C reactive protein rapid assay techniques for monitoring resolution of infection in immunosuppressed patients

Three rapid assay techniques (latex agglutination, laser nephelometry, and EMIT enzyme immunoassay) have been evaluated for serial monitoring of the serum C reactive protein (CRP) concentration in immunosuppressed patients with fever. Radial immunodiffusion assay was used as a reference method. Latex agglutination reliably distinguished between normal and raised serum CRP concentrations. Enzyme immunoassay also provided a result within minutes, showed particularly close correlation (r = 0.967) with the reference method, and was free from interference by lipaemic or icteric sera. In 27% of 55 episodes of fever studied serially in immunosuppressed patients, the enzyme immunoassay provided clinically useful information by indicating incomplete resolution of infection despite resolution of fever.