Investigations of Psoriatic Arthritis
The Erythrocyte Sedimentation Rate (ESR) is elevated. Serum Uric Acid may be elevated in a few patients.
Anti Nuclear Antibodies (ANA) and Rheumatoid Factor (RA) are usually negative.
X-Ray Findings:
The DIP joints of fingers and the interphalangeal joints of the toes show erosions.
Bony Ankylosis of the DIP joints of the hands and the toes, along with the bony proliferation of the base of the distal phalanx, and the Resumption of the tufts of the distal phalanges of the hands and feet are seen.
Fluffy periostitis of the large, "pencil in cup" appearance of the DIP joints, the absence of symmetry, and gross destruction of isolated small joints are also seen.
Radiographically, spine changes and sacroiliac joint changes appear similar to in Ankylosing Spondylitis but are often unilateral in Psoriatic Arthritis.
Magnetic Resonance Imaging (MRI) is more effective to detect enthesitis and early articular and periarticular involvement.