Tophus due to gout. Illustration of the internal anatomy of a foot, showing a tophus (swelling) due to gout. At lower left, the tophus is seen at the base of the big toe. The area is red and inflamed and tender. Gout is a disease in which a defect in uric acid metabolism causes an excess of the acid and its salts (sodium urate) to accumulate in the blood and in the joints. Crystals of uric acid collect in joint capsules as tophi, causing an acute inflammation. The large toe is commonly affected. Gout is associated with overeating and overdrinking. Treatment involves the use of anti- inflammatory drugs, and abstention from rich foods and excessive alcohol.