Evaluation of the interference due to haemoglobin, bilirubin and lipids on Immulite 2500 assays: a practical approach

Abstract

Background: Interfering substances such as haemoglobin, bilirubin and lipids in a sample may lead to wrong interpretation of immunoassay results by the clinician. In general, there has been minor attention to these interferences on immunoassays, whereas these effects on chemical assays are frequently described. Information about interferences by haemoglobin, bilirubin and lipids on the Siemens Immulite 2500 assays in the instructions for use is falling short. Methods: Interferents in patient samples can be measured reliably in a semi-quantitative way on most chemistry analysers and can be expressed in haemolysis-, icterus-and lipaemia-indices. As the Immulite 2500 cannot perform such measurements, samples are normally analysed without testing for the presence of interferents. Therefore, a study was carried out to examine these interferences on 24 Immulite 2500 assays. Samples were spiked with increasing concentrations of either haemoglobin, bilirubin or lipids. The haemolysis-, icterus-and lipaemia-indices were measured on a Synchron DxC 800 analyser. Results: Based on analytical imprecision and intraindividual biological variation of each analyte, cut-off indices above which clinically significant interference exists were determined. We found clinically significant interference due to haemoglobin on ferritin and folate, by bilirubin on oestradiol and testosterone and by lipids on testosterone. Conclusions: Introducing cut-off indices prevents reporting of wrong Immulite 2500 results due to interference. Our results are applicable in laboratories using any chemistry analyser capable of reporting semi-quantitative concentrations of interferents.

Investigation of unusual high serum indices for lipemia in clear serum samples on Siemens analysers Dimension

“…Unusual high lipemia indices were seen mostly in patients with multiple myeloma (24), Waldenström’s macroglobulinemia (11) and other lymphomas (8), leukemia (9), liver cirrhosis (9), cancer (7), MGUS (Monoclonal gammopathy of undetermined significance) (4), diabetes (4), and Sjögren syndrome (2). …”

“…(2) 1 sample aliquot was stored at −20 °C and serum index measured after 3 months. (3) 1 sample aliquot was stored at −20 °C and serum index measured after 12 months.…”

Proposal of Modified HIL-indices for Determining Hemolysis, Icterus and Lipemia Interference on the Beckman Coulter AU5800 Automated Platform

“…With this formula, the acceptability criteria would be approximately 2-3 times higher than the precision when biological variation is equal to or lower than the precision. This approach is statistically reasonable, and these criteria have been widely applied [6,10]. However, the within-subject variation is generally much larger than the analytical imprecision.…”

“…Although several studies have evaluated the interfering effects of hemolysis, icterus, and lipemia [4][5][6], there are only a few documents specifying the proper methods to perform interference studies [2]. In 2012, the Clinical and Laboratory Standards Institute (CLSI) published guidelines for HIL-indices to enhance the accuracy of reported patient test reports [7].…”

Lipaemia: Causes, consequences and solutions

“…Assay interference may also relate to the solubility of the antigen in the lipaemic serum which is unable to bind with the antibody [17].…”