What is pseudogout?
Pseudogout (SOO-doe-gout) is a form of arthritis caused by calcium pyrophosphate crystal deposits in a joint, most commonly the knee. It is characterized by sudden and intense redness, warmth, pain, and swelling in one or more joint.
Pseudogout is also called calcium pyrophosphate deposition disease or CPPD. The name pseudogout indicates its similarity to gout, which is also caused by crystal deposits within a joint. However, gout is caused by uric acid crystals and most commonly affects the base of the first toe, and pseudogout is caused by calcium pyrophosphate crystals and most commonly affects the knee.
Pseudogout generally affects older adults. Though both men and women get arthritis from calcium pyrophosphate crystals, the pseudogout form of arthritis is more commonly seen in men. Pseudogout sometimes occurs in the setting of trauma, surgery, or acute medical illness, but may not have any obvious cause. The knee is most often affected but shoulders, elbows, wrists, ankles, and feet may also be involved.
What causes pseudogout?
Many people, especially older people, have calcium pyrophosphate crystals in their cartilage and joint fluid. The crystals may stay there forever, causing no harm. However, for reasons we don’t understand, sometimes these crystals provoke a sudden and severe inflammatory response. White blood cells rush into the joint space, treating the crystals as if they were bacteria invading the joint and trying to destroy them. When this happens, the result is marked redness, warmth, swelling, and pain. This is more likely to happen in the setting of physiologic stress, such as surgery or acute medical illness, but sometimes it occurs for no apparent reason.
What are the symptoms of pseudogout?
In pseudogout, warmth, redness, swelling, and intense pain develop in a joint over the course of several hours or a day. Usually only one joint is affected. The knee is the joint most commonly involved, but most other joints can be affected. It is less common but not impossible for several joints to be affected at once. Occasionally, the sufferer will develop a low grade fever as well. Most of the time, these symptoms will resolve within a week, even without treatment.
However, if you experience inflammation in a joint as described above, you should see your doctor right away. It is impossible to tell the difference between various forms of arthritis from the outside: for example, pseudogout, gout, and infection are indistinguishable from the outside. Yet different forms of arthritis require different treatment and infection requires antibiotics right away.
How is pseudogout diagnosed?
There are many different forms of arthritis, and to narrow the list down to a few possibilities your rheumatologist will ask you detailed questions about your symptoms. How long have you been experiencing these symptoms? Which joints are affected? Have you taken any medicine to feel better, and do you think it helped? Have your symptoms evolved over time? Has this ever happened to you before? Do you think there is anything that might have triggered your symptoms? You will also be asked about your medical history, what medications you take, and whether anyone else in your family has arthritis. Your rheumatologist will also examine you, looking for clues.
Ultimately, though, the best way to diagnose pseudogout is to remove fluid from the joint space and to examine it under a microscope. Seeing calcium pyrophosphate crystals that have been engulfed by white blood cells in the joint fluid gives a certain diagnosis of pseudogout. Analysis of joint fluid also allows the physician to search for gout and for infection. Removing joint fluid is a simple procedure that can be done in the office using local anesthesia and a needle similar to the needle used to draw blood. It takes only a few minutes.
How is pseudogout treated?
Though gout and pseudogout generally resolve on their own without treatment, they get better much more quickly with medication. Also, a person who has repeated episodes of gout or pseudogout may want to take something on a daily basis to prevent future attacks.
It is important to make a clear diagnosis of pseudogout to allow for the best treatment plan. The right medication depends in part on the severity of your symptoms and in part on your other medical illnesses and other medications you take.
There are 3 kinds of medicines that treat acute attacks of pseudogout. Nonsteroidal anti-inflammatory drugs such as ibuprofen or naproxen are effective. Colchicine can also bring the inflammation under control. Steroids, either by mouth or injected directly into the joint, are also highly effective. However, each of these medicines has its risks as well as its benefits, and treatment should be tailored to each individual patient. If a person has repeated attacks of pseudogout, the same medications can be used to prevent attacks as well.