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Context.--Paraprotein interference in automated chemistry is uncommon. We describe 2 patients with paraproteinemia and elevated total bilirubin levels measured erroneously using the Roche total bilirubin assay. Objectives.--To explain the mechanism of this artifactual hyperbilirubinemia and to determine its frequency in patients with monoclonal or increased immunoglobulins. Materials and Methods.--The assay was performed manually using serum from 2 index patients and from control patients (without M proteins). Total bilirubin was also determined using another manufacturer's assay. A prospective study was then undertaken using serum from 100 consecutive patients with various monoclonal gammopathies and from 13 patients with polyclonal hypergammaglobulinemia and cryoglobulins. For all patients, serum immunoglobulin (Ig), G, IgA, IgM, total and direct bilirubin, creatinine, and a direct spectrophotometric assessment of icterus were measured. Results.--After the addition of assay reagents, a white precipitate formed in the reaction mixtures containing serum from the index patients, but not in other samples. This turbidity, rather than the expected color change to pink, increased the absorbance and falsely elevated the total bilirubin value. Serum from both index patients was anicteric, their direct bilirubin measurements were unaffected, and total bilirubin measured using an alternate assay was normal. Among the 113 patients studied, no additional spurious total bilirubin values were detected. Conclusion.--Paraprotein interference with the Roche automated total bilirubin assay is caused by precipitate formation. This interference is rare and probably idiosyncratic. Spurious hyperbilirubinemia from paraprotein interference may cause clinical confusion. If artifactual elevation of total bilirubin is suspected, the laboratory should examine the specimen for icterus (manually or by spectrophotometry) or measure total bilirubin using a different method. [ABSTRACT FROM AUTHOR]

Laboratories faced many challenges throughout the COVID-19 pandemic. Point-of-care (POC) SARS-CoV-2 nucleic acid amplification tests (NAATs) provided a key solution to the need for rapid turnaround time in select patient populations and were implemented at the POC but also within laboratories to supplement traditional molecular assays. Clinical Laboratory Improvement Amendments-waived rapid POC SARS-CoV-2 NAATs offer the benefit of reduced educational requirements for operators and can be performed by non-laboratory-trained individuals. However, these methods must be validated to ensure the manufacturer's performance specifications are met and they are found to be fit-for-purpose in the clinical workflows they are implemented., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Recognizing that race is a social and not a biological construct, healthcare professionals and the public have called for removal of race in clinical algorithms. In response, the National Kidney Foundation and the American Society of Nephrology created the Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Diseases to examine the issue and provide recommendations. The final report from the Task Force recommends calculating estimated glomerular filtration rate (eGFR) without a race coefficient using the recently published CKD-EPI 2021 creatinine (cr) and creatinine-cystatin C (cr-cys) equations. The Task Force recommends immediately replacing older eGFRcr equations (MDRD Study and CKD-EPI 2009) with the new CKD-EPI 2021 equation. In a 2019 survey by the College of American Pathologists, 23% of 6200 laboratories reporting eGFRcr used an incorrect equation that is not suitable for use with standardized creatinine measurements, 34% used the CKD-EPI 2009 equation and 43% used the MDRD Study 2006 equation re-expressed for standardized creatinine measurement. Rapid transition to using the CKD-EPI 2021 equation is an opportunity for laboratories to standardize to a single equation to eliminate differences in eGFRcr due to different equations used by different laboratories, and to report eGFR without use of race. We provide guidance to laboratories for implementing the CKD-EPI 2021 equations for both eGFRcr and eGFRcr-cys., (© American Association for Clinical Chemistry 2022.)

