Gout

Gout is an inflammatory arthritis caused by deposition of monosodium urate crystals in joints and soft tissues. Crystals form when serum urate reaches or exceeds its solubility threshold of approximately 6 mg/dL (360 µmol/L). The immune system recognizes the crystals as tissue injury; neutrophils and inflammatory mediators, including interleukin-1β, then produce intense pain, edema, erythema, and warmth. Hyperuricemia usually reflects reduced renal excretion rather than excessive production alone. Chronic kidney disease, dehydration, obesity, metabolic syndrome, family history, and diuretic therapy with a thiazide or loop diuretic increase risk. Frequent alcohol intake—especially beer—and high-purine foods such as organ meats, some shellfish, and large amounts of red meat can further raise urate. The metatarsophalangeal joint of the great toe is the classic site, called podagra. Repeated attacks can produce tophi, persistent joint damage, or uric acid kidney stones. A painful flare is only the visible part of the problem; sustained urate reduction is what prevents new crystals from forming.