Nitroblue tetrazolium test in psoriatic arthritis, rheumatoid arthritis, and osteoarthrosis.

Nitroblue tetrazolium test scores were obtained in 43 patients with psoriatic arthritis, 32 patients with rheumatoid arthritis, and 16 patients with osteoarthrosis. The mean score in all groups was similar and was higher than previously reported in patients awaiting heart surgery or with noninfective dermatoses. The test is not thought to be helpful in differentiating psoriatic arthritis from rheumatoid arthritis, and its usefulness in the diagnosis of septic arthritis superimposed on other forms of arthropathy is limited.