Bacterial infections are one of the major causes of death worldwide. The identification of a bacterial species that is the source of an infection generally takes a long time, and often exceeds the treatment window for seriously ill patients. Many of these deaths are preventable if the bacterial species can be identified quickly. Here we present an optical spectroscopic method for rapid detection and identification of bacteria directly from whole blood using a light scattering spectroscopy technique. This technique was originally developed to detect pre-cancerous changes in epithelial tissues, characterize changes in tissue on the cellular scale, and characterize biological structures comparable to or smaller than a single wavelength. We demonstrate here that not only can an inexpensive light scattering spectroscopy-based biosensor rapidly detect and identify four bacteria species in the blood, responsible for the majority of death causing infections, but that species-level identification can potentially be made based on approximately one thousand bacterial cells per milliliter of blood. Observing entire colonies or performing susceptibility testing is therefore not required., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest. Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Background: Detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by reverse transcription PCR is the primary method to diagnose coronavirus disease 2019 (COVID-19). However, the analytic sensitivity required is not well defined and it is unclear how available assays compare., Methods: For the Abbott RealTime SARS-CoV-2 assay (m2000; Abbott Molecular), we determined that it could detect viral concentrations as low as 26 copies/mL, we defined the relationship between cycle number and viral concentrations, and we tested naso- and oropharyngeal swab specimens from 8538 consecutive individuals. Using the m2000 as a reference assay method, we described the distribution of viral concentrations in these patients. We then used selected clinical specimens to determine the positive percent agreement of 2 other assays with more rapid turnaround times [Cepheid Xpert Xpress (GeneXpert; Cepheid); n = 27] and a laboratory developed test on the Luminex ARIES system [ARIES LDT (Luminex); n = 50] as a function of virus concentrations, from which we projected their false-negative rates in our patient population., Results: SARS-CoV-2 was detected in 27% (95% CI: 26%-28%) of all specimens. Estimated viral concentrations were widely distributed, and 17% (95% CI: 16%-19%) of positive individuals had viral concentrations <845 copies/mL. Positive percent agreement was strongly related to viral concentration, and reliable detection (i.e., ≥95%) was observed at concentrations >100 copies/mL for the GeneXpert but not the ARIES LDT, corresponding to projected false-negative rates of 4% (95% CI: 0%-21%) and 27% (95% CI: 11%-46%), respectively., Conclusions: Substantial proportions of clinical specimens have low to moderate viral concentrations and may be missed by methods with less analytic sensitivity., (© American Association for Clinical Chemistry 2020. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Importance: Laboratory data are frequently collected throughout the care of critically ill patients. Currently, these data are interpreted by comparison with values from healthy outpatient volunteers. Whether this is the most useful comparison has yet to be demonstrated., Objectives: To understand how the distribution of intensive care unit (ICU) laboratory values differs from the reference range, and how these distributions are related to patient outcomes., Design, Setting, and Participants: Cross-sectional study of a large critical care database, the Medical Information Mart for Intensive Care database, from January 1, 2001, to October 31, 2012. The database is collected from ICU data from a large tertiary medical center in Boston, Massachusetts. The data are collected from medical, cardiac, neurologic, and surgical ICUs. All patients in the database from all ICUs for 2001 to 2012 were included. Common laboratory measurements over the time window of interest were sampled. The analysis was conducted from March to June 2017., Main Outcomes and Measures: The overlapping coefficient and Cohen standardized mean difference between distributions were calculated, and kernel density estimate visualizations for the association between laboratory values and the probability of death or quartile of ICU length of stay were created., Results: Among 38 605 patients in the ICU (21 852 [56.6%] male; mean [SD] age, 74.5 [55.1] years), 8878 (23%) had the best outcome (ICU survival, shortest quartile length of stay) and 3090 (8%) had the worst outcome (ICU nonsurvival). Distribution curves based on ICU data differed significantly from the hospital standard range (mean [SD] overlapping coefficient, 0.51 [0.32-0.69]). All laboratory values for the best outcome group differed significantly from those in the worst outcome group. Both the best and worst outcome group curves revealed little overlap with and marked divergence from the reference range., Conclusions and Relevance: The standard reference ranges obtained from healthy volunteers differ from the analogous range generated from data from patients in intensive care. Laboratory data interpretation may benefit from greater consideration of clinically contextual and outcomes-related factors.

The enormous increase of Raman signal in the vicinity of metal nanoparticles allows surface-enhanced Raman spectroscopy (SERS) to be employed for label-free detection of substances at extremely low concentrations. However, the ultimate potential of label-free SERS to identify pharmaceutical compounds at low concentrations, especially in relation to biofluid sensing, is far from being fully realized. Opioids are a particular challenge for rapid clinical identification because their molecular structural similarities prevent their differentiation with immunolabeling approaches. In this paper, a new method called quantitative label-free SERS (QLF-SERS) which involves the formation of halide-conjugated gold nanoclusters trapping the analyte of interest near the SERS hot spots is reported, and it is demonstrated that it yields a 10 5 fold improvement in the detection limit over previously reported results for the entire class of clinically relevant opioids and their metabolites. Measurements of opioid concentrations in multicomponent mixtures are also demonstrated. QLF-SERS has comparable detection limits as currently existing laboratory urine drug testing techniques but is significantly faster and inexpensive and, therefore, can be easily adapted as part of a rapid clinical laboratory routine., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Glycated hemoglobin, HbA1c, is an important biomarker that reveals the average value of blood glucose over the preceding 3 months. While significant recent attention has been focused on the use of optical and direct molecular spectroscopic methods for determination of HbA1c, a facile test that minimizes sample preparation needs and turnaround time still remains elusive. Here, we report a label-free approach for identifying low, mid and high-HbA1c groups in hemolysate and in whole blood samples featuring resonance Raman (RR) spectroscopy and support vector machine (SVM)-based classification of spectral patterns. The diagnostic power of RR measurements stems from its selective enhancement of hemoglobin-specific features, which simultaneously minimizes the blood matrix spectral interference and permits detection in the native solution. In this pilot study, our spectroscopic observations reveal that glycation of hemoglobin results in subtle but reproducible changes even when detected in the whole blood matrix. Leveraging SVM analysis of the principal component scores determined from the RR spectra, we show high degree of accuracy in classifying clinical specimen. We envisage that the promising findings will pave the way for more extensive clinical specimen investigations with the ultimate goal of translating molecular spectroscopy for routine point-of-care testing., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: With a 10-year sustained increase in 25-hydroxyvitamin D [25(OH)D] testing, laboratories have swapped their LC-MS/MS methods for high-throughput automated immunoassays. Although it is generally well-known that immunoassays have poor recoveries for 25-hydroxyvitamin D2 [25(OH)D2], the frequency and extent to which this impacts total 25(OH)D have not been previously demonstrated. We evaluated 3 automated immunoassays against the first FDA-cleared CDC/NIST-traceable LC-MS/MS method., Methods: Method comparison was performed for the Siemens ADVIA Centaur, Roche Elecsys Cobas, and Abbott Architect 25(OH)D immunoassay methods in real patient samples (n = 105). We calculated the mean bias in samples containing >20 ng/mL 25(OH)D2 and estimated the percent 25(OH)D2 cross-reactivities. We determined the prevalence of appreciable concentrations of 25(OH)D2 in our patient population through random sampling (n = 120) and projected the frequency of inaccurate 25(OH)D immunoassay results., Results: Linear regression for 25(OH)D was y = 1.09x - 4.44 (Centaur), y = 0.84 + 0.43 (Cobas), and y = 0.83x - 0.48 (Architect). The mean biases of 25(OH)D concentrations were 5.6 (11.0) ng/mL (Centaur), -17.5 (7.2) ng/mL (Cobas), and -20.3 (9.8) ng/mL (Architect) in samples containing >20 ng/mL 25(OH)D2. The observed percent cross-reactivities for 25(OH)D2 were 115% (Centaur), 52% (Cobas), and 44% (Architect). We estimate that 8% of our population has >20 ng/mL 25(OH)D2, thereby compromising the accuracy of 25(OH)D results in >3000 samples annually., Conclusions: We demonstrate that immunoassay manufacturer package inserts indicate much better recoveries of 25(OH)D2 than what is observed in unadulterated real patient samples. We estimate the frequency of inaccurate total 25(OH)D determination by these immunoassay methods to be largely dependent on the concentration of 25(OH)D2 in each sample., (© 2017 American Association for Clinical Chemistry.)

