The Establishment and Validation of Reference Intervals for Plasma Pentraxin-3 in Healthy Volunteers and Patients with Takayasu's Arteritis

Objective To establish reference intervals (RIs) for PTX-3 and to validate the performance of these RIs in a population including healthy volunteers and Takayasu's arteritis (TAK) patients. Methods Enzyme-linked immunosorbent assays were used to determine the plasma PTX-3 levels of 166 healthy volunteers and 63 TAK patients. RIs were established in healthy volunteers according to guidelines from the Clinical and Laboratory Standards Institute (CLSI, C28-A3). Global assessment was used to quantitatively diagnose active/non-active TAK patients. PTX-3 cut-off values and RI-derived values were calculated as candidate standards for quantitative diagnosis. Screening and monitoring performances were validated by identifying active TAK patients from the whole population or diagnosed TAK patients. Traditional inflammatory markers C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were included in the comparison. Results PTX-3 level increased with age but were not significantly different among different age or gender groups (p > 0.05). The PTX-3 RI was calculated to be 0.87–2.78 ng/mL (RI median: 1.66 ng/mL). For screening purposes, the cut-off value (1.55 ng/mL) had a high sensitivity of 90.32% and the RI upper limit (2.78 ng/mL) had a high specificity of 97.94%. For monitoring purposes, the sensitivity/specificity of the cut-off value (1.55 ng/mL) and RI median were 90.32%/90.63% and 80.85%/90.63%, respectively. These screening and monitoring performances of PTX-3 were superior to those of CRP and ESR. Conclusion The distribution of serum PTX-3 levels was stable and uniform across the population. The screening and monitoring performances of the cut-off value and RI-derived values of PTX-3 were higher than CRP and ESR.