What is pseudogout?
Pseudogout is a form of arthritis that causes pain, stiffness, tenderness, redness, warmth, and swelling (inflammation) in some joints. It usually affects one joint at a time, but sometimes it may affect several joints at once.
Pseudogout commonly affects the knee or wrist. Less often, it can involve the hips, shoulders, elbows, knuckles, toes, or ankles.
The symptoms of pseudogout are similar to the symptoms of other diseases, especially gout (which is why this form of arthritis is called pseudogout). Some symptoms of pseudogout are similar to the symptoms of rheumatoid arthritis or osteoarthritis.
Calcium Pyrophosphate Crystals
What are the symptoms of pseudogout?
- Sudden, intense joint pain
- Swollen joint that's warm and tender to touch
- Red or purple skin around the joint
Less often, pseudogout may cause persistent swelling, warmth, and pain in several joints, and can even mimic rheumatoid arthritis.
Most symptoms of pseudogout attacks stop within 5 to 12 days, even without treatment.
What causes pseudogout?
Pseudogout results from the abnormal formation of calcium pyrophosphate (CPP) crystals in the cartilage ("cushion" between the bones), which is later followed by the release of crystals into the joint fluid (synovial fluid). When CPP crystals are released into the joint, they can cause a sudden attack of arthritis, similar to gout.
The cause of abnormal deposits of CPP crystals in cartilage is often unknown. They may form due to abnormal properties of cells in the cartilage, or they may be produced as the result of another disease that damages cartilage. CPP crystals may be released from cartilage during a sudden illness, joint injury, or previous surgery. The abnormal formation of CPP crystals may also be a hereditary trait.
How frequent are pseudogout attacks?
Deposits of CPP crystals occur over a long period of time. Like gout, pseudogout attacks can recur from time to time in the same joint or different joints. The initial attack may last 5 to 12 days unless it is treated.
Over time, pseudogout attacks may occur more often, involve more joints, have more severe symptoms, and last longer. Frequency of attacks is quite variable. Attacks may occur from once every few weeks to less than once a year. However, frequent, repeated attacks can damage the joints.
Who is affected by pseudogout?
Pseudogout affects both men and women. Like gout, pseudogout occurs more frequently in people as they age, commonly affecting people over age 60.
People who have a thyroid condition, kidney failure, or disorders that affect calcium, phosphate, or iron metabolism have an increased risk for pseudogout. Pseudogout is also commonly present in people who have osteoarthritis. "Attacks" of osteoarthritis associated with pain, swelling, and redness of the joint may in fact be due to pseudogout.
Pseudogout in young patients is unusual. Its occurrence should lead the doctor to look for certain metabolic and hereditary disorders.
How is pseudogout diagnosed?
Pseudogout cannot be diagnosed simply from a blood test. It is diagnosed by the study of fluid from the inflamed joint, which is observed under a microscope for CPP crystals.
Fluid is removed through a needle from the inflamed joint. This procedure is called arthrocentesis. Removing the fluid may also help reduce the pressure within the joint and thereby reduce pain.
Since different types of crystals in the joint can be the cause of other forms of arthritis, it is important that an accurate diagnosis be made. Then, your doctor can prescribe the appropriate treatment.
How is pseudogout treated?
The treatment of pseudogout is similar to the treatment of gout, except uric acid-lowering drugs are not prescribed. Symptoms are often relieved within 24 hours after treatment – using anti-inflammatory medications -- has begun.
The goals of treatment are to relieve pain and inflammation, and prevent recurrent attacks that could lead to permanent joint damage.
The type of treatment prescribed will depend on several factors, including the person's age, type of other medicines he or she is taking, overall health, medical history, and the severity of the attack.
Anti-inflammatory drugs are usually continued until the pseudogout attack completely resolves. If side effects from the therapy occur, treatment may be changed to a different medicine. Your health care provider will discuss the potential side effects with you.
- Nonsteroidal anti-inflammatory drugs (NSAIDs) are generally prescribed to treat sudden and severe pseudogout attacks. NSAIDs usually reduce inflammation and pain within hours.
- Corticosteroids (also called steroids) may be prescribed for people who cannot take NSAIDs. Steroids also work by decreasing inflammation. Steroids can be injected into the affected joint or given as pills.
- Colchicine is sometimes used in low doses for a longer period of time to reduce the risk of recurrent attacks of pseudogout.
Side effects of medicines
Not all patients will develop side effects from these medicines. How often any side effect occurs varies from patient to patient. The occurrence of side effects depends on the dose, type of medicine, length of treatment, concurrent illnesses, and other medications the patient may be taking.
Some side effects are more serious than others. Before any medicine is prescribed, your health care provider will discuss with you the potential benefits and risks of taking the medications.
Pseudogout. American College of Rheumatology. www.rheumatology.org. Accessed June 2010
Calcium Pyrophosphate Dihydrate Crystal Deposition Disease (CPPD) (Pseudo Gout). www.arthritis.org. Accessed June 2010
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