness and palpitations. Which acid-base and electrolyte abnormality is expected?

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

The answer and the reasoning

D. Hypokalaemic hypochloraemic metabolic alkalosis

Vomiting loses hydrochloric acid, causing metabolic alkalosis with hypochloraemia, and volume depletion causes secondary hyperaldosteronism with hypokalaemia. Laxative abuse instead produces a hyperchloraemic metabolic acidosis with hypokalaemia. Potassium disturbance can cause arrhythmia.

Option by option

  • A. Hyperkalaemic metabolic acidosis

    Hyperkalaemia and acidosis do not follow vomiting.

  • B. Hypercalcaemic metabolic acidosis

    Hypercalcaemia is not expected.

  • C. Hypernatraemic respiratory acidosis

    Respiratory acidosis is not a feature of vomiting.

  • D. Hypokalaemic hypochloraemic metabolic alkalosis (correct)

    Correct. Vomiting gives hypokalaemic hypochloraemic metabolic alkalosis.

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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What is the answer to this Psychiatry question?

The best answer is D, Hypokalaemic hypochloraemic metabolic alkalosis. Vomiting loses hydrochloric acid, causing metabolic alkalosis with hypochloraemia, and volume depletion causes secondary hyperaldosteronism with hypokalaemia.

Why is "Hyperkalaemic metabolic acidosis" not the answer?

Hyperkalaemia and acidosis do not follow vomiting.

Why is "Hypercalcaemic metabolic acidosis" not the answer?

Hypercalcaemia is not expected.

Why is "Hypernatraemic respiratory acidosis" not the answer?

Respiratory acidosis is not a feature of vomiting.

What concept does this question test?

It tests Eating disorders: metabolic complications of purging in Psychiatry. Laxative abuse instead produces a hyperchloraemic metabolic acidosis with hypokalaemia. Potassium disturbance can cause arrhythmia.

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 Eating disorders: metabolic complications of purging?

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.