Causes and Diagnoses

Causes and Diagnoses of Psoriatic Arthritis

Although the cause of psoriatic arthritis is unknown, factors such as immunity, genetics and the environment may play a role. Psoriatic arthritis is an autoimmune disorder, which means the body's immune system attacks its own healthy cells and tissues. The response of the body causes inflammation in and around the joints, which may then lead to a destruction of the skeletal system.


When psoriasis has been already been diagnosed, a diagnosis of psoriatic arthritis may be easily confirmed. However, when psoriatic arthritis symptoms precede the symptoms of psoriasis, diagnosis is more difficult.

The most common diagnostic test is a blood test. Psoriatic arthritis sometimes causes an increased erythrocyte sedimentation rate (ESR), a measurement of how quickly blood cells fall to the bottom of a test tube. When swelling and inflammation are present, the blood's proteins clump together and become heavier than normal. Thus, when measured, they fall and settle faster at the bottom of the test tube. Generally, the faster the blood cells fall, the more severe the inflammation.

In addition to increased ESR, psoriatic arthritis can be accompanied by mild anemia and elevated blood uric acid levels, although all of these symptoms are also associated with other rheumatic diseases, including gout.