Urinary nitrate excretion as a marker of nitric oxide production in rheumatoid arthritis before and after corticosteroid therapy

Abstract EN

Twenty-four hours urinary nitrate was measured in 20 patients with RA as well as in 20 healthy controls.

This was performed before and 2 to 4 weeks after administration of prednisolone 0.5 mg/ kg body weight.

An enzymatic one-step assay with nitrate reductase was used.

Before the start of prednisolone therapy for RA patients, the urinary nitrate excretion was 3-fold greater than that in healthy volunteers (p < 0.001).

After prednisolone treatment it decreased significantly at which time inflammatory activity (as indicated by C- reactive protein, ESR, joint score and early morning stiffness) was also reduced considerably.

Despite this decrease, urinary nitrate excretion in patients with RA remained twice that in the control group (p < 0.05).

Our data suggest that the dramatic increase of urinary nitrate excretion could be due to an increase of Nitric Oxide (NO) synthesis in patients with RA.

This increased NO synthesis could be reduced by prednisolone treatment.

Assessment of NO production will help in our understanding of its role in inflammatory conditions such as RA.

Furthermore modulation of NO synthesis may represent a new approach to the treatment of inflammatory and autoimmune diseases.