CPPD secondary causes — SCE Rheumatology MCQ

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ModerateCrystal ArthropathiesCPPD secondary causesSCE Rheumatology

A 55-year-old man has recurrent CPP crystal arthritis with wrist and knee chondrocalcinosis and no established osteoarthritis. What is the most appropriate investigation?

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Correct answer: E — Serum calcium, magnesium, ferritin and parathyroid hormone

Serum calcium, magnesium, ferritin and parathyroid hormone is the single best answer because younger or recurrent CPPD should prompt assessment for metabolic associations. The stem is testing investigation selection, not isolated recall, so the relevant clinical pattern and risk context determine the answer. Septic arthritis is less suitable because it fits a different clinical pattern or a different treatment threshold; Reactive arthritis, Serum urate alone and Allopurinol during severe drug rash do not address the key discriminator in this vignette. Clinical pearl: in SCE-style rheumatology questions, autoantibodies, imaging and synovial fluid findings should be interpreted with the whole phenotype.

Reference: NICE NG219; BSR gout and hot swollen joint guidance; BNF