Monday, March 16, 2015

Crystal Arthropathy

Let's talk about a common problem seen on Internal Medicine - Crystal Arthropathy
Gout - Negatively birefringement crystals
CPPD - Weakly positive rhomboid crystals

  • Most are idiopathic; inflammation due to calcium deposit in the joint
  • Remember 3 Hs 
    • Hemochromatosis
    • Hyperparathyroidism
    • Hypomagnasemia (Gittelmans, Bartters)
  • Some more H's - hypothyroidism, hypophosphatemia, hypomagnesemia
  • Hemochromatosis - 2nd + 3rd MCP/PIP
  • Suspect CPPD when the presentation sounds like OA in odd locations (eg MCP) with chrondrocalcinosis
  • Basic Calcium Phosphate (BCP) - Milwaukee shoulder - destructive, acute, older females, associated with prior trauma
  • Arthrocentesis:  WBC 2000 - 10000. PMNS greater than 50%.
  • Acute treatment: Joint aspiration/steroid injection is first line
    • NSAID is second line
    • Colchicine, steroids (systemic or intra-articular) also used
    • Prophylaxis with colchicine if more than 2 attacks/year


Secondary Causes
  • PRV, hemolysis, TLS
  • Diet - beer, red meat, seafood
  • Increased meat, seafood, alcohol
  • Male, obesity
  • HTN
  • CKD
  • Leukemia/Lymphoma
  • Drugs: Cyclosporine, salicylates, HCTZ
Non-Pharmacologic Treatment
  • Lose weight
  • Change diet - increase protein
  • lower alcohol
  • Remove diuretic, change to losartan
Pharmacologic Therapy
  • Start ASAP
  • Treat with NSAIDs: 
    • eg Naproxen 500 mg bid or indeomethacin 50 mg tid. 
    • Duration: until 1-2 days after symptoms resolve (usually 5-7 days). 
    • Avoid ASA - will make it worse.
  • If contra-indicated, treat with colchicine 1.5 mg q8H x3, then taper until resolution. Colchicine is initiated in acute attacks only.
    • Only start this if symptoms are less than 48 hours
    • Don't use IV colchicine.
  • If contra-indicated, treat with oral, intra-articular, or IV glucocorticoids. 
    • Use only steroids for CKD and ESRD.
    • Intra-articular injection for those with 1-2 affected joints who can't take above medications.
    • Prednisone 30-50 mg daily over 7-10 days.
    • Intravenous - if all the above is contra-indicated; 20 mg methylprednisone IV.
  • Prophylaxis with urate lowering therapy in these people. 
    • 2 or more attacks/year
    • Tophi
    • Kidney stones
    • Radiographic changes
    • Urinary uric acid greater than 1100 mg/day
  • Which agent, how much?
    • Don't start during acute attack
    • Even when stable, start with overlap with NSAID/colchicine. Preferably Colchicine - continue for 6 months after normal urate is achieved.
    • Titrate to urate level less than 357 umol
    • Renal dose adjustment
    • Start with allopurinol; if intolerant, move on to febuxostat
    • Don't use these two agents when the patient is also on azathioprine
      • In this case, use probenacid instead (causes stones - make sure to hydrate)
    • If very severe, treat with IV pegloticase Q2 weeks

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