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.
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.
In pseudogout, patients will experience symptoms similar to gout. Episodes or attacks of swelling, pain and redness of joints are common (Figure 1). Pseudogout often affects the wrists and hands but can happen in any joint. These episodes can be confused with infection.
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 (Figure 2). 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 (WBC) may be elevated in these conditions. Finally, it is helpful to check kidney function. Many of the drug treatments for psuedogout can be impacted by whether kidney function is normal or reduced. Therefore, it is important to know the health of the kidneys when recommending treatments.
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. They include:
© 2020 American Society for Surgery of the Hand
This content is written, edited and updated by hand surgeon members of the American Society for Surgery of the Hand. Find a hand surgeon near you.