Nutrition: X-linked hypophosphataemic rickets: practice question

A Pediatrics 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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Pediatrics · Nutrition: X-linked hypophosphataemic rickets

Sample item

A 2-year-old boy has bowed legs, normal calcium, very low phosphate, high alkaline phosphatase and normal PTH. There is no response to usual vitamin D doses. What is the treatment?

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

The answer and the reasoning

C. Oral phosphate with calcitriol

This is X-linked dominant hypophosphataemic rickets from a PHEX mutation causing raised FGF23 and renal phosphate wasting. Treatment is oral phosphate in divided doses with calcitriol, and burosumab is an option. Nutritional vitamin D does not correct it.

Option by option

  • A. Growth hormone only

    Growth hormone is not the primary treatment.

  • B. Calcium alone

    Calcium alone does not replace phosphate.

  • C. Oral phosphate with calcitriol (correct)

    Correct. Phosphate with calcitriol is standard.

  • D. Vitamin D 2000 IU daily alone

    Ordinary vitamin D does not correct renal phosphate wasting.

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 Pediatrics question

What is the answer to this Pediatrics question?

The best answer is C, Oral phosphate with calcitriol. This is X-linked dominant hypophosphataemic rickets from a PHEX mutation causing raised FGF23 and renal phosphate wasting.

Why is "Growth hormone only" not the answer?

Growth hormone is not the primary treatment.

Why is "Calcium alone" not the answer?

Calcium alone does not replace phosphate.

Why is "Vitamin D 2000 IU daily alone" not the answer?

Ordinary vitamin D does not correct renal phosphate wasting.

What concept does this question test?

It tests Nutrition: X-linked hypophosphataemic rickets in Pediatrics. Treatment is oral phosphate in divided doses with calcitriol, and burosumab is an option. Nutritional vitamin D does not correct it.

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 Nutrition: X-linked hypophosphataemic rickets?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.