Pseudogout is a form of arthritis triggered by deposits of calcium crystals (calcium pyrophosphate dihydrate) in the joints. It is also called calcium pyrophosphate deposition disease (CPPD). This disease can cause short-term or long-term swelling in joints, most often the knee, wrist, shoulder, ankle, or elbow.
As the name suggests, this condition can appear similar to gout, which is caused by another type of crystal – uric acid crystals – and commonly causes sudden pain and swelling in a single joint, usually in the foot. Pseudogout also can resemble osteoarthritis or rheumatoid arthritis.
In some cases, other medical conditions can make people more likely to develop pseudogout. These include:
An underactive thyroid (hypothyroidism)
A genetic disorder of iron overload (hemochromatosis)
Too much calcium (hypercalcemia) or too little magnesium (hypomagnesemia) in the blood.
Pseudogout also can be triggered by joint injury, such as joint surgery or a sprain, or the stress of a medical illness. Frequently, however, nothing can be identified that might have triggered the disease. Although age-related joint degeneration, prior joint damage or trauma, and these other medical conditions increase the likelihood of an attack of pseudogout, the reason some people develop this condition while others do not is unknown.
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