Fast Five Quiz: Can You Identify Psoriatic Arthritis and Initiate the Best Treatment Practices?

Herbert S Diamond, MD; Anwar Al Hammadi, MD


July 14, 2021

There are no laboratory tests that are specific for PsA. Acute phase reactants such as ESR and CRP may become elevated, as they do in most inflammatory diseases. However, a normal ESR and CRP should not be used to rule out a diagnosis of PsA, as these levels increase in only about 40% of patients.

Patients with PsA are typically seronegative for rheumatoid factor, although it is detected in 2%-10% of patients. Rheumatoid factor testing is usually associated with a high false-positive rate; thus, patients with positive and negative findings should undergo the same treatment.

Serum IgA levels are increased in two thirds of patients with PsA and in one third of patients with psoriasis.

Learn more about the workup for PsA.


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