The relationship between nitric oxide and peroxynitrite levels and disease activity parameters in spondylarthritis

86 SpA patients ( 35 ReA, 26 AS, 12 PsA, 3 EA), of whom 49 were female and 37 were male, and 60 healthy controls were evaluated in order to asses the association between the nitric oxide in urine & serum samples & peroxinitrite levels in serum samples and the disease activity parameters and the clinical & laboratuary paremeters. Disease duration, duration of morning stiffness, family history, peripheral joint involvement and presence of entesitis were recorded. Muscle skeletal system was evaluated, and laboratory analysis were recorded along with the presence of sacroiliitis. Total nitric oxide metabolites ( nitrate plus nitrite) in serum and urine samples were measured using Griess method while nitrotyrosine levels, indicator of peroxynitrite in serum, were measured by enyzme immunoassay method. Severity of entesitis was measured using MEI. BASDAI was used for AS patients while Disease Activity Index for the assessment of reactive arthritis (DAREA) was used for ReA patients. AS patients were also assessed using Bath Ankylosing Spondiylitis Functional Index (BASFI). Mean age of the patients was 44,3±10,3 years. There were no significant age and gender differences between the patient and control groups. Although serum NO levels of the patients were low compared to the control group, their urine NO and peroxynitrite levels were higher than those of controls. Among subgroups, urine NO and peroxinitrite levels of ReA and AS patients were significantly higher than the levels observed in the controls. Urine NO levels of ReA patients were found correlated with CRP, ESR and DAREA. Peroxysinitrite levels of ReA patients were found associated with CRP and DAREA too. No significant association was found between serum NO, urine NO & peroxynitrite levels and disease activity parameters in other SpA subgroups. Taken all these information together; serum NO levels were found not to be sensitive to assess the disease activity and NO and prexynitrite levels were not associated with the disease activity in SpA subgroups (except ReA); however, urine NO and peroxynitrite levels can be markers in assessing the disease activity in ReA patients.