Crystal-induced Arthritis (Gout & Pseudogout) Flashcards
What is Gout?
Deposition of monosodium urate (MSU) crystals leading to a crystal-induced arthropathy.
Hyperuricemia (> 6.8 mg/dL)
Population affected in Gout?
more common in Men and Elderly
State the crystal morphology of Gout
needle shaped (monoclinic)
What happens in uncontrolled gout?
Gouty attack (Podagra) = acute gouty arthritis > Repeated gouty attacks > chronic gout > permanent deposits of urate crystals > Tophaceous gout
What causes gout?
1) Overproduction of uric acid
- increased consumption (red meat, seafood)
- increased production of purines (High frutose corn syrup beverages)
2) Undersecretion of uric acid > dehydration
3) Medications:
- thiazide diuretics
- loop diuretics
- cyclosporine
- low-dose aspirin
- pyrazinamide
What is the gold-standard test for Gout?
Synovial fluid analysis > joint fluid aspiration and crystal analysis is gold-standard
- Negatively birefringent needle-shaped crystals under polarized light
- Yellow under parallel light and blue under perpendicular light
What is State the crystal morphology of Pseudogout ?
A metabolic arthropathy due to deposition of calcium pyrophosphate dihydrate (CPPD) in connective tissue
Population affected in Pseudogout?
Male=Female, Age above 50 years old
State the crystal morphology of Pseudogout
Triclinic (rhomboid) or monoclinic (needle)
What causes Pseudogout?
1) Aging and/or genetic factors may result in increased adenosine triphosphate breakdown producing inorganic pyrophosphate
2) Inorganic pyrophosphate binds with calcium producing CPP
3) CPP then deposits in cartilage and synovial fluid leading to a synovitis
To diagnose Pseudogout
Arthrocentesis & crystal analysis
- Positively birefringent rhomboid crystals under polarized light
- Blue under parallel light and yellow under perpendicular light
How to differentiate between gout & pseudogout?
via polarizing light microscopy
What radiographic findings are seen in pseudogout?
Chondrocalcinosis
What are the Routine studies of SF?
1) Gross appearance
2) WBC count and differential count
3) Culture & Gram stain
4) Crystal analysis
