A 58-year-old man presents with recurrent acute monoarthritis of the right knee. Synovial fluid analysis under polarised light microscopy shows weakly positively birefringent rhomboid-shaped crystals. Which of the following metabolic disorders is MOST classically associated with this condition?
- A Haemochromatosis ✓
- B Wilson disease
- C Homocystinuria
- D Alkaptonuria
Correct answer: A. Haemochromatosis
Explanation
Positively birefringent rhomboid crystals indicate calcium pyrophosphate deposition disease. Secondary CPPD is classically linked to four metabolic diseases: hyperparathyroidism, haemochromatosis, hypomagnesaemia and hypothyroidism, with haemochromatosis being the classic examination answer because iron deposition damages cartilage and promotes pyrophosphate release. Wilson disease causes copper overload with neurological and hepatic features but is not associated with chondrocalcinosis.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.