Pseudogout is a type of arthritis that, as the name implies, can cause symptoms similar to gout, but which are a reaction to a different type of crystal deposit. This type of arthritis may be one of the most misunderstood forms, and is often mistaken for gout and other conditions, including RA. Proper diagnosis is important because untreated pseudogout may lead to a severe form of joint degeneration and ongoing inflammation, resulting in chronic disability.
Pseudogout develops when deposits of calcium pyrophosphate crystals accumulate in a joint. Initially, crystals deposit in the cartilage and can cause damage. They also can cause a reaction with inflammation that leads to joint pain and swelling. This can cause more chronic arthritis that mimics osteoarthritis or RA. Knees are most often involved, but wrists, shoulders, ankles, elbows, and hands can be affected. Ultimately, a patient with pseudogout could be incapacitated for days or weeks.
Anyone can develop pseudogout, and the risk greatly increases with age. According to patient fact-sheet writer H. Ralph Schumacher, MD, “about 3% of people in their sixties, and as many as 50% of people in their nineties, show evidence of pseudogout crystal, though not all experience symptoms.”
To obtain a proper diagnosis for pseudogout, other potential causes of symptoms (such as gout, RA, or infection) must be ruled out. The diagnosis is made on the basis of symptoms and through medical tests, including using a needle to take fluid from the swollen or painful joint to determine whether calcium pyrophosphate crystals are present. An X-ray of the joint may also be taken to determine if calcium-containing deposits are present, creating a condition known as chondrocalcinosis.