Bone tumours: Bence Jones protein in myeloma: 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 · Bone tumours: Bence Jones protein in myeloma

Sample item

A 62-year-old has back pain, anaemia, renal impairment and punched-out skull lesions. A urine dipstick is negative for protein, but the sulfosalicylic acid test is strongly positive. Which protein is responsible?

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

The answer and the reasoning

D. Monoclonal free light chains

Dipsticks detect mainly albumin, whereas free light chains (Bence Jones protein) are missed but precipitate with sulfosalicylic acid. Urine and serum electrophoresis with free light chain assay confirm the monoclonal protein of multiple myeloma.

Option by option

  • A. Tamm-Horsfall mucoprotein

    Tamm-Horsfall mucoprotein forms casts and is not the monoclonal protein of myeloma.

  • B. Myoglobin

    Myoglobin would give a haem-positive dipstick and does not explain lytic skull lesions.

  • C. Albumin

    Albumin would make the dipstick positive.

  • D. Monoclonal free light chains (correct)

    Correct. Free light chains are missed by dipstick but detected by acid precipitation.

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, Monoclonal free light chains. Dipsticks detect mainly albumin, whereas free light chains (Bence Jones protein) are missed but precipitate with sulfosalicylic acid.

Why is "Tamm-Horsfall mucoprotein" not the answer?

Tamm-Horsfall mucoprotein forms casts and is not the monoclonal protein of myeloma.

Why is "Myoglobin" not the answer?

Myoglobin would give a haem-positive dipstick and does not explain lytic skull lesions.

Why is "Albumin" not the answer?

Albumin would make the dipstick positive.

What concept does this question test?

It tests Bone tumours: Bence Jones protein in myeloma in Orthopaedics. Urine and serum electrophoresis with free light chain assay confirm the monoclonal protein of multiple myeloma.

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 Bone tumours: Bence Jones protein in myeloma?

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.