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

Herbert S Diamond, MD; Anwar Al Hammadi, MD


July 10, 2019

The most characteristic laboratory abnormalities in patients with psoriatic arthritis are elevations of the erythrocyte sedimentation rate and C-reactive protein level. The results of these laboratory tests help to track disease activity by measuring inflammation.

An elevated erythrocyte sedimentation rate is found in approximately 40% of patients with psoriatic arthritis. An erythrocyte sedimentation rate greater than 15 mm/h, along with medication use before the first clinical visit, evidence of radiologic damage, and absence of nail lesions, has been associated with increased mortality in patients with psoriatic arthritis.

Patients with psoriatic arthritis are typically seronegative for rheumatoid factor, although it is detected in 5%-9% 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 psoriatic arthritis and in one third of patients with psoriasis.

For more on the workup for psoriatic arthritis, read here.


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