Nephrology: CKD mineral bone disorder: practice question

A General Medicine 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

General Medicine · Nephrology: CKD mineral bone disorder

Sample item

A patient with advanced CKD has serum calcium 7.8 mg/dL, phosphate 7.4 mg/dL and markedly elevated PTH. What is the mechanism?

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

The answer and the reasoning

B. Phosphate retention and reduced calcitriol production lead to secondary hyperparathyroidism

Reduced GFR retains phosphate and kidneys lose 1-alpha-hydroxylase activity, reducing calcitriol and calcium absorption. The low calcium and high phosphate stimulate PTH, producing secondary hyperparathyroidism and renal osteodystrophy. Treatment includes phosphate binders, active vitamin D and calcimimetics.

Option by option

  • A. Ectopic PTH secretion

    Ectopic PTH is very rare and would raise calcium.

  • B. Phosphate retention and reduced calcitriol production lead to secondary hyperparathyroidism (correct)

    Correct. This is the mechanism of CKD-MBD.

  • C. Primary parathyroid adenoma

    Primary hyperparathyroidism has high calcium.

  • D. Excess vitamin D intake

    Vitamin D excess raises calcium.

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 General Medicine questions

Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is B, Phosphate retention and reduced calcitriol production lead to secondary hyperparathyroidism. Reduced GFR retains phosphate and kidneys lose 1-alpha-hydroxylase activity, reducing calcitriol and calcium absorption.

Why is "Ectopic PTH secretion" not the answer?

Ectopic PTH is very rare and would raise calcium.

Why is "Primary parathyroid adenoma" not the answer?

Primary hyperparathyroidism has high calcium.

Why is "Excess vitamin D intake" not the answer?

Vitamin D excess raises calcium.

What concept does this question test?

It tests Nephrology: CKD mineral bone disorder in General Medicine. The low calcium and high phosphate stimulate PTH, producing secondary hyperparathyroidism and renal osteodystrophy. Treatment includes phosphate binders, active vitamin D and calcimimetics.

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 Nephrology: CKD mineral bone disorder?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.