Context: Hemolysis is an important clinical laboratory quality attribute that influences result reliability., Objective: To determine hemolysis identification and rejection practices occurring in clinical laboratories., Design: We used the College of American Pathologists Survey program to distribute a Q-Probes-type questionnaire about hemolysis practices to Chemistry Survey participants., Results: Of 3495 participants sent the questionnaire, 846 (24%) responded. In 71% of 772 laboratories, the hemolysis rate was less than 3.0%, whereas in 5%, it was 6.0% or greater. A visual scale, an instrument scale, and combination of visual and instrument scales were used to identify hemolysis in 48%, 11%, and 41% of laboratories, respectively. A picture of the hemolysis level was used as an aid to technologists' visual interpretation of hemolysis levels in 40% of laboratories. In 7.0% of laboratories, all hemolyzed specimens were rejected; in 4% of laboratories, no hemolyzed specimens were rejected; and in 88% of laboratories, some specimens were rejected depending on hemolysis levels. Participants used 69 different terms to describe hemolysis scales, with 21 terms used in more than 10 laboratories. Slight and moderate were the terms used most commonly. Of 16 different cutoffs used to reject hemolyzed specimens, moderate was the most common, occurring in 30% of laboratories. For whole blood electrolyte measurements performed in 86 laboratories, 57% did not evaluate the presence of hemolysis, but for those that did, the most common practice in 21 laboratories (24%) was centrifuging and visually determining the presence of hemolysis in all specimens., Conclusions: Hemolysis practices vary widely. Standard assessment and consistent reporting are the first steps in reducing interlaboratory variability among results.

Context: Hemolyzed specimens delay clinical laboratory results, proliferate unnecessary testing, complicate physician decisions, injure patients indirectly, and increase health care costs., Objective: To determine quality improvement practices when hemolysis occurs., Design: We used the College of American Pathologists (CAP) Survey Program to distribute a Q-Probes-type questionnaire about hemolysis practices to CAP Chemistry Survey participants., Results: Of 3495 participants sent the questionnaire, 846 (24%) responded. Although 85%, 69%, and 55% of participants had written hemolysis policies for potassium, lactate dehydrogenase, and glucose, respectively, only a few (46%, 40%, and 40%) had standardized hemolysis reports between their primary and secondary chemistry analyzers for these 3 analytes. Most participants (70%) had not attempted to validate the manufacturers' hemolysis data for these 3 analytes; however, essentially all who tried, succeeded. Forty-nine percent of participants had taken corrective action to reduce hemolysis during the past year and used, on average, 2.4 different actions, with collection and distribution of hemolysis data to administrative leadership (57%), troubleshooting outliers (55%), retraining phlebotomist (53%), and establishment of quality improvement teams among the laboratory and at problem locations (37%) being the most common actions. When asked to assess their progress in reducing hemolysis, 70% noted slow to no progress, and 2% gave up on improvement. Upon measuring potassium, lactate dehydrogenase, and glucose, approximately 60% of participants used the same specimen flag for hemolysis as for lipemia and icterus., Conclusions: Hemolysis decreases the quality and increases the cost of health care. Practices for measuring, reporting, and decreasing hemolysis rates need improvement.

In the past decade, considerable attention has been focused on the measurement of glycemic markers, such as glycated hemoglobin and glycated albumin, that provide retrospective indices of average glucose levels in the bloodstream. While these biomarkers have been regularly used to monitor long-term glucose control in established diabetics, they have also gained traction in diabetic screening. Detection of such glycemic markers is challenging, especially in a point-of-care setting, due to the stringent requirements for sensitivity and robustness. A number of non-separation based measurement strategies were recently proposed, including photonic tools that are well suited to reagent-free marker quantitation. Here, we critically review these methods while focusing on vibrational spectroscopic methods, which offer highly specific molecular fingerprinting capability. We examine the underlying principles and the utility of these approaches as reagentless assays capable of multiplexed detection of glycemic markers and also the challenges in their eventual use in the clinic.

