Evaluation of a particle-enhanced turbidimetric immunoassay for the measurement of immunoglobulin E in an ILab 900 analyzer

Background: The measurement of immunoglobulin E (IgE) in serum is widely us ed in the diagnosis of allergic reactions and parasitic infections. We desc ribe here a fully automated assay for human IgE suitable for routine applic ation in a general chemistry analyzer. Methods: We used an ILab 900(R) analyzer. This instrument automates a parti cle-enhanced immunoturbidimetric assay with an analysis time of 9 min. Results: The assay was linear in the range 4-1000 KIU/L (r = 0.9998). The i ntra- and interassay CVs at 57, 235, and 434 kIU/L were <3.5% and <7.4%, re spectively. The detection limit was 4 kIU/L. Hemoglobin (less than or equal to 16 g/L), bilirubin (less than or equal to 250 mu mol/L), and myeloma pa raproteins did not interfere with the assay. The assay showed good correlat ion with a microparticle enzyme immunoassay (r = 0.998) with a mean differe nce between methods of -6 +/- 26 kIU/L. Conclusion: The new automated serum assay for IgE is an attractive alternat ive that avoids the need for dedicated instrumentation. (C) 1999 American A ssociation for Clinical Chemistry.