Calcium Pyrophosphate Dihydrate Deposition Disease (CPPD, or Pseudogout)
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.
Symptoms and Causes
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.
Diagnosis and Tests
How is calcium pyrophosphate dihydrate crystal deposition disease (CPPD, or pseudogout) diagnosed?
CPPD can't be diagnosed simply from a blood test. It's diagnosed by the study of the synovial fluid from the inflamed joint, which is observed under a microscope for CPPD crystals.
Fluid is aspirated 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 this can help reduce the pain.
Since different types of crystals in the joint can be the cause of other forms of arthritis, it's important that an accurate diagnosis be made. Then your doctor can prescribe the appropriate treatment.
The diagnosis of CPPD can be suspected by certain X-rays and imaging studies or computed tomography (CT), but the findings of CPPD crystals on synovial fluid analysis leads to a more definite diagnosis.
Management and Treatment
How is calcium pyrophosphate dihydrate crystal deposition disease (CPPD, or pseudogout) treated?
The treatment of CPPD is similar to the treatment of acute gout attacks with anti-inflammatory medication. Uric acid-lowering drugs are not prescribed. Symptoms are often relieved within 24 hours after beginning treatment with anti-inflammatory medications.
The goals of treatment are to relieve pain and inflammation, and prevent recurrent attacks that could lead to significant pain and joint damage.
The type of treatment prescribed will depend on several factors, including the person's age, type of other medicines they're taking, overall health, medical history and the severity of the attack.
Anti-inflammatory drugs are usually continued until the CPPD attack completely resolves. If side effects from the therapy occur, treatment may be changed to a different medicine. Your healthcare provider will discuss the potential side effects with you.
- Colchicine is usually prescribed for CPPD attacks. At low doses, it can be prescribed for a longer period of time to reduce the risk of recurrent attacks of CPPD.
- Nonsteroidal anti-inflammatory drugs (NSAIDs), especially if colchicine cannot be prescribed, are used to treat CPPD attacks. Certain patients cannot take these medications, such as those who have poor kidney function, bleeding disorders, stomach or digestive disease, heart disease and certain other health complications. Types of NSAIDs include aspirin, ibuprofen and naproxen.
- Corticosteroids (also called steroids) may be prescribed for people who cannot take NSAIDs or colchicine. Steroids also work by decreasing inflammation. Steroids can be injected into the affected joint or given as pills. (Steroids shouldn't be used in certain cases.)
- Certain medications, such as anakinra and canakinumab, have been shown to be beneficial in the treatment of the acute attack. However, as of 2020 these have not yet been approved by the FDA.
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 healthcare provider will discuss with you the potential benefits and risks of taking the medications.
Outlook / Prognosis
How frequent are attacks of calcium pyrophosphate dihydrate crystal deposition disease (CPPD, or pseudogout)?
Deposits of CPPD crystals occur over a long period of time. Like gout, CPPD attacks can recur from time to time in the same joint or different joints. The initial attack may last a week to two weeks (or sometimes even longer) unless it's treated.
Over time, CPPD attacks may occur more often, involve more joints, have more severe symptoms and last longer. Frequency of attacks varies. Attacks may occur from once every few weeks to less than once a year. However, frequent, repeated attacks can damage the joints.
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