Results of therapeutic monitoring of sirolimus blood concentrations are assay and laboratory dependent. This study compared performance over time of the IMx microparticle enzyme immunoassay (MEIA), Architect chemiluminescent microparticle immunoassay (CMIA), and liquid chromatography with mass spectrometric detection (LC/MS/MS) as part of a proficiency testing scheme. Pooled samples from sirolimus-treated patients and whole-blood samples spiked with known quantities of sirolimus were assayed monthly between 2004 and 2012. When results of pooled patient samples were compared with LC/MS/MS, the MEIA assay showed an overall mean percent bias of -2.3% ± 11.2% that, although initially positive, became increasingly negative from 2007 through 2009. The CMIA, which replaced the MEIA assay, had a mean percent bias of 21.9% ± 12.3%, remaining stable from 2007 through 2012. Similarly, for spiked samples, the MEIA showed an increasingly negative bias over time vs. LC/MS/MS, whereas CMIA maintained a stable positive bias. Based on comparison of immunoassay measurements on individual patient samples, CMIA values were more than 25% higher than MEIA values. These results highlight the importance of continued proficiency testing and regular monitoring of sirolimus assay performance. Clinicians must be aware of the methodology used and adjust target levels accordingly to avoid potential effects on efficacy and toxicity., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: To assess whether glycemic control, soluble fms-like tyrosine kinase 1 (sFlt1) and placental growth factor (PlGF) were associated with the development of preeclampsia (PE) or gestational hypertension (GHTN) in women with preexisting diabetes., Methods: Maternal circulating angiogenic factors (sFlt1 and PlGF) measured on automated platform were studied at four time points during pregnancy in women with diabetes (N = 159) and reported as multiples of the median (MOM) of sFlt1/PlGF ratio (median, 25th-75th percentile) noted in non-diabetic non-hypertensive control pregnant population (N = 139). Diagnosis of PE or GHTN was determined by review of de-identified clinical data., Results: PE developed in 12% (N = 19) and GHTN developed in 23% (N = 37) of the women with diabetes. Among diabetic women without PE or GHTN, median sFlt1/PlGF levels at 35-40 weeks was threefold higher than in non-diabetic controls [MOM 3.21(1.19-7.24), p = 0.0001]. Diabetic women who subsequently developed PE had even greater alterations in sFlt1/PlGF ratio during the third trimester [MOM for PE at 27-34 weeks 15.18 (2.37-26.86), at 35-40 weeks 8.61(1.20-18.27), p ≤ 0.01 for both windows compared to non-diabetic controls]. Women with diabetes who subsequently developed GHTN also had significant alterations in angiogenic factors during third trimester; however, these findings were less striking. Among women with diabetes, glycosylated hemoglobin (HbA1c) during the first trimester was higher in subjects who subsequently developed PE (7.7 vs 6.7%, p = 0.0001 for diabetic PE vs diabetic non-PE)., Conclusions: Women with diabetes had a markedly altered anti-angiogenic state late in pregnancy that was further exacerbated in subjects who developed PE. Altered angiogenic factors may be one mechanism for the increased risk of PE in this population. Increased HbA1c in the first trimester of pregnancies in women with diabetes was strongly associated with subsequent PE.

Background: Serum folate levels are commonly ordered for multiple indications in the inpatient and emergency department settings. Since mandatory folic acid fortification in 1998, there has been a decreasing prevalence of folate deficiency in the United States., Objective: Our objective was to determine the indications, rate of deficiency, charge and cost per deficient result, and change in management per deficient result in serum folate testing in inpatients and emergency department patients., Design: Retrospective analysis of all inpatient and emergency department serum folate tests., Methods: We analyzed all inpatient and emergency department serum folate tests performed over a 12-month period. We reviewed the charts of 250 patients and all low-normal or deficient serum folate levels to determine indications, comorbidities, and change in management based on result. Charge and cost analyses were performed., Setting/patients: All inpatient and emergency department patients with a serum folate test performed at a major medical center in Boston, Massachusetts., Results: A total of 2093 serum folate tests were performed in 1944 patients with 2 deficient levels. The most common indications were anemia without macrocytosis and anemia with macrocytosis. The amount charged per deficient result was $158,022. The cost to the hospital per deficient result was less than $2093., Conclusions: In folic acid fortified countries, serum folate testing has low utility and poor cost effectiveness for all indications in inpatients and emergency department patients., (Copyright © 2012 Society of Hospital Medicine.)

Objectives: The objective of this study is to determine whether creatine kinase-MB (CK-MB) index (CK-MBi) is useful in the evaluation of acute myocardial infarction (AMI) in patients with indeterminate troponin (Tn) in the emergency department (ED)., Methods: A retrospective cohort study was conducted of patients at an urban academic ED with over 55 000 annual visits who underwent Tn T (Roche, Indianapolis, IN) and CK-MB testing. One year of ED patients who had Tn testing were identified, and their corresponding CK-MBi was examined to find patients with indeterminate Tn (0.01-0.09) and positive CK-MBi (>6.0). Subsequent cardiac enzymes and hospital course were reviewed to identify patients diagnosed with AMI. A 95% confidence interval around point estimates were used in data analysis., Results: Over 1 year, 11 718 initial Tn were identified. Indeterminate Tn was seen in 2512 cases. Of these, 28 had positive CK-MBi. Of the 28, 5 were judged by treating physicians to be having AMI and underwent cardiac catheterization. Of the 5 patients, 4 had subsequent positive Tns on serial enzyme testing. One of the patients thought to be having AMI had no coronary artery disease on catheterization. The rate of true positive CK-MBi with indeterminate Tn was 0.16% (95% confidence interval, 0.04%-0.41%)., Conclusion: Initial results identify rare cases of AMI where CK-MBi is positive in the setting of indeterminate Tn. However, most patients with indeterminate Tn and positive CK-MBi were not judged to be having AMI. In most cases, CK-MBi is not positive with indeterminate Tn and when positive more commonly confuses the picture. This suggests CK-MBi could be eliminated in patients with indeterminate Tns., (Copyright © 2012 Elsevier Inc. All rights reserved.)

