Child and adolescent psychiatry: preventing intellectual disability in phenylketonuria: 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 · Child and adolescent psychiatry: preventing intellectual disability in phenylketonuria

Sample item

A fair-skinned infant has a musty body odour and vomiting, and the newborn screen shows raised phenylalanine. Which intervention started early prevents intellectual disability?

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

The answer and the reasoning

C. A phenylalanine-restricted diet

In phenylketonuria, phenylalanine hydroxylase deficiency allows phenylalanine to accumulate and damage the developing brain. A diet low in phenylalanine started in the first weeks of life prevents intellectual disability.

Option by option

  • A. A ketogenic diet

    A ketogenic diet treats refractory epilepsy and does not correct this disorder.

  • B. High-dose pyridoxine for all cases

    Pyridoxine is not the treatment for classical phenylketonuria.

  • C. A phenylalanine-restricted diet (correct)

    Correct. Early dietary restriction of phenylalanine prevents brain damage.

  • D. Thyroxine replacement

    Thyroxine is the treatment of congenital hypothyroidism, which is a different cause.

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 Psychiatry question

What is the answer to this Psychiatry question?

The best answer is C, A phenylalanine-restricted diet. In phenylketonuria, phenylalanine hydroxylase deficiency allows phenylalanine to accumulate and damage the developing brain.

Why is "A ketogenic diet" not the answer?

A ketogenic diet treats refractory epilepsy and does not correct this disorder.

Why is "High-dose pyridoxine for all cases" not the answer?

Pyridoxine is not the treatment for classical phenylketonuria.

Why is "Thyroxine replacement" not the answer?

Thyroxine is the treatment of congenital hypothyroidism, which is a different cause.

What concept does this question test?

It tests Child and adolescent psychiatry: preventing intellectual disability in phenylketonuria in Psychiatry. A diet low in phenylalanine started in the first weeks of life prevents intellectual disability.

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 Child and adolescent psychiatry: preventing intellectual disability in phenylketonuria?

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.