Crystal Arthropathy

Let's talk about a common problem seen on Internal Medicine - Crystal Arthropathy

                           

Gout - Negatively birefringement crystals

CPPD - Weakly positive rhomboid crystals

CPPD 

• 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

                 

GOUT

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