In recent years, glycated hemoglobin (HbA1c) has been increasingly accepted as a functional metric of mean blood glucose in the treatment of diabetic patients. Importantly, HbA1c provides an alternate measure of total glycemic exposure due to the representation of blood glucose throughout the day, including post-prandially. In this article, we propose and demonstrate the potential of Raman spectroscopy as a novel analytical method for quantitative detection of HbA1c, without using external dyes or reagents. Using the drop coating deposition Raman (DCDR) technique, we observe that the nonenzymatic glycosylation (glycation) of the hemoglobin molecule results in subtle but discernible and highly reproducible changes in the acquired spectra, which enable the accurate determination of glycated and nonglycated hemoglobin using standard chemometric methods. The acquired Raman spectra display excellent reproducibility of spectral characteristics at different locations in the drop and show a linear dependence of the spectral intensity on the analyte concentration. Furthermore, in hemolysate models, the developed multivariate calibration models for HbA1c show a high degree of prediction accuracy and precision--with a limit of detection that is a factor of ~15 smaller than the lowest physiological concentrations encountered in clinical practice. The excellent accuracy and reproducibility achieved in this proof-of-concept study opens substantive avenues for characterization and quantification of the glycosylation status of (therapeutic) proteins, which are widely used for biopharmaceutical development. We also envision that the proposed approach can provide a powerful tool for high-throughput HbA1c sensing in multicomponent mixtures and potentially in hemolysate and whole blood lysate samples.

Objective: To test utility of cystatin-C as a marker of glomerular filtration rate during pregnancy, we performed serial correlations with inulin clearance during pregnancy and postpartum., Methods: Twelve subjects received inulin infusions and serum cystatin-C at three time points. Pearson's correlation coefficient was calculated., Results: Cystatin-C levels ranged 0.66-1.48 mg/L during pregnancy, and 0.72-1.26 mg/L postpartum. Inulin clearance ranged 130-188 mL/min during pregnancy, and 110-167 mL/min postpartum. Cystatin-C did not correlate with inulin clearance at any time point., Conclusion: Serum cystatin-C did not correlate with inulin clearance during pregnancy or postpartum.

Objective: The aim of this study was to determine whether current troponin assay alone can be used for initial screening for acute myocardial infarction (AMI) and whether creatine kinase-MB (CK-MB) can safely be eliminated from this evaluation in the emergency department (ED)., Methods: A retrospective cohort study of patients who had cardiac troponin T (Roche, Basel, Switzerland) and CK-MB ordered at an urban academic level 1 trauma center with more than 55,000 annual visits. Patients with troponin testing in the ED were identified over a period of 12 months, and corresponding CK-MB indexes were examined identifying patients with negative troponins (<0.01) and positive CK-MB indexes (>6.0). In these patients, further cardiac markers, hospital course, and 30-day mortality were then evaluated. A 99% confidence interval around point estimate was used in data analysis., Results: During the study period, there were 11,092 separate ED patient encounters where a patient had at least one troponin resulted. Most (97.9%) of the samples had an associated CK-MB ordered. There were 7545 initial negative troponins representing 68% of all initial samples. Seven of these had an associated positive MB index. When subsequent troponins were evaluated, an additional 4910 negative troponins were identified, with 4 patients having a positive MB. None of these 11 patients were judged to have ruled in for AMI by the treating physicians. The rate of true-positive CK-MB index with negative troponin was 0% (99% confidence interval, 0-0.04%)., Conclusion: Our results suggest that CK-MB is not necessary in the initial screening for AMI and may safely be omitted in patients with negative troponins., (Copyright © 2012 Elsevier Inc. All rights reserved.)

We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future.

Background: Proficiency testing (PT), or external quality assessment (EQA), is intended to verify on a recurring basis that laboratory results conform to expectations for the quality required for patient care., Content: Key factors for interpreting PT/EQA results are knowledge of the commutability of the samples used and the process used for target value assignment. A commutable PT/EQA sample demonstrates the same numeric relationship between different measurement procedures as that expected for patients' samples. Noncommutable PT/EQA samples frequently have a matrix-related bias of unknown magnitude that limits interpretation of results. PT/EQA results for commutable samples can be used to assess accuracy against a reference measurement procedure or a designated comparison method. In addition, the agreement of the results between different measurement procedures for commutable samples reflects that which would be seen for patients' samples. PT/EQA results for noncommutable samples must be compared to a peer group mean/median of results from participants who use measurement procedures that are expected to have the same or very similar matrix-related bias. Peer group evaluation is used to asses whether a laboratory is using a measurement procedure in conformance to the manufacturer's specifications and/or in conformance to other laboratories using the same technology. A noncommutable PT/EQA sample does not give meaningful information about the relationship of results for patients' samples between different measurement procedures., Summary: PT/EQA provides substantial value to the practice of laboratory medicine by assessing the performance of individual laboratories and, when commutable samples are used, the status of standardization or harmonization among different measurement procedures.

Ethylene glycol ingestion, accidental or intentional, can be a life-threatening emergency. Assays are not available from most clinical laboratories, and, thus, results often require many hours or days to obtain. Enzymatic assays, adaptable to automated chemistry analyzers, have been evaluated, but they have been plagued by analytic problems. With an alternative method of data analysis applied to an existing enzymatic assay, a modified assay was developed and validated on 2 different automated chemistry systems. Compared with a previously validated method based on gas chromatography with flame ionization detection, the modified enzymatic assay showed excellent agreement on patient samples (y = 1.0227x -1.24; r(2) = 0.9725), with a large analytic measuring range (2.5-300 mg/dL [0.4-48.4 mmol/L]). Interferences from propylene glycol, various butanediols, and other related compounds were almost entirely eliminated; when present, they generated error flags rather than falsely elevated ethylene glycol results. This modified assay should make it possible for more clinical laboratories to offer ethylene glycol measurements.

