Pseudogout

Swollen red painful finger during an acute pseudogout episode
Figure 1: Acute pseudogout episode with a swollen, red and painful finger.

Pseudogout is a disease that causes joint inflammation and arthritis. If someone develops pseudogout, they form and react to calcium pyrophosphate (CPP) crystals. These crystals can deposit in the joints and soft tissues. Pseudogout is also called calcium pyrophosphate disease (CPPD). Chondrocalcinosis is another word used to describe these calcium crystals. It is considered a rheumatologic condition.

This condition affects the body in a similar way to gout in hands. In each of these crystal forming conditions, the body’s reaction to the crystals can result in cartilage and soft tissue damage.

Causes

The reason that the crystals form is unknown. There may be a genetic cause. This means you inherited a way your body processes calcium crystals. Certain risk factors are seen with pseudogout. For example, it occurs more often in men over 60 years of age. Other risks include thyroid disorders, kidney failure, or disorders of calcium or iron metabolism.

Sudden attacks of pseudogout are related to the release of crystals within the joint fluid. These crystals are attacked by the body’s own defense cells. Polymorphonuclear neutrophils (PMNs) are a type of white blood cell. White blood cells often fight infection. But, they also react to the crystals. Macrophages are another type of white blood cell that ingest bacteria and crystals. These white blood cells often release toxic chemicals designed to kill bacteria. These chemicals can accidentally injure the surrounding tissue and cartilage, causing inflammation that results in severe pain, swelling and redness.

Signs and Symptoms

In pseudogout, patients will experience symptoms similar to gout. Episodes or attacks of swelling, pain and redness of joints are common. Pseudogout often affects the wrists and hands but can happen in any joint. These episodes can be confused with infection.

Wrist x-ray showing fluffy white deposits associated with pseudogout
Figure 2: An x-ray of the wrist can show fluffy white deposits like those shown here.

Diagnosis

The diagnosis of pseudogout can be tricky. Your doctor will ask about your pain and medical history. They will examine many of your joints. This will include joints that hurt and ones that do not hurt to look for patterns. The doctor may order x-rays of an involved joint, which may show crystal deposits within the soft tissue. The most definitive way to make the diagnosis is to remove fluid from a joint and analyze it in a lab. This is very important to help distinguish it from an infection.

Gout and pseudogout crystals can be seen with a microscope. Each type of crystal looks different when viewed in a special polarized light. Each crystal has a unique shape and appearance. Gout crystals are shaped like a needle, while pseudogout crystals are rhomboid shaped. If there are no bacteria seen under the microscope, it suggests there may not be an infection. With no bacteria, definite calcium crystals, and PMNs, this pattern suggests pseudogout is present. Sometimes both a crystal problem and an infection can coexist.

The x-rays can also be helpful, as they show different changes. Gout eats away at the bones and joints of the hand and wrist. This is noticed with many small cystic erosions in the bones at the joint surfaces. An x-ray showing pseudogout may show calcification in the soft tissues around the joints. Blood levels of urate are often elevated in gout, and uric acid is normal in pseudogout. The white blood cell count may be elevated in these conditions. Finally, it is helpful to check kidney function. Many of the drug treatments for pseudogout can be impacted by whether kidney function is normal or reduced.

Treatment

Initial treatment includes rest and ice to the painful joint. There is no medication that can directly reduce the amount of crystals in tissue. However, there are treatment options that can improve pain and inflammation.

  • Edema control: Light compression, ice, elevation, motion as pain permits, and therapy may help reduce swelling and improve function.
  • Splints: Splints can improve pain by limiting painful joint and tendon motion. They should only be used for a short time because longer use can cause stiffness.
  • NSAID medications: Ibuprofen or naproxen may reduce swelling and pain, but they may have risks in elderly patients, patients with decreased kidney function, or patients taking blood thinners.
  • Steroids: Steroids are a common and effective treatment. They may be taken by mouth or given by injection, depending on the severity of the attack.
  • Colchicine: This medication can be used to treat a painful attack. Diarrhea can occur as a side effect, and low-dose colchicine may sometimes be used to help prevent future attacks.
  • Immunosuppressive medications: Stronger medicines may be used when other medications are not successful and should be managed by an experienced health care provider.
  • Surgery: Surgery is rarely performed early, but in selected cases it may be used to remove crystals, help confirm the diagnosis, improve pain, and reduce cartilage damage.
  • Magnesium supplements: There is a small chance that daily magnesium supplements could decrease the chance of developing pseudogout.

This mobile-friendly version is adapted from patient education content originally provided by the American Society for Surgery of the Hand.