Metabolic bone: hypophosphatasia: practice question

A Orthopaedics 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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Orthopaedics · Metabolic bone: hypophosphatasia

Sample item

A child has premature loss of deciduous teeth, rickets-like bone changes and low serum alkaline phosphatase. Which condition is this?

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

The answer and the reasoning

B. Hypophosphatasia

Hypophosphatasia is due to a mutation of the tissue non-specific alkaline phosphatase gene (ALPL), with low ALP and high levels of its substrates such as pyridoxal phosphate. It causes defective mineralisation and early tooth loss, treated with asfotase alfa.

Option by option

  • A. Hyperparathyroidism

    Hyperparathyroidism raises ALP.

  • B. Hypophosphatasia (correct)

    Correct. Low ALP with rickets and early tooth loss points to hypophosphatasia.

  • C. Fibrous dysplasia

    Fibrous dysplasia has normal or high ALP.

  • D. Vitamin D deficiency rickets

    Nutritional rickets has high ALP.

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 Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is B, Hypophosphatasia. Hypophosphatasia is due to a mutation of the tissue non-specific alkaline phosphatase gene (ALPL), with low ALP and high levels of its substrates such as pyridoxal phosphate.

Why is "Hyperparathyroidism" not the answer?

Hyperparathyroidism raises ALP.

Why is "Fibrous dysplasia" not the answer?

Fibrous dysplasia has normal or high ALP.

Why is "Vitamin D deficiency rickets" not the answer?

Nutritional rickets has high ALP.

What concept does this question test?

It tests Metabolic bone: hypophosphatasia in Orthopaedics. It causes defective mineralisation and early tooth loss, treated with asfotase alfa.

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 Metabolic bone: hypophosphatasia?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.