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Objectives: Our three academic institutions, Indiana University, Northwestern Memorial Hospital, and Wake Forest, were among the first in the United States to implement the Beckman Coulter AU5822 series chemistry analyzers. We undertook this post-hoc multi-center study by merging our data to determine performance characteristics and the impact of methodology changes on analyte measurement., Design and Methods: We independently completed performance validation studies including precision, linearity/analytical measurement range, method comparison, and reference range verification. Complete data sets were available from at least one institution for 66 analytes with the following groups: 51 from all three institutions, and 15 from 1 or 2 institutions for a total sample size of 12,064., Results: Precision was similar among institutions. Coefficients of variation (CV) were <10% for 97%. Analytes with CVs >10% included direct bilirubin and digoxin. All analytes exhibited linearity over the analytical measurement range. Method comparison data showed slopes between 0.900-1.100 for 87.9% of the analytes. Slopes for amylase, tobramycin and urine amylase were <0.8; the slope for lipase was >1.5, due to known methodology or standardization differences. Consequently, reference ranges of amylase, urine amylase and lipase required only minor or no modification., Conclusion: The four AU5822 analyzers independently evaluated at three sites showed consistent precision, linearity, and correlation results. Since installations, the test results had been well received by clinicians from all three institutions., (Copyright © 2015. Published by Elsevier Inc.)

Immunoassays are widely used to determine hormone levels. Antibodies directed against components of the immunoassay system can interfere with analyte concentration estimates. When unrecognized by clinicians, inappropriate clinical intervention may follow. The case of a young child with premature thelarche and elevated basal and stimulated luteinizing hormone (LH) levels is presented, in whom it is hypothesized that heterophile antibodies (HAs) caused interference in the LH immunoassay. LH concentrations were measured in two different assays: LH-microparticle enzyme immunoassay (MEIA) and LH-immunochemiluminometric assay (ICMA). To detect HA interference, LH level was remeasured after both preincubation with mouse serum to neutralize human anti-mouse antibodies, and treatment with a heterophile-blocking tube. The mean basal LH concentration by LH-MEIA was 7.4 mIU/mL and for LH-ICMA was 0.08 mIU/mL (normal range for age: 0.02-0.3 mIU/mL). LH concentration by MEIA was 0.08 mIU/mL after preincubation with mouse serum and 2.7 mIU/mL after preincubation with a heterophile blocking tube. In conclusion, HAs were identified in the serum of a child with premature thelarche. The presence of HAs led to spuriously elevated basal and gonadotropin-releasing hormone-stimulated LH concentrations, resulting in a diagnosis of central precocious puberty and unnecessary therapy. To avoid similar cases in the future, clinicians should consider the possibility of assay interference when the clinical picture is incongruent with the laboratory data.

A high-performance liquid chromatography procedure for detection and quantitation of ethylene glycol in serum is described. Ethylene glycol and internal standard are derivatized with benzoyl chloride under alkaline conditions, purified by solid-phase extraction and analyzed by HPLC with UV detection. Analytical recovery of ethylene glycol ranges between 96 and 103%. The calibration curve is linear from 20 to 2000 mg/l. The limits of detection and quantitation are 10 and 20 mg/l, respectively. Assay imprecision is 4.8% or less. The assay is free from common interferences and provides increased sensitivity, improved precision and extended linearity.