Context: Light chain disease represents 15% to 20% of cases of multiple myeloma. Current guidelines recommend monitoring these patients with 24-hour urine collections., Objective: To determine the reliability of 24-hour urine collections in assessing the amount of Bence-Jones protein (BJP)., Design: We included all patients from our institution from 2003 through 2008 with BJP who had more than four 24-hour urine collections. We compared BJP excretion calculated from the submitted 24-hour collection with BJP excretion calculated by normalizing the collection to that patient's mean 24-hour creatinine excretion. We also looked at differences in serial values with these 2 methods. In addition, we evaluated the feasibility of using random urine samples to determine BJP excretion., Results: A total of 14 patients with 135 24-hour urine collections met our inclusion criteria. The 24-hour urine creatinine excretion for each patient, which should be reasonably constant, varied considerably (coefficient of variation range 12%-30%). Differences in the 2 methods of calculating BJP excretion ranged from -1588 to 2315 mg/d. Among a total of 121 serial 24-hour measurements, the differences were clinically significant in 37 (30%). Among a total of 23 random urine samples from 11 of these patients submitted within 10 days of a 24-hour collection, the estimated BJP excretion appeared to be accurate in at least 18 (78%)., Conclusions: Twenty-four-hour urine collections for BJP are, in practice, often misleading. At a minimum, one should verify that the 24-hour creatinine excretion is accurate. In addition, it may be possible to use the protein/creatinine ratio from random urine samples to determine 24-hour BJP excretion.

Context: Clinical pathology (CP) laboratories are used for millions of tests each year. These lead to thousands of calls to CP residents. However, although laboratory utilization is a frequent topic of study, clinical utilization--the content of the interactions between clinicians and CP residents--is not. Because it reflects questions about laboratory utilization, clinical utilization could suggest ways to improve both training and care by reducing diagnostic error., Objectives: To build and implement a secure, scalable Web-based system to allow CP residents at any hospital to track the calls they receive, the interaction's context, and the action taken as a result, with evidence where applicable, and to use this system to report on clinical utilization at a major academic hospital., Design: Entries were analyzed from a nearly year-long period to describe the clinical utilization of CP at a large academic teaching hospital., Results: Sixteen residents logged 847 calls during 10 months, roughly evenly distributed among transfusion medicine, chemistry, microbiology, and hematopathology. Calls covered 94 different analytes in chemistry and 71 different organisms or tests in microbiology. Analysis revealed areas where CP can improve clinical care through educating the clinical services, for example, about ordering Rh immune globulin, testosterone testing, and diagnosis of tick-borne diseases. Documenting calls also highlighted patterns among residents., Conclusions: Clinical utilization is a potentially rich knowledge base for improving patient care and resident training. Our resident call-tracking system is a useful way for measuring clinical utilization and mining it for actionable information.

Background: The D-dimer assay has been shown to be an appropriate test to rule out pulmonary embolism (PE) in low-risk patients in the emergency department (ED). Multiple assays now are approved to measure D-dimer levels. Studies have shown a newer assay, Tina-quant, to have similar diagnostic accuracy to the VIDAS assay., Objectives: The objective was to determine effects of transitioning from the VIDAS assay to the Tina-quant D-dimer assay on the need for computed tomography angiogram (CTA) and ED length of stay (LOS) in patients being evaluated for PE in the ED., Methods: A retrospective cohort study was conducted of patients who had D-dimer levels ordered at an urban, academic, Level I trauma center with over 55,000 annual ED visits. The results of D-dimer levels in the ED were recorded over a period of 6 months prior to and 6 months after the transition to the new D-dimer assay. The numbers of positive and negative D-dimers and need for subsequent CTAs were recorded for comparison. LOS was also recorded to determine time saved. Medians were calculated and compared using Wilcoxon rank sum., Results: During the initial period, 875 D-dimers were ordered, with a positive rate of 41.5%. During the period after the introduction of the Tina-quant assay, 859 tests were ordered, with 25.5% having positive results. An absolute decrease of 16% in the number of necessary CTAs (p < 0.003) was seen after the transition to the Tina-quant assay. LOS data showed a mean LOS of 481 minutes in the ED for patients who underwent testing with the Tina-quant assay compared to 526 minutes with the VIDAS assay, saving an average of 45 minutes per patient (p < 0.003). The positive rate on performed imaging studies for D-dimer of > 500 rose from 13 of 308 (4.2%) to 17 of 187 (9.1%)., Conclusions: Switching D-dimer assays reduced both LOS and number of imaging studies in our patient population., (© 2011 by the Society for Academic Emergency Medicine.)

Background: Alterations in serum biomarkers have been used to evaluate for pancreatitis in the emergency department (ED). Studies have shown lipase to be as sensitive and more specific than amylase in diagnosing pancreatitis and that amylase plus lipase does not improve accuracy over lipase alone., Objective: To determine effects of interventions to decrease ordering of amylase in the evaluation of pancreatitis., Methods: We conducted a pre- and post-cohort study. The number of amylase and lipase tests ordered in the ED was recorded prior to intervention to establish a baseline. We introduced an educational intervention to order lipase without amylase. A second intervention involved removing amylase from bedside order entry forms. We introduced a third intervention that included deleting amylase from trauma order forms, and decoupling amylase and lipase in the computer ordering system. We recorded the number of lipase and amylase tests in weekly aggregates for comparison to the baseline. Data analysis using students t-test, standard deviation and p values are reported., Results: Before interventions 93% of patients had both tests ordered. Educational interventions resulted in a decrease to 91% (p=0.06) of co-ordering. Further interventions decreased the percentage of patients evaluated with both tests to 14.3%. This translates into a decrease in patient charges of approximately $350,000 a year., Conclusion: Using simple structured interventions in the ED can reduce amylase ordering. Educational programming alone was not effective in significantly decreasing amylase ordering; however, education plus system-based interventions decreased amylase ordering.

