|
Snapshot
  • A 55-year-old woman presents to the emergency department with acute pain in the left proximal interphalangeal (PIP) joint of the second digit. She reports that the pain is excruciating and has happened once a few years ago but self-resolved over the course of 2 weeks. She states that she recently increased her alcohol and red meat consumption and was recently started on hydrochlorothiazide. On physical exam the PIP joint is swollen, erythematous, warm, and tender to palpation. Preparations are made for an arthrocentesis to be performed. 
Introduction
  • Clinical definition
    • deposition of monosodium urate crystals leading to a crystal-induced arthropathy
  • Epidemiology
    • demographics
      • more common in men and the elderly
    • risk factors
      • conditions that increase serum urate levels (hyperuricemia)
  • Etiology
    • hyperuricemia 
      • defined as a serum urate level > 6.8 mg/dL
      • causes of hyperuricemia include
        • dietary habits
          • alcohol
          • red meat
          • seafood
        • medications
          • thiazide diuretics
          • loop diuretics
          • allopurinol
          • cyclosporine
          • low-dose aspirin
          • pyrazinamide
        • disorders of urate overproduction
          • hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency
            • also known as Lesch-Nyhan syndrome
          • type I glycogen storage disease (Von Gierke disease)
          • tumor lysis syndrome
  • Pathogenesis
    • purine catabolism results in uric acid production
      • factors that influence serum uric acid level include
        • purine intake
        • purine synthesis
        • uric acid excretion by the kidneys and gut
    • conditions that increase the serum uric acid concentration increases the risk of crystal formation
      • deposition of uric acid crystals lead to an inflammatory response
        • resulting in a gout flare
  • Prognosis
    • acute attacks typically self-resolve
    • patients have an increased risk of recurrence
    • advanced gout and tophi may result without proper treatment
Presentation
  • Symptoms
    • acute gout
      • extreme pain of the affected joint (e.g., foot or ankle)
    • chronic tophaceous gout
      • stiff or swollen joint
      • deformity of the affected joint (e.g., nodules)
  • Physical exam
    • acute gout
      • typically mono-articular
        • e.g., involvement of the first metatarsophalangeal joint (podagra)
      • sudden onset of joint
        • tenderness
        • erythema and warmth
        • swelling
    • chronic tophaceous gout
      • subcutaneous nodules
      • typically non-tender
      • overlying skin can be taut
      • abnormal color
        • white or yellow deposits
Studies
  • Labs
    • hyperuricemia (> 6.8 mg/dL)
      • not sufficient for the diagnosis
      • the level may be lower during an attack
  • Synovial fluid analysis  
    • joint fluid aspiration and crystal analysis is the gold-standard
      • negatively birefringent needle-shaped crystals under polarized light 
        • yellow under parallel light and blue under perpendicular light
  • Making the diagnosis
    • demonstrating monosodium urate crystals in an affected joint via polarizing light microscopy
      • when this is not possible, the diagnosis can be clinically made
Differential
  • Septic arthritis 
    • a highly important differential diagnosis to exclude since this changes management 
    • distinguishing factors
      • a synovial fluid analysis will demonstrate
        • no crystals
        • > 50,000 cells/mcL
        • Gram stain may be positive
  • Pseudogout 
    • distinguishing factors
      • caused by deposition of calcium pyrophosphate crystals
      • crystal analysis will demonstrate weakly positive birefringent rhomboid crystals under polarized light
        • blue under parallel light
Treatment
  • Management approach
    • acute attacks can be managed with nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, or colchicine
      • acute gout attacks typically self-resolve in 1-2 weeks; however, treatment will hasten recovery
      • choice of treatment is dependent on certain patient factors (e.g., comorbidities, gout history, attack characteristics, availability, and cost)
    • preventing future attacks are managed by urate-lowering therapy
  • Conservative
    • lifestyle modification
      • indication
        • a preventative measure for patients with gout
      • examples
        • decrease alcohol, red meat, and seafood consumption
        • weight loss
        • discontinuing or modifying medication (e.g., changing their loop diuretic)
  • Medical  
    • medical management of acute attacks
      • NSAIDs 
        • indication
          • monotherapy agent for acute gout attacks
      • colchicine
        • indication
          • monotherapy agent for acute gout attacks
      • corticosteroids 
        • indication
          • monotherapy agent for acute gout attacks
    • medical management for preventing a future attack
      • urate-lowering therapy
        • indication
          • to prevent future attacks
        • medications
          • xanthine oxidase inhibitors (first-line)
            • e.g., allopurinol and febuxostat
          • uricosuric agents (second-line)
            • e.g., probenecid 
Complications
  • Recurrent flares
  • Tophi
  • Chronic gouty arthritis
  • Erosion or destruction of the joint
 

Please rate topic.

Average 5.0 of 3 Ratings

Questions (8)
EVIDENCE & REFERENCES (5)
Topic COMMENTS (11)
Private Note