How is psoriatic arthritis diagnosed?

There is no specific test for psoriatic arthritis, but physicians will evaluate the following to diagnose the disease:

• Family history of psoriasis or psoriatic arthritis
• Signs such as swollen and tender joints, psoriasis skin lesions, and changes in nails
• Blood tests to rule out other diseases with a similar presentation (e.g., rheumatoid arthritis, gout, Lyme arthritis)
• Changes in joints or the spine using imaging tests such as x-rays, magnetic resonance imaging (MRI), or ultrasound