Gout and Pseudogout
Gout and pseudogout—calcium pyrophosphate deposition disease (CPPD)—are two types of crystalline arthropathies which are disease processes that cause sore joints because salt crystals have formed in the joint. The crystals irritate the joints and sometimes surrounding tendons, causing the body to release chemicals that make the joints swollen and red. In gout, the salt produced is monosodium urate, while in pseudogout it is calcium pyrophosphate.
Both of these conditions can affect joints outside the hand. In gout, the first joint affected is often the big toe. In pseudogout, the joints involved tend to be large joints such as the knee or wrist. Attacks can recur.