Diagnosis of Psoriatic Arthritis
To diagnose psoriatic arthritis, rheumatologists look for swollen and painful joints, certain patterns of arthritis, and skin and nail changes typical of psoriasis. X-rays often are taken to look for joint damage. MRI, ultrasound or CT scans can be used to look at the joints in more detail.

Blood tests may be done to rule out other types of arthritis that have similar signs and symptoms, including gout, osteoarthritis, and rheumatoid arthritis. In patients with psoriatic arthritis, blood tests may reveal high levels of inflammation and mild anemia but labs may also be normal. Anemia is a condition that occurs when the body lacks red blood cells or has dysfunctional red blood cells. Occasionally skin biopsies (small samples of skin removed for analysis) are needed to confirm the psoriasis.