Metabolic bone disease: hungry bone syndrome: 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.

Try it

Orthopaedics · Metabolic bone disease: hungry bone syndrome

Sample item

A 45-year-old with severe primary hyperparathyroidism and brown tumours has a parathyroidectomy. Three days later he has perioral tingling and carpopedal spasm. Serum calcium and phosphate are both low, with PTH not suppressed. What is the mechanism?

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

The answer and the reasoning

A. Rapid uptake of calcium and phosphate by remineralising bone

Hungry bone syndrome follows parathyroidectomy when the fall in PTH switches off resorption but formation continues, and bone avidly takes up calcium, phosphate and magnesium. It is more likely with high pre-operative alkaline phosphatase and bone disease. Treatment is high-dose calcium and calcitriol, with magnesium replacement.

Option by option

  • A. Rapid uptake of calcium and phosphate by remineralising bone (correct)

    Correct. Remineralising bone takes up calcium and phosphate, with low levels of both and a PTH that is not low.

  • B. Permanent hypoparathyroidism from removal of all glands

    After complete gland removal the calcium is low but phosphate is high, and PTH is low or undetectable.

  • C. End-organ resistance to PTH

    End-organ resistance, as in pseudohypoparathyroidism, causes low calcium with high phosphate and high PTH.

  • D. Vitamin D toxicity

    Vitamin D toxicity raises calcium and phosphate rather than lowering them.

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.

More Orthopaedics questions

Questions about this Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is A, Rapid uptake of calcium and phosphate by remineralising bone. Hungry bone syndrome follows parathyroidectomy when the fall in PTH switches off resorption but formation continues, and bone avidly takes up calcium, phosphate and magnesium.

Why is "Permanent hypoparathyroidism from removal of all glands" not the answer?

After complete gland removal the calcium is low but phosphate is high, and PTH is low or undetectable.

Why is "End-organ resistance to PTH" not the answer?

End-organ resistance, as in pseudohypoparathyroidism, causes low calcium with high phosphate and high PTH.

Why is "Vitamin D toxicity" not the answer?

Vitamin D toxicity raises calcium and phosphate rather than lowering them.

What concept does this question test?

It tests Metabolic bone disease: hungry bone syndrome in Orthopaedics. It is more likely with high pre-operative alkaline phosphatase and bone disease. Treatment is high-dose calcium and calcitriol, with magnesium replacement.

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 disease: hungry bone syndrome?

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.