Objective: To determine if pre-eclampsia is associated with reduced thyroid function during and after pregnancy., Design: Nested case-control study during pregnancy and population based follow-up study after pregnancy., Setting: Calcium for Pre-eclampsia Prevention trial of healthy pregnant nulliparous women in the United States during 1992-5, and a Norwegian population based study (Nord-Trondelag Health Study or HUNT-2) during 1995-7 with linkage to the medical birth registry of Norway., Participants: All 141 women (cases) in the Calcium for Pre-eclampsia Prevention trial with serum measurements before 21 weeks' gestation (baseline) and after onset of pre-eclampsia (before delivery), 141 normotensive controls with serum measurements at similar gestational ages, and 7121 women in the Nord-Trondelag Health Study whose first birth had occurred in 1967 or later and in whom serum levels of thyroid stimulating hormone had been subsequently measured., Main Outcome Measures: Thyroid function tests and human chorionic gonadotrophin and soluble fms-like tyrosine kinase 1 concentrations in the Calcium for Pre-eclampsia Prevention cohort and odds ratios for levels of thyroid stimulating hormone above the reference range, according to pre-eclampsia status in singleton pregnancies before the Nord-Trondelag Health Study., Results: In predelivery specimens of the Calcium for Pre-eclampsia Prevention cohort after the onset of pre-eclampsia, thyroid stimulating hormone levels increased 2.42 times above baseline compared with a 1.48 times increase in controls. The ratio of the predelivery to baseline ratio of cases to that of the controls was 1.64 (95% confidence interval 1.29 to 2.08). Free triiodothyronine decreased more in the women with pre-eclampsia than in the controls (case ratio to control ratio 0.96, 95% confidence interval 0.92 to 0.99). The predelivery specimens but not baseline samples from women with pre-eclampsia were significantly more likely than those from controls to have concentrations of thyroid stimulating hormone above the reference range (adjusted odds ratio 2.2, 95% confidence interval 1.1 to 4.4). Both in women who developed pre-eclampsia and in normotensive controls the increase in thyroid stimulating hormone concentration between baseline and predelivery specimens was strongly associated with increasing quarters of predelivery soluble fms-like tyrosine kinase 1 (P for trend 0.002 and <0.001, respectively). In the Nord-Trondelag Health Study, women with a history of pre-eclampsia in their first pregnancy were more likely than other women (adjusted odds ratio 1.7, 95% confidence interval 1.1 to 2.5) to have concentrations of thyroid stimulating hormone above the reference range (>3.5 mIU/l). In particular, they were more likely to have high concentrations of thyroid stimulating hormone without thyroid peroxidase antibodies (adjusted odds ratio 2.6, 95% confidence interval 1.3 to 5.0), suggesting hypothyroid function in the absence of an autoimmune process. This association was especially strong (5.8, 1.3 to 25.5) if pre-eclampsia had occurred in both the first and the second pregnancies., Conclusion: Increased serum concentration of soluble fms-like tyrosine kinase 1 during pre-eclampsia is associated with subclinical hypothyroidism during pregnancy. Pre-eclampsia may also predispose to reduced thyroid function in later years.

The objective was to determine the effect of a proposed increase in the upper reference limits of serum creatine kinase (CK) on neuromuscular disease diagnosis. This was a retrospective study of 94 Caucasian subjects (49 women and 45 men) in whom a neuromuscular physician ordered a CK as part of their evaluation. The patients were divided into two groups: those with diagnoses that either should or could elevate serum CK, and those with diagnoses that should not elevate serum CK. Sensitivities and specificities of the manufacturer's and the newly proposed upper reference limits were determined. For women, raising the upper reference limit of CK from 140 IU/L to 201 IU/L reduced the sensitivity of the test from 50% to 29%, while increasing the specificity from 67% to 80%. For men, raising the upper reference limit of CK from 174 IU/L to 322 IU/L reduced the sensitivity from 80% to 60%, while increasing the specificity from 63% to 80%. The newly proposed upper reference limits resulted in a false-negative CK of clinical significance in 7 of 94 subjects. Increasing the upper reference limit for CK reduced the sensitivity and increased the specificity of serum CK for neuromuscular disease diagnosis. Such a change will reduce unnecessary referrals and invasive diagnostic testing in patients with asymptomatic CK elevations. The clinical impact of the loss in sensitivity is small. If these new upper reference limits are adopted, neuromuscular physicians should be aware that a normal CK level does not exclude a diagnosis of myopathy.

MODULAR ANALYTICS Serum Work Area (in USA Integrated MODULAR ANALYTICS, MODULAR ANALYTICS is a trademark of a member of the Roche Group) represents a further approach to automation in the laboratory medicine. This instrument combines previously introduced modular systems for the clinical chemistry and immunochemistry laboratory and allows customised combinations for various laboratory workloads. Functionality, practicability, and workflow behaviour of MODULAR ANALYTICS Serum Work Area were evaluated in an international multicenter study at six laboratories. Across all experiments, 236000 results from 32400 samples were generated using 93 methods. Simulated routine testing which included provocation incidents and anomalous situations demonstrated good performance and full functionality. Heterogeneous immunoassays, performed on the E-module with the electrochemiluminescence technology, showed reproducibility at the same level of the general chemistry tests, which was well within the clinical demands. Sample carryover cannot occur due to intelligent sample processing. Workflow experiments for the various module combinations, with menus of about 50 assays, yielded mean sample processing times of <38 minutes for combined clinical chemistry and immunochemistry requests; <50 minutes including automatically repeated samples. MODULAR ANALYTICS Serum Work Area offered simplified workflow by combining various laboratory segments. It increased efficiency while maintaining or even improving quality of laboratory processes.

