What is calcium pyrophosphate dihydrate crystal deposition disease (CPPD, or pseudogout)?

Calcium pyrophosphate dihydrate crystal deposition disease (CPPD) 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.

The symptoms are similar to the symptoms of other diseases, especially gout (which is why this form of arthritis had the old name of pseudogout – “false gout”). Some symptoms of CPPD may appear to be symptoms of rheumatoid arthritis or osteoarthritis.

CPPD commonly affects the knee or wrist. Less often, it can involve the hips, shoulders, elbows, knuckles, toes or ankles. Rarely it affects the neck and causes neck, shoulder pains, headaches and in some cases fevers. This occurs when the calcium crystals deposit around the dens part of the second cervical vertebra. The condition is called crowned dens syndrome.

Who is affected by CPPD?

CPPD affects both men and women. It occurs more frequently in people as they age, commonly affecting people over age 60.

People who have an increased risk for CPPD include those with:

  • A thyroid condition.
  • · Kidney failure.
  • · Parathyroid disease.
  • · Low magnesium.
  • · Disorders that affect calcium, phosphate or iron metabolism (such as hemochromatosis).

The condition is also commonly present in people who have osteoarthritis/degenerative joint disease. "Attacks" of osteoarthritis associated with pain, swelling and redness of the joint may in fact, in certain cases, be due to CPPD.

CPPD in young patients is unusual. Its occurrence should lead the doctor to look for certain metabolic and hereditary disorders.

What are the symptoms of acute calcium pyrophosphate dihydrate crystal deposition (CPPD, or pseudogout)?

  • Sudden, intense joint pain.
  • Swollen joint that is warm and tender to touch.
  • Red skin involving the affected joint.

Less often, CPPD may cause persistent swelling, warmth and pain in several joints, and can even mimic rheumatoid arthritis.

What causes CPPD?

This condition results from the abnormal formation of calcium pyrophosphate dihydrate (CPPD) crystals in the cartilage (cartilage is the "cushion" between the bones) or the joint fluid (synovial fluid). This can lead to a sudden attack of arthritis similar to gout.

The cause of abnormal deposits of CPPD crystals in cartilage is often unknown. CPPD crystals may be seen associated with some underlying disorders such as injury to the joint, hyperparathyroidism, hypomagnesemia, hypophosphatasia, hypothyroidism and hemochromatosis. The abnormal formation of CPPD crystals may also be a hereditary trait.

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