UNASSIGNED: Procalcitonin (PCT) is a useful biomarker in the initial evaluation of febrile infants for serious bacterial infections (SBIs). However, PCT is not always available locally and must at times be frozen and shipped to a reference laboratory for research studies. We sought to compare PCT measured locally versus centrally at a reference laboratory during a research study.
UNASSIGNED: This was a secondary analysis of a multicenter study of febrile infants ≤60 days evaluated for SBIs from June 2016 to April 2019. A PCT cutoff value of 0.5 ng/mL was used to stratify infants at low-versus high-risk of SBIs. Statistical analyses consisted of Spearman\'s correlation, Bland-Altman difference plotting, Passing-Bablok regression, Deming regression, and Fisher\'s exact testing at the 0.5 ng/mL threshold.
UNASSIGNED: 241 febrile infants had PCT levels measured both locally and at the reference laboratory. PCT levels measured locally on 5 different platforms and from the frozen research samples demonstrated strong Spearman\'s correlation (ρ = 0.83) and had similar mean PCT values with an average relative difference of 0.02%. Eleven infants with SBIs had PCT values < 0.5 ng/mL in both the clinical and research samples. Six other infants had differences in SBI prediction based on PCT values at the 0.5 ng/mL threshold between the clinical and research platforms.
UNASSIGNED: We found no significant differences in detection of febrile infants at high risk for SBI based on locally (on multiple platforms) versus centrally processed PCT. Testing at a central reference laboratory after freezing and shipping is an accurate and reliable alternative for research studies or when rapid turnaround is not required.

Newborn screening (NBS) laboratories in the United Kingdom adhere to common protocols based on single analyte cutoff values (COVs); therefore, interlaboratory harmonization is of paramount importance. Interlaboratory variation for screening analytes in UK NBS laboratories ranges from 17% to 59%. While using common stable isotope internal standards has been shown to significantly reduce interlaboratory variation, instrument set-up, sample extraction, and calibration approach are also key factors.
Dried blood spot (DBS) extraction processes, instrument set-up, mobile-phase composition, sample introduction technique, and calibration approach of flow injection analysis-tandem mass spectrometry (FIA-MS/MS) methods were optimized. Inter- and intralaboratory variation of methionine, leucine, phenylalanine, tyrosine, isovaleryl-carnitine, glutaryl-carnitine, octanoyl-carnitine, and decanoyl-carnitine were determined pre- and postoptimization, using 3 different calibration approaches.
Optimal recovery of analytes from DBS was achieved with a 35-min extraction time and 80% methanol (150 μL). Optimized methodology decreased the mean intralaboratory percentage relative SD (%RSD) for the 8 analytes from 20.7% (range 4.1-46.0) to 5.4% (range 3.0-8.5). The alternative calibration approach reduced the mean interlaboratory %RSD for all analytes from 16.8% (range 4.1-25.0) to 7.1% (range 4.1-11.0). Nuclear magnetic resonance analysis of the calibration material highlighted the need for standardization. The purities of isovaleryl-carnitine and glutaryl-carnitine were 85.13% and 69.94% respectively, below the manufacturer\'s stated values of ≥98%.
For NBS programs provided by multiple laboratories using single analyte COVs, harmonization and standardization of results can be achieved by optimizing legacy FIA-MS/MS methods, adopting a common analytical protocol, and using standardized calibration material rather than internal calibration.

Vitamin D is an important fat-soluble prohormone with pleiotropic effects on human health, such as immunomodulation of the innate and adaptive immune system. There is an unmet clinical need for a rapid screening platform for 25-hydroxyvitamin D (25OH-D) determination without chromatographic separation that offers better precision and accuracy than immunoassays. Here, we introduce a high-throughput method for assessing vitamin D status from blood specimens based on direct infusion-MS/MS (DI-MS/MS) following click derivatization using 2-nitrosopyridine. We developed an optimized liquid-phase extraction protocol to minimize ion suppression when directly infusing serum or plasma extracts via a capillary electrophoresis system for quantitative determination of 25OH-D. Acceptable reproducibility (mean coefficient of variation = 10.9%, n = 412), recovery (mean = 102% at 15, 30, and 45 nmol/l), and linearity (R2 > 0.998) were achieved for 25OH-D with lower detection limits (limit of detection ∼1.2 nmol/l, S/N ∼ 3), greater throughput (∼3 min/sample), and less bias than a commercial chemiluminescence immunoassay prone to batch effects. There was mutual agreement in 25OH-D concentrations from reference blood samples measured by DI-MS/MS as compared with LC-MS/MS (mean bias = 7.8%, n = 18). We also demonstrate that this method could reduce immunoassay misclassification of vitamin D deficiency in a cohort of critically ill children (n = 30). In conclusion, DI-MS/MS offers a viable alternative to LC-MS/MS for assessment of vitamin D status in support of large-scale studies in nutritional epidemiology as well as clinical trials to rapidly screen individual patients who may benefit from vitamin D supplementation.

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BACKGROUND: An evolving COVID-19 testing landscape and issues with test supply allocation, especially in the current pandemic, has made it challenging for ordering providers. We audited orders of the Xpert® Xpress SARS-CoV-2 PCR with reverse transcription (RT-PCR) platform-the fastest of several other testing modalities available-to illuminate these challenges utilizing a multidisciplinary laboratory professional team consisting of a pathology resident and microbiology laboratory director.
METHODS: Retrospective review of the first 5 hundred Xpert Xpress SARS-CoV-2 RT-PCR test orders from a 2-week period to determine test appropriateness based on the following indications: emergency surgery, emergent obstetric procedures, initial behavioral health admission, and later including discharge to skilled care facilities and pediatric admissions. Our hypothesis was that a significant proportion of orders for this testing platform were inappropriate.
RESULTS: On review, a significant proportion of orders were incorrect, with 69.8% (n = 349, P < 0.0001) not meeting indications for rapid testing. Of all orders, 249 designated as emergency surgery were inappropriate, with 49.0% of those orders never proceeding with any surgical intervention; most of these were trauma related (64.6% were orders associated with a trauma unit).
CONCLUSIONS: Significant, pervasive inappropriate ordering practices were identified at this center. A laboratory professional team can be key to identifying problems in testing and play a significant role in combating inappropriate test utilization.