questions 2

Gout

Topic updated on 11/06/17 9:27am

Snapshot
  • A 46-year-old man presents to the emergency department due to severe pain of the first metatarsophalangeal (MTP) joint of acute onset. He describes the pain as 10/10 and sharp. Medical history is significant for obesity and hypertension and was recently started on furosemide. Social history is notable for alcohol use disorder managed with naltrexone. He reports to recently increasing his alcohol intake due to environmental stresses. On physical exam, the right first MTP joint appears erythematous, swollen, and is warm. Preparations are made to perform an arthrocentesis.
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 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 
    • this is 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 



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Qbank (2 Questions)

TAG
(M1.MK.10) A 60-year-old man has had intermittent pain in his right great toe for the past 2 years. Joint aspiration and crystal analysis shows thin, tapered, needle shaped intracellular crystals that are strongly negatively birefringent. Radiographs are shown in Figure A. What is the most likely cause of this condition? Topic Review Topic
FIGURES: A          

1. Monosodium urate crystal deposition
2. Calcium pyrophosphate deposition
3. Uric acid crystal deposition
4. Tuberculosis
5. Rheumatoid arthritis

PREFERRED RESPONSE ▶
TAG
(M1.MK.4666) A 75-year-old woman presents with worsening "nodules" on her body. She describes several years of intermittent, severe joint pain, which she ascribed to arthritis with "old age." Her hand is shown in Figure A. Which of the following interventions is best for long-term treatment of this condition? Topic Review Topic
FIGURES: A          

1. Probenecid
2. Colchicine
3. Allopurinol
4. Non-steroidal anti-inflammatory agents
5. Thiazides

PREFERRED RESPONSE ▶


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