Metabolic bone: biochemistry of nutritional rickets: 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: biochemistry of nutritional rickets

Sample item

Which pattern of laboratory results is expected in nutritional vitamin D deficiency rickets?

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

The answer and the reasoning

B. Low or normal calcium, low phosphate, high alkaline phosphatase and high PTH

Vitamin D deficiency lowers calcium absorption, causing secondary hyperparathyroidism, which raises PTH and ALP and causes phosphaturia, so phosphate is low. Calcium is low or normal as PTH keeps it near normal at the expense of bone.

Option by option

  • A. Normal calcium, high phosphate, normal ALP

    High phosphate with normal ALP does not fit.

  • B. Low or normal calcium, low phosphate, high alkaline phosphatase and high PTH (correct)

    Correct. This pattern reflects secondary hyperparathyroidism.

  • C. Low calcium, high phosphate, low PTH

    Low calcium with low PTH describes hypoparathyroidism.

  • D. High calcium, high phosphate, low ALP

    High calcium and phosphate do not occur in rickets.

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, Low or normal calcium, low phosphate, high alkaline phosphatase and high PTH. Vitamin D deficiency lowers calcium absorption, causing secondary hyperparathyroidism, which raises PTH and ALP and causes phosphaturia, so phosphate is low.

Why is "Normal calcium, high phosphate, normal ALP" not the answer?

High phosphate with normal ALP does not fit.

Why is "Low calcium, high phosphate, low PTH" not the answer?

Low calcium with low PTH describes hypoparathyroidism.

Why is "High calcium, high phosphate, low ALP" not the answer?

High calcium and phosphate do not occur in rickets.

What concept does this question test?

It tests Metabolic bone: biochemistry of nutritional rickets in Orthopaedics. Calcium is low or normal as PTH keeps it near normal at the expense of bone.

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 Metabolic bone: biochemistry of nutritional rickets?

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.