Lot-to-lot variation and verification.

Lot-to-lot verification is an integral component for monitoring the long-term stability of a measurement procedure. The practice is challenged by the resource requirements as well as uncertainty surrounding experimental design and statistical analysis that is optimal for individual laboratories, although guidance is becoming increasingly available. Collaborative verification efforts as well as application of patient-based monitoring are likely to further improve identification of any differences in performance in a relatively timely manner. Appropriate follow up actions of failed lot-to-lot verification is required and must balance potential disruptions to clinical services provided by the laboratory. Manufacturers need to increase transparency surrounding release criteria and work closer with laboratory professionals to ensure acceptable reagent lots are released to end users. A tripartite collaboration between regulatory bodies, manufacturers, and laboratory medicine professional bodies is key to developing a balanced system where regulatory, manufacturing, and clinical requirements of laboratory testing are met, to minimize differences between reagent lots and ensure patient safety. Clinical Chemistry and Laboratory Medicine has served as a fertile platform for advancing the discussion and practice of lot-to-lot verification in the past 60 years and will continue to be an advocate of this important topic for many more years to come.

Method evaluation in the clinical laboratory.

Method evaluation is one of the critical components of the quality system that ensures the ongoing quality of a clinical laboratory. As part of implementing new methods or reviewing best practices, the peer-reviewed published literature is often searched for guidance. From the outset, Clinical Chemistry and Laboratory Medicine (CCLM) has a rich history of publishing methods relevant to clinical laboratory medicine. An insight into submissions, from editors' and reviewers' experiences, shows that authors still struggle with method evaluation, particularly the appropriate requirements for validation in clinical laboratory medicine. Here, we consider through a series of discussion points an overview of the status, challenges, and needs of method evaluation from the perspective of clinical laboratory medicine. We identify six key high-level aspects of clinical laboratory method evaluation that potentially lead to inconsistency. 1. Standardisation of terminology, 2. Selection of analytical performance specifications, 3. Experimental design of method evaluation, 4. Sample requirements of method evaluation, 5. Statistical assessment and interpretation of method evaluation data, and 6. Reporting of method evaluation data. Each of these areas requires considerable work to harmonise the practice of method evaluation in laboratory medicine, including more empirical studies to be incorporated into guidance documents that are relevant to clinical laboratories and are freely and widely available. To further close the loop, educational activities and fostering professional collaborations are essential to promote and improve the practice of method evaluation procedures.

Current and emerging technologies for the timely screening and diagnosis of neonatal jaundice.

Neonatal jaundice is one of the most common clinical conditions affecting newborns. For most newborns, jaundice is harmless, however, a proportion of newborns develops severe neonatal jaundice requiring therapeutic interventions, accentuating the need to have reliable and accurate screening tools for timely recognition across different health settings. The gold standard method in diagnosing jaundice involves a blood test and requires specialized hospital-based laboratory instruments. Despite technological advancements in point-of-care laboratory medicine, there is limited accessibility of the specialized devices and sample stability in geographically remote areas. Lack of suitable testing options leads to delays in timely diagnosis and treatment of clinically significant jaundice in developed and developing countries alike. There has been an ever-increasing need for a low-cost, simple to use screening technology to improve timely diagnosis and management of neonatal jaundice. Consequently, several point-of-care (POC) devices have been developed to address this concern. This paper aims to review the literature, focusing on emerging technologies in the screening and diagnosing of neonatal jaundice. We report on the challenges associated with the existing screening tools, followed by an overview of emerging sensors currently in pre-clinical development and the emerging POC devices in clinical trials to advance the screening of neonatal jaundice. The benefits offered by emerging POC devices include their ease of use, low cost, and the accessibility of rapid response test results. However, further clinical trials are required to overcome the current limitations of the emerging POC's before their implementation in clinical settings. Hence, the need for a simple to use, low-cost POC jaundice detection technology for newborns remains an unsolved challenge globally.

Characterization and outcome of 41 patients with beta-ketothiolase deficiency: 10 years' experience of a medical center in northern Vietnam.

Beta-ketothiolase (T2) deficiency is an inherited disease of isoleucine and ketone body metabolism caused by mutations in the ACAT1 gene. Between 2005 and 2016, a total of 41 patients with T2 deficiency were identified at a medical center in northern Vietnam, with an estimated incidence of one in 190,000 newborns. Most patients manifested ketoacidotic episodes of varying severity between 6 and 18 months of age. Remarkably, 28% of patients showed high blood glucose levels (up to 23.3 mmol/L). Ketoacidotic episodes recurred in 43% of patients. The age of onset, frequency of episodes, and identified genotype did not affect patient outcomes that were generally favorable, with the exception of seven cases (five died and two had neurological sequelae). Custom-tailored acute and follow-up management was critical for a positive clinical outcome. Two null mutations, c.622C>T (p.Arg208*) and c.1006-1G>C (p.Val336fs), accounted for 66% and 19% of all identified ACAT1 mutant alleles, respectively. Most patients showed characteristic biochemical abnormalities. A newborn screening program could be expected to have a high yield in Vietnam. Investigation findings of haplotypes linked to the most common ACAT1 mutation (c.622C>T) are consistent with an ancient common founder of mutation-bearing chromosomes belonging to the Kinh ethnic population. The direct management and long-term follow-up of a large number of T2-deficient patients enabled us to study the natural history of this rare disease.

