Bilirubin measurements in neonates: uniform neonatal treatment can only be achieved by improved standardization.

Measurement of total bilirubin (TBil) concentration in serum is the gold standard approach for diagnosing neonatal unconjugated hyperbilirubinemia. It is of utmost importance that the measured TBil concentration is sufficiently accurate to prevent under treatment, unnecessary escalation of care, or overtreatment. However, it is widely recognized that TBil measurements urgently require improvement in neonatal clinical chemistry. External quality assessment (EQA) programs for TBil assess for differences between laboratories and provide supporting evidence of significant differences between various methods, manufacturers and measurement platforms. At the same time, many countries have adopted or only slightly adapted the neonatal hyperbilirubinemia management guidelines from the USA or UK, often without addressing differences in the methodology of TBil measurements. In this report, we provide an overview of the components of bilirubin that are measured by laboratory platforms, the availability of current reference measurement procedures and reference materials, and the role of EQA surveys in this context. Furthermore, the current status of agreement in neonatal bilirubin against clinical decision thresholds is reviewed. We advocate for enhancements in accuracy and comparability of neonatal TBil measurements, propose a path forward to accomplish this, and reflect on the position of the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) Working Group Neonatal Bilirubin (WG-NB) in this matter.

Evolution and impact of Standard Reference Materials (SRMs) for determining vitamin D metabolites.

The National Institute of Standards and Technology (NIST), in collaboration with the National Institutes of Health, Office of Dietary Supplements (NIH ODS), introduced the first Standard Reference Material® (SRM) for determining vitamin D metabolites in 2009 motivated by significant concerns about the comparability and accuracy of different assays to assess vitamin D status. After 14 years, a suite of five serum matrix SRMs and three calibration solution SRMs are available. Values were also assigned for vitamin D metabolites in five additional SRMs intended primarily to support measurements of other clinical diagnostic markers. Both the SRMs and the certification approach have evolved from significant exogenous serum content to primarily endogenous content and from value assignment by combining the results of multiple analytical methods to the use of measurements exclusively from reference measurement procedures (RMPs). The impact of the availability of these SRMs can be assessed by both the distribution information (sales) and by reports in the scientific literature describing their use for method validation, quality control, and research. In this review, we describe the development of these SRMs, the evolution in design and value assignment, the expansion of information reported, and SRM use in validating analytical methods and providing quality assurance within the vitamin D measurement community.