Systemic (Rheumatic)
Gout
통풍
Metabolic disease where monosodium urate (MSU) crystals deposit in joints causing acute/chronic arthritis
- How common
- 3–6% of adult males
- Typical age
- Men >40, postmenopausal women
What is it?
Hyperuricemia exceeds saturation, precipitating MSU crystals that trigger acute neutrophilic inflammation in joints.
Commonly affected: 1st MTP (podagra, 50%) most common; ankle, knee, wrist, finger
How it develops
- HyperuricemiaOverproduction or underexcretion of urate
- MSU Crystal FormationNeedle-shaped crystals in synovial fluid/cartilage
- NLRP3 Inflammasome ActivationIL-1β release recruits neutrophils
- Acute AttackSevere pain, redness, warmth, swelling (peaks in 24 hours)
Symptoms
- Podagra (1st MTP)Acute 1st MTP severe pain, erythema, swelling
- Acute nocturnal attackOften wakes patient at night; peaks within 24 hours
- Erythema/warmthMay mimic cellulitis
- Chronic arthropathyJoint destruction/deformity after recurrent attacks
- Tophi (chronic)Painless urate nodules on ear, elbow, fingers
How it is examined
- MSU crystals on aspirationNegatively birefringent needle-shaped crystals on polarized microscopy — gold standard
- Serum uric acid >6.8 mg/dLHyperuricemia; may be normal during acute attack
- Tophi palpationNodules over helix of ear or olecranon bursa
- US double contour signCharacteristic US finding of urate on cartilage surface
Imaging
X-ray shows punched-out erosions with overhanging edges; acute phase shows only soft tissue swelling.
- Punched-out erosions
- Overhanging edges (rat-bite)
- Joint space preserved (early)
- Soft tissue tophi
US useful — shows double contour sign and tophi; MRI evaluates tophi and soft tissue.
- Double contour sign on US
- Urate deposits (US hyperechoic)
- Tophi (T1/T2 low signal)
- Synovitis
Non-surgical care
- Acute attack (NSAIDs/colchicine/steroids)Indomethacin, naproxen, colchicine 1.2→0.6 mg, oral/IA steroids
- Urate-lowering (allopurinol)First-line long-term prevention — target uric acid <6 mg/dL
- Febuxostat/uricosuricsFor allopurinol intolerance/failure; probenecid (uricosuric)
- Lifestyle (diet/alcohol/weight)Limit purines (organ meat, shellfish, beer), avoid alcohol, weight loss, hydration
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
Functional loss from large tophi, abscess, fistula
Procedures that may be discussed
- Tophi excision
- Joint lavage/synovectomy
- Arthrodesis (severe destruction)
Outlook
Long-term remission achievable with urate-lowering therapy; untreated risks joint destruction, stones, renal failure.