Calcium Pyrophosphate Deposition Disease

The reason that CPP crystals form in some people is unknown. The crystals occur in people who have the following:

• A previous joint injury (including surgery)

• Gout

• Accumulations of an abnormal protein in various organs and tissues (amyloidosis)

• An abnormally high calcium level in the blood caused by a high level of parathyroid hormone (An abnormally high calcium level in the blood caused by a high level of parathyroid hormone (hyperparathyroidism)

• An abnormally high iron level in the tissues (hemochromatosis)

• An abnormally low magnesium level in the blood (hypomagnesemia)

• Certain rare disorders including hypophosphatasia, Gitelman syndrome, hypophosphatemic rickets, and familial hypocalciuric hypercalcemia

• Older age

However, many people with CPPD disease have none of these conditions. The disorder rarely can be hereditary.

CPP crystals can frequently occur in joints affected by osteoarthritis for unclear reasons. However, CPP crystal deposits in a joint may not cause symptoms.

Symptoms of CPPD disease vary widely. Some people have attacks of painful joint inflammation (arthritis) similar to gout flares, usually in the knees, wrists, or other relatively large joints. Other people have lingering, chronic pain and stiffness in joints of the arms and legs, which may be similar to rheumatoid arthritis or osteoarthritis.

Compared to gout flares, attacks from CPPD disease vary more in intensity, tend to last longer, and are often more difficult to treat. As in gout, CPPD crystal arthritis attacks can cause fever. Some people have no pain between attacks, and some have no pain at any time, despite large deposits of crystals.

Unlike in gout, where collections of crystals often occur in tissues near joints, people with CPPD disease rarely develop hard lumps of crystals (tophi).

• Microscopic examination of joint fluid

• Sometimes x-rays or ultrasound

Doctors suspect CPPD disease in older adults with arthritis, particularly when joints are intermittently swollen, warm, and painful. Doctors confirm the diagnosis by removing a fluid sample from an inflamed joint through a needle (joint aspiration). CPP crystals are found in the joint fluid. They can be distinguished from uric acid crystals (which cause gout) using a special microscope with polarized light.

X-rays that show masses of crystals in a joint's cartilage may suggest the diagnosis. Ultrasound of the joint may show crystals in joint cartilage and strongly suggests the diagnosis of CPPD disease.

• Drainage of joint fluid and injection of a steroid (sometimes called a glucocorticoid or corticosteroid)

• Medications to relieve pain and swelling resulting from inflammation

• Physical therapy

Treatment of acute CPPD disease is similar to that for acute gout. Usually, treatment can stop acute attacks and prevent new attacks but cannot reverse changes in already damaged joints. Excess joint fluid can be drained and a steroid can be injected into the joint to rapidly reduce the inflammation and pain.

Medications taken by mouth help treat CPPD disease. Most often, nonsteroidal anti-inflammatory drugs (NSAIDs) are used to promptly stop the pain and inflammation of acute attacks.

Colchicine (see table Colchicine (see tableDrugs Used to Treat Gout) can be given by mouth in daily low doses (usually 1 or 2 pills) to try to limit the number of flares.

Steroids taken by mouth are effective at treating acute CPP arthritis flares and are particularly useful for some people who should not take NSAIDs or colchicine.Steroids taken by mouth are effective at treating acute CPP arthritis flares and are particularly useful for some people who should not take NSAIDs or colchicine.

If people cannot tolerate steroids, NSAIDs, or colchicine, drugs that suppress the immune system and inflammation (such as anakinra daily injections) can be effective.If people cannot tolerate steroids, NSAIDs, or colchicine, drugs that suppress the immune system and inflammation (such as anakinra daily injections) can be effective.

Unlike for gout, no specific effective long-term treatment of CPPD disease is available. However, physical therapy (such as muscle-strengthening and range-of-motion exercises) may be helpful to maintain joint function.

Often, the inflamed joints heal without any residual problems. However, in some people, chronic arthritis and permanent joint damage can occur over time, with some joints so severely destroyed that they can be confused with neurogenic arthropathy (Charcot joints).

Unlike gout, chronic CPPD disease is difficult to treat because there is no therapy that effectively eliminates or reduces the amount of CPP crystals. People who have frequent flares, especially younger people, are often evaluated for underlying diseases.