Arthritis due to deposition of monosodium urate monohydrate crystals in previously normal tissues causing acute inflammation and eventual tissue damage. The four types of gout are:

Asymptomatic, hyperuricaemia, acute gout, and intercritical gout & chronic tophaceous gout.

Classification

The condition can be classified into 1˚ or 2˚ gout depending on the cause of hyperuricaemia:

1. Primary gout occurs mainly in men age 30-60 years presenting with acute attacks.
2. Secondary gout normally due to chronic diuretic Rx. Older M & F, assoc with OA.

Pathogenesis

It affects both upper and lower limbs with acute attacks. Less often it presents with painful, tophaceous deposits (± discharge) in Heberden’s and Bouchard’s nodes.

1. Most pts with hyperuricaemia never → gout and gouty pts may be normouricaemic.
2. Patients can be over-excreters of uric acid, normo-excreters or under-excreters.
3. Most cases of primary gout are due to undersecretion. <10% due to overproduction.

Epidemiology

1. Fairly common.
2. 9M:1F

Risk factors

1. Male sex
2. Meat & seafood
3. Alcohol (>10g/d)
4. Diuretics
5. Obesity
6. Hypertension
7. IHD
8. Diabetes mellitus
9. CRF
10. High triglycerides
11. Malignancy

Presentation

1. Acutely inflamed joint typically over 6-24hr period
2. 50% of all attacks & 70% 1st attacks affect 1st MTPJ (“podagra”).
3. Other sites often affected are: Knee, midtarsal joints, wrists, ankles, small hand joints, elbows
4. Chronic tophaceous gout – large irregular firm white-yellow nodules mainly around extensor surfaces of fingers, hands, forearms, elbows, achilles tendons and ear.

Investigations

Urine: 24hr renal uric acid secretion

Blood: FBC, uric acid (poor sensitivity & specificity), CMP, BSL, lipids

Joint aspirate: Gram stain, WCC, microscopy – monosodium urate (MSU) crystals (negatively birefringent) or tophi for gout.

Imaging: chronic gout – punched out lesions, sclerosis and tophi may be seen.

Management

Supportive: Ice pack, rest, regular paracetamol±codeine,

Manage risk factors: ↓hyperuricaemic drugs (thiazides and loop diuretics, low dose aspirin < 1g/day, pyrazinamide, ethambutol, nicotinic acid, ciclosporin), lose wt, ↓meat/seafood, ↓EtOH, treat HT/renal impairment/hyperlipidaemia/vascular disease.

Anti-inflammatories:

1. NSAIDs – Avoid aspirin (continue if on IHD antiplatelet dose). Indomethacin or diclofenac 50mg tds. Risk of GIT SE esp if high EtOH intake. OR
2. Colchicine – 0.5mg/hr until better, max 6mg (3mg if renal/liver disease), or diarrhoea.
3. Steroids – 2nd line. Prednisolone 10mg bd x 5d, then taper over 2wks. Injs may help.

Uricosuric drugs:

1. Probenecid, losartan.

Prophylaxis: If regular attacks. Delay until 2-3wks after acute attack resolves.

1. Co-prescribe colchicine or NSAID to prevent gout whilst initiating Rx
2. Allopurinol 300mg OD – 1st choice esp if impaired renal function or calculi present.
3. Sulfinpyrazone – alternative to allopurinol or as adjunct in resistant cases. CI: if RF
4. Colchicine – 0.5mg bd
5. Low dose corticosteroids and NSAIDs have also been used

Complications

1. Recurrent painful episodes
2. Renal disease: calculi (10-25%, urate or oxalate), chronic urate nephropathy.
3. Severe degenerative arthritis
4. Secondary infections
5. Carpal tunnel syndrome (rare)
6. Nerve or spinal cord impingement