The Study of Urinary Hydroxypyridinium Crosslinks Concentrations in Patients with RA or OA , and Its Clinical Significance

Jung, Sung Kwang; Lee, Yun Woo; Shin, Bo Moon; Kim, Jong Won

Abstract

OBJECTIVES
To evaluate the urinary concentrations of hydroxyridinium crosslinks of collagen in patients with osteoarthritis(OA) or rheumatoid arthritis(RA), and to compare its clinical correlation with the classic indices of the disease activity of RA.
METHODS
Concentrations of urinary pyridinoline (Pyd) and deoxypyridinoline(Dpd) were measured in urinary samples collected from 18 control patients, 35 patients with OA, 45 patients with RA by competitive enzyme immunoassay using microplate coated with monoclonal antibody.
RESULTS
1) Mean urinary concentrations of Pyd in OA patients were 33.5nmol/mmol creatinine, in RA patients were 50.0nmol/mmol creatinine which were higher than the values in controls (25.1 nmol/mmol creatinine). Also, mean concentrations of Dpd in OA patients were 9.2nmol/mmol creatinine, in RA patients were 10.1nmol/mmol creatinine which were higher than the values in controls(5.6nmol/mmol creatinine)(p<0.01). 2) Mean urinary concentration of Pyd was 50.0 nmol/mmol creatinine in RA patients, which was significantly higher than the values in OA(33.5 nnmol/mmol creatinine)(p<0.05), but the mean Dpd concentratians were not significantly different between the two groups. 3) The concentrations of urinary Pyd in RA patients was significantly correlated with the biologic markers indicating inflammatory activity such as ESR(r=0.68, p<0.001), CRP(r=0.72, p<0.001) and the number of tender joint(r=0.66, p<0.01)
CONCLUSION
Urinary concentrations of Pyd and Dpd were significantly higher in OA and RA patients than in controls, Especially urinary Pyd concentrations were significantly increased in RA patients than in OA patients, and strongly correlated with disease activity index of rheumatoid arthritis. The mean Dpd concentration, bone specific analogue, in RA patients was not significantly different from that of OA patients and it was not correlated with disease activity index Thus measurement of urinary Pyd might provide a sensitive, noninvasive biochemical marker for studying activity of RA.