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Gout: Causes, Risk Factors, and Why It's Not Contagious

Gout: An Inflammatory Arthritis from Urate Crystals

Gout is a crystal deposition disease caused by monosodium urate (MSU) crystals precipitating in joints and tissues due to chronic hyperuricemia (serum urate >6.8 mg/dL, the saturation point). It is not contagious—no infectious agent is transmitted person-to-person.

Pathophysiology

  • Uric acid = end product of purine metabolism (endogenous + dietary).
  • Hyperuricemia: Overproduction (10%) or, more commonly, underexcretion (90%) by kidneys.
  • MSU crystals form in cool, avascular tissues (joints, especially 1st MTP).
  • Crystals phagocytosed by neutrophils → NLRP3 inflammasome activation → IL-1β release → intense inflammation.

Risk Factors

ModifiableNon-Modifiable
Diet: High purine (red meat, organ meat, shellfish, anchovies, sardines)Genetics: SLC2A9, ABCG2 variants (urate transport); family history
Alcohol: Beer > spirits > wine (guanosine, ethanol → lactate competes with urate excretion)Sex: Male > female (estrogen promotes uricosuria); postmenopausal women catch up
Sugar-sweetened beverages (fructose → urate synthesis)Age: Incidence rises with age
Obesity / Metabolic syndrome (insulin resistance ↓ urate excretion)CKD: Reduced renal clearance
Diuretics (thiazide, loop), low-dose aspirin, cyclosporineEthnicity: Higher in Pacific Islanders, Māori, Black populations
Lead exposure (saturnine gout)

Clinical Stages

  1. Asymptomatic hyperuricemia: No treatment unless very high (>12 mg/dL) or high-risk (transplant, chemo).
  2. Acute gout flare: Sudden, excruciating pain, swelling, erythema, warmth (1st MTP = podagra). Self-limited 3–14 days.
  3. Intercritical gout: Asymptomatic between flares; crystals persist.
  4. Chronic tophaceous gout: Tophi (chalky deposits) in ears, olecranon, Achilles, joints → erosions, deformity.

Management

Acute Flare

  • NSAIDs (indomethacin, naproxen), colchicine (low-dose 0.6 mg stat then 0.3 mg q12h), glucocorticoids (oral, IA, IM). Start ASAP.

Urte-Lowering Therapy (ULT) — Indicated If:

  • ≥2 flares/year, tophi, CKD stage ≥3, urolithiasis, radiographic damage.
  • Target serum urate <6 mg/dL (<5 mg/dL if tophi).
  • First-line: Allopurinol (start low, titrate; HLA-B*58:01 screen in high-risk populations). Febuxostat if allopurinol intolerant (CV caution).
  • Prophylaxis (colchicine 0.6 mg daily/ BID) during ULT initiation (6 months) to prevent flares.

Lifestyle

  • DASH/Mediterranean diet, limit alcohol (esp. beer), avoid fructose, weight loss, hydration.

Gout is a chronic metabolic disease, not an infectious one. It is eminently treatable with modern ULT.

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