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Haemochromatosis CPPD Mechanism — RACP Adult Medicine MCQ

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ModerateRheumatologyHaemochromatosis CPPD MechanismRACP Adult Medicine

A 55-year-old woman presents with recurrent attacks of monoarthritis. Between attacks she is asymptomatic. Joint aspiration during an attack shows positively birefringent rhomboidal crystals. She is found to have haemochromatosis. What is the metabolic link between haemochromatosis and CPPD disease?

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Correct answer: E — There is no link – coincidental

Haemochromatosis predisposes to CPPD disease through iron deposition in articular cartilage, which inhibits pyrophosphatase enzymes responsible for clearing inorganic pyrophosphate. The resulting pyrophosphate accumulation leads to calcium pyrophosphate crystal deposition and chondrocalcinosis. This explains why the 2nd and 3rd MCPJs (characteristic of haemochromatosis arthropathy) and large joints (knees, wrists) are commonly affected. Importantly, CPPD arthropathy in haemochromatosis does NOT improve with iron depletion – the cartilage damage and crystal deposition are largely irreversible.

Reference: eTG – 2025 – Rheumatology; EASL – 2010 – Haemochromatosis