Practical application of biological variation and Sigma metrics quality models to evaluate 20 chemistry analytes on the Beckman Coulter AU680.

OBJECTIVES: This study aimed to evaluate the imprecision and bias data generated for 20 routine chemistry analytes against both the biological variation fitness for purpose (FFP) and Sigma metrics (SM) criteria. DESIGN AND METHOD: Twenty serum/plasma analytes were evaluated on the Beckman Coulter AU680. Third party commercial lyophilized internal quality control samples of human origin were used for day-to-day imprecision calculations. Commercial external quality assurance (EQA) samples were used to determine the systematic error between the test method result and the instrument group mean result from the EQA program for each analyte. Biological variation data was used to calculate the minimum, desirable and optimal imprecision and bias for determination of FFP. The desirable total allowable error was determined from biological variation data and applied to the SM calculation. The outcomes of both quality approaches were then compared. RESULTS: The day-to-day imprecision of most tested analytes (except sodium and chloride) were smaller than the allowable imprecision (ranging from minimum to optimum). Most analytes achieved at least minimum bias. The SM varied with analyte concentration with six analytes producing low Sigma values. Comparing the quality processes eleven analytes produced a green light for both FFP and SM. There was some difference seen in interpretation for the other nine analytes. CONCLUSIONS: The individual interpretation of bias and imprecision using FFP criteria allowed for the clear determination of the major source of error. Whereas, SM provided a summative evaluation of method performance. But the selection of total allowable error (TEa) is fundamental to this interpretation and harmonisation of the TEa calculation is needed.

Development of a new biochemical test to diagnose and monitor neuroblastoma in Vietnam: homovanillic and vanillylmandelic acid by gas chromatography-mass spectrometry.

OBJECTIVES: The aim of this study was to develop an accurate robust testing method to simultaneously measure urine levels of HVA and VMA using gas chromatography mass spectrometry (GCMS) and to establish age-specific reference intervals of HVA and VMA in random urines for Vietnamese children. DESIGN AND METHODS: The assay for urinary HVA and VMA was developed based on a classical urinary organic acid profiling method. Briefly, this incorporated 3-phenyl butyric acid as the internal standard and liquid-liquid extraction with ethyl acetate followed by derivatization with BSTFA. The Agilent 7890A GC and 5975C Mass Selective Detector in single ion monitoring mode was used for analysis. Reference intervals were developed from random urine samples collected from 634 disease free Vietnamese children and compared to 50 known neuroblastoma patient samples. Results were reported relative to creatinine concentration. Age related 95% reference intervals for urinary HVA and VMA were estimated from sample quantiles. The analytes (expressed as analyte/creatinine ratios) diagnostic values were determined by calculating the related sensitivity, specificity and likelihood ratios. RESULTS: HVA and VMA were linear to at least 193 and 221µmol/L, respectively. The limit of quantitation for both analytes was 0.9µmol/L. Using the bi-level control (n=15), the within-batch coefficients of variations (CVs) were less than 3% for both analytes across the assay range. The between-batch CVs (n=20 over three months), were 3.6% at 11µmol/L and 2.1% at 88µmol/L for HVA, 6.6% at 18.2µmol/L and 2.6% at 90.6µmol/L for VMA. Vietnamese age related reference intervals were established for urinary HVA and VMA per creatinine. HVA for children <6months (n=91) was 5.3-37.0µmol/mmol; 6months to <1year (n=141) was 2.7-27.7µmol/mmol; 1 to 5years (n=139) was 3.4-17.9µmol/mmol; 6 to 10years (n=136) was 2.7-8.8µmol/mmol; and 11 to 15years (n=127) was 1.1-9.4µmol/mmol. VMA for children <6months was 1.8-12.2µmol/mmol; 6months to <1year was 1.5-9.3µmol/mmol; 1 to 5years was 1.9-7.8µmol/mmol; 6 to 10years was 1.6-5.1µmol/mmol; and 11 to 15years was <0.9-6.3µmol/mmol. CONCLUSIONS: A robust testing method for simultaneous quantitation of urinary HVA and VMA by GCMS was developed. This method is accurate, precise and fit for its clinical purpose and suitable for developing countries. Age-related reference intervals of urinary HVA and VMA were established for Vietnamese children and the intervals declined progressively with increasing age for each analyte.