We studied the prevalence and nature of immunoglobulin abnormalities in HIV-1-infected patients in the era of highly active antiretroviral therapy. Protein electrophoreses (PEP) were performed on and quantitative immunoglobulin levels obtained in samples from 320 consecutive HIV-1-infected patients. Samples with possible PEP abnormalities underwent immunofixation. The PEP pattern was normal in 83.8% of samples, 8.1% had subtle oligoclonal banding, and 4.4% had a low-concentration (<5% of total protein) monoclonal band. Hypogammaglobulinemia and polyclonal hypergammaglobulinemia accounted for 1.9% each. In multivariate analysis, younger age (odds ratio [OR], 1.06 with each decreasing year of life; 95% confidence interval [CI], 1.02-1.11; P = .016), female sex (OR, 2.4; 95% CI, 1.13-5.11; P = .02), viral load (OR, 1.50 with each increasing logarithmic viral load of 1.0; 95% CI, 1.14-1.98; P = .004), and CD4 cell count (> or =350 vs <350/microL [0.35 x 10(9)/L]) (OR, 2.71; 95% CI, 1.09-6.75; P = .032) were associated with monoclonal or oligoclonal banding. These results suggest that younger HIV-1-infected patients with a more robust immune system (higher CD4 cell count), which is stimulated by uncontrolled viremia, are most likely to have an augmented B-cell response to HIV infection. One manifestation of this B-cell response is low-concentration monoclonal banding in 4.4% of the patients studied.

We report the first successful study of the use of Raman spectroscopy for quantitative, noninvasive ("transcutaneous") measurement of blood analytes, using glucose as an example. As an initial evaluation of the ability of Raman spectroscopy to measure glucose transcutaneously, we studied 17 healthy human subjects whose blood glucose levels were elevated over a period of 2-3 h using a standard glucose tolerance test protocol. During the test, 461 Raman spectra were collected transcutaneously along with glucose reference values provided by standard capillary blood analysis. A partial least squares calibration was created from the data from each subject and validated using leave-one-out cross validation. The mean absolute errors for each subject were 7.8%+/-1.8% (mean+/-std) with R2 values of 0.83+/-0.10. We provide spectral evidence that the glucose spectrum is an important part of the calibrations by analysis of the calibration regression vectors., (2005 Society of Photo-Optical Instrumentation Engineers.)

MODULAR ANALYTICS (Roche Diagnostics) (MODULAR ANALYTICS, Elecsys and Cobas Integra are trademarks of a member of the Roche Group) represents a new approach to automation for the clinical chemistry laboratory. It consists of a control unit, a core unit with a bidirectional multitrack rack transportation system, and three distinct kinds of analytical modules: an ISE module, a P800 module (44 photometric tests, throughput of up to 800 tests/h), and a D2400 module (16 photometric tests, throughput up to 2400 tests/h). MODULAR ANALYTICS allows customised configurations for various laboratory workloads. The performance and practicability of MODULAR ANALYTICS were evaluated in an international multicentre study at 16 sites. Studies included precision, accuracy, analytical range, carry-over, and workflow assessment. More than 700 000 results were obtained during the course of the study. Median between-day CVs were typically less than 3% for clinical chemistries and less than 6% for homogeneous immunoassays. Median recoveries for nearly all standardised reference materials were within 5% of assigned values. Method comparisons versus current existing routine instrumentation were clinically acceptable in all cases. During the workflow studies, the work from three to four single workstations was transferred to MODULAR ANALYTICS, which offered over 100 possible methods, with reduction in sample splitting, handling errors, and turnaround time. Typical sample processing time on MODULAR ANALYTICS was less than 30 minutes, an improvement from the current laboratory systems. By combining multiple analytic units in flexible ways, MODULAR ANALYTICS met diverse laboratory needs and offered improvement in workflow over current laboratory situations. It increased overall efficiency while maintaining (or improving) quality.

Concentrations of multiple analytes were simultaneously measured in whole blood with clinical accuracy, without sample processing, using near-infrared Raman spectroscopy. Spectra were acquired with an instrument employing nonimaging optics, designed using Monte Carlo simulations of the influence of light-scattering-absorbing blood cells on the excitation and emission of Raman light in turbid medium. Raman spectra were collected from whole blood drawn from 31 individuals. Quantitative predictions of glucose, urea, total protein, albumin, triglycerides, hematocrit, and hemoglobin were made by means of partial least-squares (PLS) analysis with clinically relevant precision (r(2) values >0.93). The similarity of the features of the PLS calibration spectra to those of the respective analyte spectra illustrates that the predictions are based on molecular information carried by the Raman light. This demonstrates the feasibility of using Raman spectroscopy for quantitative measurements of biomolecular contents in highly light-scattering and absorbing media.

Context: Diagnosis of subarachnoid hemorrhage is usually established by computed tomographic scanning; however, in a few patients, lumbar puncture to examine the cerebrospinal fluid for erythrocytes and xanthochromia is necessary. Some authorities recommend delaying lumbar puncture by 12 hours following onset of symptoms to ensure sufficient time has elapsed for xanthochromia to develop. This recommendation is based on measuring xanthochromia by spectrophotometry. Our hypothesis was that very few hospital laboratories in the United States use this method., Objective: To determine the percentage of hospital clinical laboratories that measure for xanthochromia using spectrophotometry., Design, Setting, and Participants: Mail survey to 3500 hospital clinical laboratory directors (in collaboration with the College of American Pathologists). Surveys were mailed in January 2001 and the results tabulated 1 month later. Participation was voluntary., Main Outcome Measures: Percentage of hospital clinical laboratories that use spectrophotometry versus visual inspection., Results: Of the 3500 laboratories surveyed, 2551 (72.9%) responded. Of these, 1944 (76.2%) indicated that they evaluated for xanthochromia. Of the 1952 laboratories that answered the question "How do you report your results?" 1947 (99.7%) reported using visual inspection., Conclusions: When evaluating for xanthochromia in cerebrospinal fluid, nearly all hospital clinical laboratories in the United States use visual inspection. Given this current reality, the recommendation of delaying lumbar puncture by 12 hours needs to be reassessed.