Epidemiology

The aetiopathogenesis of gout is initiated by urate overproduction and uric acid under-excretion, leading to hyperuricaemia. Foods such as seafood, red meat, beer, and sugar-sweetened beverages contribute to overproduction. Under-excretion is mediated by renal and gut uric acid transporters such as SLC2A9, ABCG2, and URAT1. In hyperurcaemia, there is formation of monosodium urate (MSU) crystals in joints, with acute gouty arthritis mediated by the innate immune system occurring in response to these crystals. Factors such as urate concentration, proteins present in synovial fluid, temperature, and pH control crystal nucleation and growth. Activation of the inflammasome by MSU crystals and production of interleukin-1ß‎ is central to acute gouty arthritis. Advanced gout occurs when there is persistent gouty arthritis and tophus with the tophus being an organized immune tissue response to MSU crystals that involves both innate and adaptive immune cells. Progression through the gout checkpoints (hyperuricaemia, MSU crystal formation, and immune response) is governed by inherited genetic variants, lifetime environmental exposures, and their interaction.