A 65-year-old man presents with large joint mono/oligoarthritis, calcium pyrophosphate crystals (weakly positive birefringent rhomboid crystals) in synovial fluid, chondrocalcinosis on knee X-ray, and mild hypomagnesemia. Which underlying condition should be screened for?
- A Hyperuricemia
- B Hemochromatosis ✓
- C Primary hyperaldosteronism
- D Reactive arthritis
Explanation
Calcium pyrophosphate deposition (CPPD) disease/pseudogout is associated with several metabolic conditions: hemochromatosis, hyperparathyroidism, hypomagnesemia, hypophosphatasia, and hypothyroidism. Hemochromatosis causes CPPD through iron deposition affecting pyrophosphate metabolism in cartilage. Iron deposition also causes a distinctive arthropathy of the 2nd and 3rd MCPJs with 'hook osteophytes'. CPPD in young patients (<55 years) or those with multiple joint involvement should always prompt screening for these secondary causes. Hyperuricemia causes monosodium urate (gout), not CPPD.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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