Crystal arthropathies Flashcards
What are the crystal arthropathies?
- Gout
- Psuedogout (Calcium pyrophosphate deposition (CPPD))
Describe gout?
- Acute monoarthropathy with severe joint inflammation (MTP of big toe)
- Monosodium urate crystals in synovial joints
- Raised plasma urate
- Can be precipitated by surgery, starvation, infection, diuretics
What are the differentials for gout?
- Exclude septic arthritis (acute monoarthropathy)
- Reactive arthritis, haemarthrosis, CPPD
Describe the risk factors for gout?
- Increasing age
- Reduced urate excretion
- Elderly, men, post-menopausal females, hypertension
- Diuretics, anti-HTN, aspirin
- Excess urate production
- Alcohol, red meat, seafood, sweeteners
- Alcohol, warfarin, cytotoxics
- Myelo- and lymphoproliferate, psoriasis
Describe the pathophysiology of gout?
- Imbalance of uric acid synthesis and elimination
- Removed via kidneys (2/3) and gut (1/3)
- Xanthine oxidase plays important role in producing uric acid
Clinical features of gout?
- Rapid-onset, acute monoarthritis
- 1st MTP joint in 50% of cases
- Also ankle, midfoot, knee, small hand joints, wrist and elbow
- Severe pain and tenderness
- Swelling with overlying red, shiny skin
- Tophi form from cystal deposits
Screening in gout?
- Gout is a risk factor for CV and renal disease mortality
- Screen for CKD, hypertension, dyslipidaemia and diabetes
Describe the investigations into gout?
- Polarized light microscopy of synovial fluid
- Negatively birefringent urate cystals
- Serum urate (raised)
- X-rays
- Soft tissue swelling
- Punched out erosions in bone
What are the different causes of hyperuricaemia and gout?
What drugs can cause hyperuricaemia and gout?
- Diuretics
- Aspirin
- Ciclosporin
- Pyrazinamide
Describe the treatment of acute gout?
- NSAIDs + PPI
- Colchicine (effective but slower to work)
- Corticosteroids
- Rest + elevate joint + ice packs
What is problematic in the treatment of acute gout?
NSAIDs + colchicine are problematic in renal impairment
Describe some prevention measures for acute gout?
- Lose weight
- Avoid fasts, alcohol excess and purine-rich meats
- If symptomatic or >1 attack in 12 months
- Allopurinol
- If allopurinol is CI:
- Febuxostat
Indications for the use of urate-lowering drugs?
- Tophi
- Recurrent attacks
- Evidence of bone/joint damage
- Renal impairment/calculi
What is the first line urate lowering therapy?
Allopurinol
Describe Allopurinol?
- Xanthine oxidase inhibitor
- Reduced conversion of hypoxanthine/xanthine to uric acid
- Acute flares normally occur on intiation of Allopurinol
- SEs: Rash, fever, reduced WCC
Describe Febuxostat?
- Xanthine oxidase inhibitor
- 2nd line for urate-lowering therapy
- SE: increased LFTs
- Hepatic metabolism
- More effective than Allopurinol
What is pictured here?
Acute monoarthritis in gout
What is pictured here?
Ulcerated tophi in gout
What is pictured here?
- Gout
- Needle-shaped monosodium urate crystals
- Negative birefringence under polarized light
What is pictured here?
- Psuedogout
- Rhomboid-shapred CPPD crystals
- Positive birefringence in polarized light
Describe Acute CPPD crystal arthritis?
- Acute monoarthropathy
- Deposition of calcium pyrophosphate dihydrate cystals
- Usually of larger joints in the elderly
- Can be provoked by illness, surgery or trauma
Describe Chronic CPPD?
- Inflammatory symmetrical polyarteritis and synovitis
- Can be mistaken for RA
What are the risk factors for CPPD?
- Age
- Osteoarthritis
- Hyperparathyroidism
- Haemachromatosis, wilson’s
- Hypophosphataemia/hypomagnesaemia
