Immunology: rheumatoid arthritis serology: practice question

A Microbiology 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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Microbiology · Immunology: rheumatoid arthritis serology

Sample item

A 45-year-old woman has symmetrical swelling of the small joints of both hands with 90 minutes of morning stiffness for 4 months. Which serological test is most specific for her likely diagnosis and best predicts erosive disease?

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

The answer and the reasoning

A. Anti-cyclic citrullinated peptide antibody

Anti-CCP antibodies recognise citrullinated proteins and have specificity above 90% for rheumatoid arthritis, appearing years before disease and predicting erosions. IgM rheumatoid factor is more sensitive but less specific, as it is also raised in hepatitis C, endocarditis and other chronic infections. Antinuclear antibody and ASO are not diagnostic.

Option by option

  • A. Anti-cyclic citrullinated peptide antibody (correct)

    Anti-CCP combines high specificity with prognostic value for erosive disease.

  • B. Antinuclear antibody by immunofluorescence

    Antinuclear antibody is positive in lupus and other connective tissue disease and is not specific for this picture.

  • C. IgM rheumatoid factor

    Rheumatoid factor is positive in many infections and other autoimmune diseases, so it is less specific.

  • D. Antistreptolysin O titre

    ASO titre shows recent streptococcal infection and relates to rheumatic fever, not chronic symmetrical synovitis.

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 Microbiology questions

Questions about this Microbiology question

What is the answer to this Microbiology question?

The best answer is A, Anti-cyclic citrullinated peptide antibody. Anti-CCP antibodies recognise citrullinated proteins and have specificity above 90% for rheumatoid arthritis, appearing years before disease and predicting erosions.

Why is "Antinuclear antibody by immunofluorescence" not the answer?

Antinuclear antibody is positive in lupus and other connective tissue disease and is not specific for this picture.

Why is "IgM rheumatoid factor" not the answer?

Rheumatoid factor is positive in many infections and other autoimmune diseases, so it is less specific.

Why is "Antistreptolysin O titre" not the answer?

ASO titre shows recent streptococcal infection and relates to rheumatic fever, not chronic symmetrical synovitis.

What concept does this question test?

It tests Immunology: rheumatoid arthritis serology in Microbiology. IgM rheumatoid factor is more sensitive but less specific, as it is also raised in hepatitis C, endocarditis and other chronic infections. Antinuclear antibody and ASO are not diagnostic.

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 Immunology: rheumatoid arthritis serology?

Make a one-line identity card for each organism: shape and stain, defining test, toxin, disease and drug. Then use the flashcards and the other Microbiology 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.