Reference interval for serum C-reactive protein in healthy blood donors using the Dade Behring N Latex CRP mono assay

Measurement of the serum concentration of the acute-phase reactant C-reacti ve protein (CRP) provides an useful objective marker in clinical practice, both in screening for diseases and in monitoring disease activity and respo nse to therapy. The aim of this study was to evaluate the analytical perfor mance of the assay in the concentration range from 0.2 to 15 mg/L, and to d etermine a reference interval for serum CRP in healthy blood donors using t he Dade Behring N Latex CRP mono assay on the Dade Behring Nephelometer II. The assay is a particle-enhanced nephelometric immunoassay with a measurin g range of 0.2-1100 mg/L. The sample volume is 40 mu L, and the assay time is 6 min. The coefficients of variation for within-run and between-run impr ecision studies were between 2.2 and 5.4% in serum pools with CRP concentra tions between 1.29 and 11.98 mg/L. Linearity studies showed excellent corre lation between the theoretical and the measured values. No interferences we re detected from hemoglobin <1.0 mmol/L, bilirubin <512 mu mol/L and Intral ipid(R) <20 g/L. Blood samples were collected from 268 healthy blood donors (107 females and 161 males) between 20 and 65 years old. The non-parametri c reference intervals for serum CRP was calculated to be <0.2-14.7 mg/L in females and <0.2-9.16 mg/L in males. The Mann-Whitney U-test revealed no ge nder-related difference for serum CRP (p-value = 0.72). A common reference interval for serum CRP for both genders was calculated to be <0.2-10.5 mg/L (median 0.98 mg/L, range <0.2-17.3 mg/L).