Most specific diagnostic finding in gout is -

The diagnosis of gout can be confirmed by the identification of urate crystals in the aspirate from a joint, bursa or tophus . In acute gout, the synol fluid may beturbid due to an elevated neutrophil count. In chronic gout, the appearance is more variable but occasionally the fluid appears white due to the presence of urate crystals. Between attacks, aspiration of an asymptomatic first MTP joint or knee may still reveal crystals. Ref Davidsons 23e p1015