What to Know About Pseudogout

Pseudogout or calcium pyrophosphate dehydrate deposition (CPPD) disease, occurs when calcium crystals collect in joints. It is a painful joint condition that can be treated, though not cured, and is often mistaken for gout or another rheumatic condition. Hence, it is important to get an accurate diagnosis. Untreated pseudogout can result in severe joint degeneration, chronic inflammation, and chronic disability. Here are 10 important things to know about this condition and how it differs from gout.

Crystals Are Not Uric Acid

As its name suggests, pseudogout is similar to gout. However, gout develops when uric acid crystals are deposited in the affected joint, while pseudogout develops when calcium pyrophosphate (CPP) crystals accumulate in the joints and surrounding tissues. The deposits provoke inflammation in the joint, which can cause the joint cartilage to break down.

Its Cause Is Unknown

It is unclear what causes CPP crystals to form. They may form due to abnormal cells or be produced as a result of another disease; genes may also play a role. Often, CPP crystals exist without causing problems. Symptoms occur when the crystals are released from cartilage into the surrounding joints. Crystals can be released during sudden illness, joint injury, surgery, or for no known reason at all.

Symptoms Overlap With Other Conditions

About 25 percent of people with CPP deposits develop pseudogout symptoms. Both pseudogout and gout can appear suddenly, causing hot, red/purple, or swollen joints that are painful to move; sometimes these symptoms can resolve spontaneously. Pseudogout usually lasts anywhere from several days to two weeks and may be accompanied by fever. 

The Joints Affected Differ

Nearly half of all pseudogout attacks occur in the knee, while the big toe is most commonly affected by gout. Pseudogout can develop in any joint, though, including the ankle, wrist, and even the big toe; usually, only one or two joints are affected at a time. In some cases, pseudogout can co-occur with gout. This happens when the two types of crystals are found in the same joint.

Age Raises the Risk of Pseudogout

Anyone can develop pseudogout, but the risk increases significantly with age. The crystal deposits associated with pseudogout affect about 3 percent of people in their 60s. The percentage increases to about 50 percent of people in their 90s. (Again, not all people with the crystals will develop symptoms.) The condition is equally prevalent among women and men. 

The risk of developing the condition is also increased if the patient has any of the following metabolic disorders:

• Hyperparathyroidism
• Hemochromatosis
• Hypothyroidism (underactive thyroid)
• Amyloidosis
• Hypomagnesemia (magnesium deficiency)
• Hypophosphatasia

Additional risk factors include:

• Dehydration
• Hemophilia
• Ochronosis (a disease of the connective tissues)
• High iron levels 
• Hypercalcemia (excessive calcium in the blood)

It's Important to Be Diagnosed by a Specialist

Because pseudogout can mimic other types of arthritis, it is important to be evaluated by a rheumatologist—a specialist in arthritis and related rheumatic diseases. An early, accurate diagnosis provides the best chance to prevent severe joint damage.

The Joint Fluid Test Is the Gold Standard

The most significant diagnostic test for determining pseudogout is a joint fluid examination. Joint fluid is drawn from the affected joint and examined for rod-shaped or rhomboid-shaped CPP crystals (weakly positively birefringent rhomboid crystals).

Based on the observation of these crystals, the diagnosis can be confirmed. X-ray evidence also supports the diagnosis when chondrocalcinosis (calcification of cartilage) is detected. If needed, more lab tests can be performed to rule out other types of arthritis.

Symptoms Can Be Controlled but Not Cured

There is no cure for pseudogout, but medications can treat the symptoms. Nonsteroidal anti-inflammatory (NSAIDs) are usually prescribed to control pain and inflammation during pseudogout attacks. For the purpose of preventing further attacks, low doses of Colcrys (colchicine) and NSAIDs are typically prescribed, along with recommendations for proper hydration. Cortisone shots into the affected joint may be another option for controlling pain and inflammation, especially for people who cannot use the other medications. Surgery is also an option for severely damaged joints.

Diet Has No Effect on Pseudogout 

Whereas gout is often exacerbated by consuming meat, seafood, and alcohol, diet does not affect the onset or development of pseudogout or control symptoms. Though the crystals associated with pseudogout are partly calcium, it is a myth that consuming foods high in calcium provokes the development of pseudogout. 

Untreated Pseudogout Can Cause Joint Damage

If left untreated, pseudogout crystals in the ligaments and cartilage can lead to joint injury and a loss of normal motion and function in affected joints. 

A Word From Verywell

Proper treatment depends on a proper diagnosis. While that can be said of any disease or condition, it is especially true when there are overlapping symptoms or when one condition mimics another. See your healthcare provider if you experience a suddenly painful joint.