Metabolic bone disease: pathogenesis of renal osteodystrophy: 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 disease: pathogenesis of renal osteodystrophy

Sample item

In chronic kidney disease, which two changes are the main drivers of secondary hyperparathyroidism and renal bone disease?

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

The answer and the reasoning

D. Phosphate retention and reduced calcitriol synthesis

Failing kidneys retain phosphate and cannot make calcitriol, so intestinal calcium absorption falls. The resulting hypocalcaemia and phosphate retention stimulate parathyroid hormone secretion, causing high-turnover bone disease. FGF23 rises early as a compensatory response.

Option by option

  • A. Excess calcitriol and calcium retention

    Calcitriol is reduced in CKD, not in excess.

  • B. Low phosphate and excess vitamin D receptor activity

    Phosphate is retained, not low, in CKD.

  • C. High calcium with suppressed FGF23

    Calcium tends to fall and FGF23 rises in CKD.

  • D. Phosphate retention and reduced calcitriol synthesis (correct)

    Correct. Phosphate retention and calcitriol deficiency drive PTH secretion.

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 D, Phosphate retention and reduced calcitriol synthesis. Failing kidneys retain phosphate and cannot make calcitriol, so intestinal calcium absorption falls.

Why is "Excess calcitriol and calcium retention" not the answer?

Calcitriol is reduced in CKD, not in excess.

Why is "Low phosphate and excess vitamin D receptor activity" not the answer?

Phosphate is retained, not low, in CKD.

Why is "High calcium with suppressed FGF23" not the answer?

Calcium tends to fall and FGF23 rises in CKD.

What concept does this question test?

It tests Metabolic bone disease: pathogenesis of renal osteodystrophy in Orthopaedics. The resulting hypocalcaemia and phosphate retention stimulate parathyroid hormone secretion, causing high-turnover bone disease. FGF23 rises early as a compensatory response.

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 disease: pathogenesis of renal osteodystrophy?

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.