GOUT

Condition of inflammatory arthritis associated w/ hyperuricaemia.

Epidemiology:• More prevalent in developed countries.• Males : Females (10:1)

Etiology: 2 causes• Increased uric acid synthesis• Decreased uric acid excretion

[Hyperuricaemia: • Increased concentration of urea and uric acid in the blood• > 420 µmol / L (males)• > 360 µmol / L (females)]

Etiology (contd’.)

Increased uric acid synthesis (10% cases)• Uric acid is formed in the purine pathway. • Increased uric acid synthesis is observed in… ▪ Increased purine synthesis ▪ Action of phosphoribosyl pyrophosphatase enzyme ▪ G6PD deficiency (in Type-II DM) ▪ Carcinoma, Leukaemia, Polycythemia vera

Decreased uric acid excretion (90% cases)• Seen in HTN; 1° hyperparathyroidism; hypothyroidism;• Drugs (thiazide diuretics, low dose aspirin)• Decreased concentration of G6PD• Increased concentration of lactic acid (alcohol, starvation,

exercise)

Dx: Joint fluid microscopy (specific test but, risky and difficult) Blood tests (increased urate levels; > 600 µmol / L)

CLINICAL FEATURES : 4 Types1] Acute Gout:

• In middle-aged persons;• Sudden onset; swelling, redness, severe pain; occurs any time;• w/ out Tx, lasts for a week, then gradually person ‘recovers’

2] Chronic polyarticular gout:• Affects old people; mainly RF patients; those on diuretic Tx

3] Chronic Tophaceous Gout :• Tophi in skin, joints, ear lobes etc….• Results in ulceration• X-ray reveals bony cysts

4] Urate Renal stone formation

Tx :1] Anti-inflammatory agents(a) NSAIDs

• Naproxen (500 mg Q8H or Q12H; upto 750 mg)• Diclofenac (50 mg Q6H or Q8H; upto 75 – 100 mg)• Indomethacin (50 mg Q6H or Q8H; upto 75 – 100 mg)• Colchicine (500 mg Q6H or Q12H; upto 1gm)

(b) Corticosteroids (Methyl prednisolone via IM or IA)2] Serum urate reducers• Allopurinol (50 – 100 mg; upto 300 – 600 mg; can cause

skin rash)• Uricosuric agent (Probenecid 0.5 - 1 gm Q12H)• Allopurinol + Probenecid combination is preferred for

chronic tophaceous gout.3] Diet• Avoid alcohol, beer, shellfish and spinach (high purine

content).

THE END