Gout, a type of inflammatory arthritis caused by a buildup of uric acid (urate) in the body, affects 5.1% of U.S. adults (over 12 million), including 10% of those aged 65 or older. Urate is produced by the body when breaking down compounds called purines and normally dissolves in the blood, but when levels are high, they can precipitate out as monosodium urate crystals which can deposit in the joints.