Pseudogout - Other Types Of Arthritis: Arthritis

Content provided by the Faculty of the Harvard Medical School

Pseudogout

Pseudogout is a form of arthritis that occurs when a particular type of calcium crystal accumulates in the joints. As more of these crystals are deposited in the affected joint, they can cause a reaction that leads to severe pain and swelling. The swelling can be either short-term or long-term and occurs most frequently in the knee, although it can also affect the wrist, shoulder, ankle, elbow, or hand. The pain caused by pseudogout is sometimes so excruciating that it can incapacitate someone for days.

As its name suggests, the symptoms of pseudogout are similar to those of gout (see "Gout"). Pseudogout can also resemble osteoarthritis or rheumatoid arthritis. A correct diagnosis is vital, as untreated pseudogout can lead to joint degeneration and osteoarthritis. Pseudogout is most common in the elderly, occurring in about 3% of people in their 60s and as many as half of people in their 90s.

Causes of pseudogout

The cause of this condition is unknown. Because risk increases significantly with age, it is possible that the physical and chemical changes that accompany aging increase susceptibility to pseudogout. Certain medical conditions also make people more susceptible to pseudogout. These include an underactive thyroid (hypothyroidism), a genetic disorder of iron overload (hemochromatosis), or excessive blood levels of calcium (hypercalcemia). Pseudogout also can be triggered by joint injury, such as joint surgery or a sprain, or the stress of a medical illness. If the underlying condition causing pseudogout can be identified and treated, it may be possible to prevent future attacks. Frequently, however, there is no identifiable trigger; in those cases there is no way to prevent pseudogout from recurring.

Diagnosing pseudogout

It may be difficult to diagnose pseudogout because it shares so many symptoms with gout, infection, and other causes of joint inflammation. In fact, pseudogout often occurs in people with other joint problems, such as osteoarthritis. Therefore, even when pseudogout is correctly identified, it is important to investigate whether there are other conditions present as well.

Your doctor may order an x-ray of the inflamed joint in order to look for calcium deposits in the cartilage, although these deposits are sometimes present in healthy elderly people who do not experience the swelling that characterizes pseudogout. To verify the presence of calcium crystals, your doctor may remove a small amount of fluid from the affected joint. This is done with a needle, after applying a numbing medication to the joint. This joint fluid is then analyzed for evidence of calcium crystals, inflammation, or infection. Your doctor may also order tests for other conditions that can trigger pseudogout, including tests of calcium and thyroid function.

Treating pseudogout

To combat joint pain and swelling, your doctor may prescribe NSAIDs such as indomethacin and naproxen, or may give you glucocorticoid injections to keep the swelling down (see "Corticosteroid injections"). Your doctor may also remove fluid from the inflamed joint, a procedure called aspiration, as this may help to ease the pressure and inflammation.

The combination of joint aspiration and medication usually eliminates symptoms within a few days, although the doctor may also recommend treatment with oral corticosteroids over a short period of time. Daily use of a low-dose NSAID or colchicine, a medicine that is also used in the treatment of gout, may help to prevent further attacks. Unfortunately, there is no treatment available that can dissolve the calcium crystal deposits, although the joint degeneration that often goes along with pseudogout may be slowed by treatments that decrease joint swelling. Occasionally, people with recurrent or chronic pseudogout may develop osteoarthritis. In this case, surgery (such as joint replacement) may be the only effective treatment.

Last updated:	September 05, 2008