Gout and Pseudogout Flashcards
What is the pathophysiology of gout?
Gout is caused by monosodium urate crystal deposition in joints due to hyperuricemia, leading to an inflammatory response mediated by neutrophils.
What is the classic joint involvement in gout?
The first metatarsophalangeal (MTP) joint is most commonly affected, a condition known as podagra.
What are the risk factors for gout?
Hyperuricemia (due to purine metabolism disorders such as increased cell turnover from a hematological malignancy or chemotherapy) or chronic hemolysis, genetic enzyme disorder from Lesch-Nyhan (HGPRT deficiency) or PRPP synthetase overactivity seen in Von Gierke disease, kidney disease, diuretics, alcohol, or high-purine diet), male sex, obesity, hypertension, and metabolic syndrome.
What are the common triggers for gout attacks?
Triggers include alcohol, high-purine foods (red meat, seafood), dehydration, trauma, and certain medications (NSAIDs, thiazides, loop diuretics, or pyrazinamide).
What is pseudogout and its pathophysiology?
Pseudogout, or calcium pyrophosphate deposition disease (CPPD), is caused by the deposition of calcium pyrophosphate crystals in the joints.
What are the risk factors for pseudogout?
- Advanced age
- Osteoarthritis
- Hemochromatosis
- Hyperparathyroidism
- Hypothyroidism
- Hypomagnesemia
How does pseudogout appear on imaging?
Chondrocalcinosis (cartilage calcification) is visible on X-ray, commonly in the knee or wrist.
Which joints are most commonly affected in pseudogout?
The knee is the most commonly affected joint, but the wrist and shoulders can also be involved.
What symptoms are shared by both gout and pseudogout?
- Pain
- Redness
- Warmth
- Disability
- Both show an elevated leukocyte counts on joint fluid aspiration
What is the first step in diagnosing gout or pseudogout?
Arthrocentesis with synovial fluid analysis, including crystal examination, cell count, and Gram stain/culture to rule out septic arthritis. Both show an elevated leukocyte counts on joint fluid aspiration.
What are the microscopic characteristics of gout crystals?
Needle-shaped, negatively birefringent crystals under polarized light microscopy.
- Yellow when parallel
- Blue when perpendicular
What are the microscopic characteristics of pseudogout crystals?
Rhomboid-shaped, positively birefringent crystals under polarized light microscopy.
- Blue when parallel
- Yellow when perpendicular
How do you differentiate gout from pseudogout on joint aspiration?
- Gout shows needle-shaped, negatively birefringent crystals.
- Pseudogout shows rhomboid-shaped, positively birefringent crystals.
What is the treatment for an acute gout attack?
- First-line treatment includes NSAIDs (e.g., indomethacin or naproxen) or colchicine.
- Corticosteroids can be used in patients with contraindications to NSAIDs and colchicine (such as renal failure) .
What are the indications for urate-lowering therapy in gout?
- Frequent attacks (≥2 per year), tophi, chronic arthritis, urate nephropathy, or urolithiasis.
- The goal is to check uric acid levels less than 6 mg/dL.
What medications lower uric acid levels in chronic gout?
Allopurinol and febuxostat (xanthine oxidase inhibitors) or probenecid (uricosuric agent).
What is given for refractory gout?
IL-1 inhibitors (anakinra or canakinumab)
What is the treatment for an acute pseudogout attack?
NSAIDs (Indomethacin or naproxen) are first-line, followed by intra-articular corticosteroids or colchicine in some cases.
What systemic inflammatory conditions can mimic gout or pseudogout?
Septic arthritis, rheumatoid arthritis, and reactive arthritis can present similarly but require different treatments.
