Collection Tubes Can Cause False Elevations in Occupational and Clinical Evaluation of Antimony Exposure.

Occupational exposure to antimony has become rare in the past decades due to antimony mine closures and technological improvement in antimony processing plants in the USA. Although antimony's ubiquitous presence in plasticwares does not pose known health risk, it can present as a potential contaminant to antimony analysis for occupational exposure assessment. To understand the level of antimony contamination from plastic collection devices, we evaluated two different whole-blood plastic collection tubes that are routinely used for trace and toxic element assessment: royal blue BD Vacutainer® EDTA tube and Greiner VACUETTE® trace elements sodium heparin tube. We analyzed how different fill volumes may impact the concentrations of antimony detected. Although both collection tubes can introduce antimony contaminations to nitric acid and neutral buffer rinse, the Greiner heparin tube introduces a significantly lower amount of antimony to freshly collected whole-blood samples compared to the BD EDTA tube. When patients' samples are collected with BD EDTA tubes, they would exhibit elevated antimony concentrations that can be interpreted as potential antimony exposure. We conclude that the royal blue BD EDTA plastic tube is not suitable to evaluate blood antimony levels, and laboratories need to validate their own alternative sources when the glass tubes are not available.

Have you caught that outlier yet? Evaluate the utility of repeat testing in nutritional and toxic element assessment.

Repeat testing is routinely required by regulatory bodies as a measure to rule out contamination in trace elements and heavy metal analysis, especially when the initial analysis result is outside the reference interval. However, its clinical utilities in detecting analytical measurement outliers have not been systematically evaluated in different clinical testing scenarios. In this study, we present an extensive evaluation of repeat testing and its comparison with the initial analysis in four serum and plasma trace element assays performed by inductively coupled plasma mass spectrometry. We demonstrate that the patient population distributions for these elements differ significantly from the reference interval established by healthy individuals. Accordingly, a significant proportion of the patient specimens would require repeat testing when using reference intervals as the threshold to perform repeat analysis. Crucially, comparison of the first analysis and repeat analysis reveals the limited utility of performing repeat measurements. The relative differences between the first and second measurements are consistent with the observed analytical imprecision of the assay and the likelihood of detecting actual analytical outliers is very low.