Evaluation of determination of theophylline concentrations by Seralyzer

Determination of theophylline concentrations by Seralyzer in 28 paired serum and plasma samples disclosed almost identical results. Comparison of determinations by Seralyzer and enzyme-multiplied immunoassay in 31 paired serum samples disclosed significant underestimation by Seralyzer when recalibrated whenever results of analysis of a 15-micrograms/mL control exceeded limits of +/- 3 micrograms/mL. Determinations by Seralyzer did not differ significantly from enzyme-multiplied immunoassay with narrower limits of 15 +/- 2 micrograms/mL for Seralyzer calibration for 18 paired samples. Seralyzer results are sufficiently reliable for clinical use if the instrument is recalibrated whenever analysis of the 15-micrograms/mL control falls outside limits of +/- 2 micrograms/mL.