Physical exams by a doctor are a first step in diagnosing psoriatic arthritis in an individual. During this exam, a physician will examine joints for signs of tenderness and swelling and will also closely examine the fingernails for evidence of flaking, grooves and other abnormalities. The feet and heels are also examined to determine if there is any discomfort or swelling.
While there is no one test that can confirm a diagnosis of psoriatic arthritis, there are a number of tests that may be used to rule out other causes of joint pain, such as gout or rheumatoid arthritis. They are as follows: imaging tests such as X-rays and MRI; and laboratory tests which can identify whether rheumatoid factor (known as RF) is present and what type of joint fluid is found.
With respect to RF, it is an antibody that is often found in the blood of those with rheumatoid arthritis but not those with psoriatic arthritis. The RF test is therefore helpful to doctors in distinguishing between the pair of conditions. Additionally, if a joint fluid reveals the presence of uric acid, an individual may be suffering from gout rather than psoriatic arthritis.