Tests & Diagnosis

Psoriatic arthritis is usually a seronegative disease, meaning the rheumatoid factor is negative and thus cannot be identified by blood tests.

However, x-rays of the hands, feet, pelvis and spine are reliable in testing for psoriatic arthritis providing visibility into the unique combination of changes that are characteristic of the disease, including bone erosion, bone production, spindle-shaped soft tissue swelling, joint space loss, joint destruction, and other indicators.

Among patients with psoriasis, changes to the nails are the most reliable sign of the onset of PSA, including:

  • Pitting, or multiple small depressions on the nail surface
  • Ridging, or raised, vertical lines on the nail surface
  • Growths under the nail
  • Cracking
  • Brown-yellow discolouration, or oil droplet spots
  • Separation of the nail from the underlying nail bed

Although mild variants of many of these signs are not uncommon in healthy individuals, people suffering from psoriasis should take care to monitor nail health and keep their physician informed of any significant changes.

Your doctor will take care to distinguish possible psoriatic arthritis symptoms from other, very similar diseases, such as:

  • Rheumatoid arthritis
  • Ankylosing spondylitis
  • Reactive arthritis
  • Other skin diseases
  • HIV