Calcium Pyrophosphate Deposition (Pseudogout)

Related Subjects: |Calcium Physiology | Rheumatoid arthritis | Systemic Sclerosis (Scleroderma) | RA vs OA | Acute and Chronic Gout | Calcium Pyrophosphate Deposition (Pseudogout)

Every effort should be taken to aspirate involved joints to exclude a septic joint where diagnosis not certain. Involve on-site orthopaedic teams/radiology for ultrasound-guided aspiration if necessary. Record colour, viscosity and turbidity. Microscopy for cell count, differential and Gram stain (Microbiology); polarising microscopy for crystals (Histopathology lab) Culture.

About

• Pseudogout syndrome first described by Kohn and colleagues in 1962
• A cause of an acute painful joint often in older patients
• Accumulation of calcium pyrophosphate dihydrate crystals or CPPD crystals in connective tissues or the joint cartilages.
• Affects cartilage of knee (hyaline cartilage and menisci), then wrist (triangular fibrocartilage) and pelvis (symphysis pubis).

Aetiology

• Deposition of Calcium Pyrophosphate crystals in articular cartilage and periarticular tissue
• Increased ATP breakdown which leads to increased inorganic pyrophosphate in the joints results from aging, genetic factors, or both.
• CPDD is a common condition that occurs with aging in all races

Associations

• Haemochromatosis
• Hypothyroidism
• Hyperparathyroidism
• Haemophilia
• Wilsons disease
• Bartter syndrome
• Hypomagnesaemia
• Ochronosis
• Amyloidosis

Chondrocalcinosis: Calcification of the cartilage

Clinical

• Acutely inflamed tender joint due to cartilage calcification
• Large joints are more commonly affected
• Attacks are characterized by hot, tender, red and swollen joints
• Middle aged or elderly.
• Hips, Knee or wrist most often affected.
• Can mimic gout/sepsis. Previous attacks likely.
• Can persist for several months In young people it may be associated with haemochromatosis, hyperparathyroidism, Wilson’s disease or alkaptonuria (excess homogentisic acid polymerizes to produce a black/brown product deposited in cartilage and other tissues).

Investigations

• FBC and diff, ESR and CRP. Raised ESR and CRP
• U&E, Calcium: exclude primary hyperparathyroidism if high calcium
• Check Ferritin and exclude haemocromatosis
• Blood cultures x3.
• X-ray: Chondrocalcinosis is linear calcification in hyaline cartilage and/or fibrocartilage.
• Joint Aspirate if available: Polarising light: Calcium pyrophosphate crystals are smaller, rhomboid in shape and usually less numerous than urate crystals; they have weak intensity and positive birefringence. Gout and pseudogout may co-exist. WCC 10,000-50,000 WBC/microlitre

Differential

• Gout vs Pseudogout: Pseudogout attacks may take longer to reach peak intensity and may persist for up to 3 months despite therapy. Crystal and radiology can help. In pseudogout Large joints are more commonly affected and the attacks are characterized by the cardinal signs of inflammation which may involve one or several hot, tender, red and swollen joints.
• Gout and pseudogout may also coexist in a single inflammatory effusion, as 20% of patients with CPPD will have hyperuricaemia and a quarter of these will develop gout at some stage

Management

• Unlike gout, the treatment of CPPD-related arthropathies is often difficult, partly due to patient characteristics, diagnostic uncertainty and the lack of any effective agent to decrease crystal load
• Acute attack (NSAIDs/Colchicine/Steroid)
  • Admit if severe and septic arthritis suspected. bed rest, elevate the limb and give analgesia. Less acute and rapid then acute gout and can persist longer.
  • If joint sepsis considered then Joint aspiration to exclude infection and confirm diagnosis.
  • NSAIDs: first line. Avoided if Elderly/CKD. Consider short term PPI. Consider Ibuprofen and keep course short if possible.
  • Colchicine tends to be used as 0.5 mg BD for several days or longer
  • Prednisolone PO 10-15 mg for up to a week. Occasionally higher doses sometimes needed.
• Chronic inflammatory arthritis
  • Hydroxychloroquine
  • Methotrexate
• Prophylaxis
  • Colchicine: against acute attacks of pseudogout
  • NSAIDs (+ PPI)

References

• Treatment and management of pseudogout: insights for the clinician
• Patient information leaflet