Total plasma homocysteine measurement: Evaluation of the Abbott immunoassay, comparison with the JEOL ion exchange chromatography and investigation of its clinical utility.

Objectives: Homocysteine is an intermediary amino acid formed in methionine metabolism, with elevated total homocysteine (tHCY) being a biomarker of cardiovascular and cerebrovascular diseases. We evaluated the Abbott ARCHITECT tHCY immunoassay, compared it with the current established JEOL ion exchange chromatography (IEC) method and evaluated its clinical utility. Design and methods: Following immunoassay method verification, plasma samples of 91 patients were analysed for tHCY using immunoassay and IEC. Results: For the Abbott immunoassay, accuracy was assessed, with UK NEQAS EQA specimens, by the correlation of our Abbott immunoassay measurements to the Abbott ARCHITECT immunoassay mean (bias = 1.6%), and to the overall immunoassay mean (bias = 2.0%). The total imprecision was 2.7% (11.00 µmol/L), 2.4% (16.80 µmol/L) and 2.8% (24.30 µmol/L) respectively. Bias in linearity assessment was 0.12%-2.58%. The inter-method correlation was strong in Passing-Bablok regression: immunoassay = IEC x0.857 + 2.445 (95% CI: slope = [0.742,0.947], intercept = [1.340,3.582]), with Spearman correlation = 0.803 (p < 0.001). The Bland-Altman plot showed an average difference of -0.284 µmol/L (95% CI: [-1.043,0.474]) with limits of agreement (mean ± 1.96SD) from -7.425 µmol/L to 6.857 µmol/L.No significant difference in tHCY was found using both methods in patients with cerebrovascular diseases and cardiovascular diseases. Most tHCY measurements were within the reference ranges of both methods. All homocystinuria patients had tHCY values above the reference ranges of both methods. Conclusions: The immunoassay demonstrated robust performance in its verification and showed good comparability with the IEC but with some biases so caution is needed if both are used interchangeably. The immunoassay offers an automated alternative to IEC in the assessment of hyperhomocysteinaemia.

Performance characteristics of five SARS-CoV-2 serological assays: Clinical utility in health-care workers.

STUDY OBJECTIVE: SARS-CoV-2, which causes coronavirus disease (COVID-19), continues to cause significant morbidity and mortality. The diagnosis of acute infection relies on reverse transcription-polymerase chain reaction (RT-PCR)-based viral detection. The objective of this study was to evaluate the optimal serological testing strategy for anti-SARS-CoV-2 antibodies which provides an important indicator of prior infection and potential short-term immunity. METHODS: The sensitivity and specificity of four different ELISA assays (Euroimmun IgG, Euroimmun NCP-IgG, Fortress and DIAsource) and one CLIA assay (Roche ELECSYS) were evaluated in 423 samples; 137 patients with confirmed RT-PCR COVID-19 infection (true positives), and 100 pre-pandemic samples collected prior to October 2019 (true negatives). A further 186 samples were collected from health-care staff and analysed by all five assays. RESULTS: The Fortress ELISA assay demonstrated the highest sensitivity and specificity followed by the Roche ECLIA assay. The highest overall sensitivity came from the assays that measured total antibody (IgM-IgG combined) and the three assays that performed the best (Fortress, Roche, Euroimmun IgG) all have different antigens as their target proteins which suggests that antigen target does not affect assay performance. In mildly symptomatic participants with either a negative RT-PCR or no RT-PCR performed, 16.76% had detectable antibodies suggesting previous infection. CONCLUSIONS: We recommend a combined testing strategy utilizing assays with different antigenic targets using the fully automated Roche ECLIA assay and confirming discordant samples with the Fortress Total Antibody ELISA assay. This study provides an important indicator of prior infection in symptomatic and asymptomatic individuals.

Correction to: Can routine perioperative haemodynamic parameters predict postoperative morbidity after major surgery?

[This corrects the article DOI: 10.1186/s13741-020-0139-6.].

Can routine perioperative haemodynamic parameters predict postoperative morbidity after major surgery?

BACKGROUND: Postoperative morbidity occurs in 10-15% of patients undergoing major noncardiac surgery. Predicting patients at higher risk of morbidity may help to optimize perioperative prevention. Preoperative haemodynamic parameters, systolic arterial pressure (SAP) < 100 mmHg, pulse pressure (PP) > 62 mmHg or < 53 mmHg, and heart rate (HR) > 87 min-1 are associated with increased postoperative morbidity. We evaluated the correlation between these and other routine haemodynamic parameters, measured intraoperatively, with postoperative morbidity. Postoperative morbidity was measured using the Comprehensive Complication Index (CCI) and length of stay (LOS). Additionally we correlated CCI with the cardiac risk biomarker, preoperative NT-ProBNP. METHODS: This is a retrospective analysis of patients in MET-REPAIR, a European observational study correlating self-reported physical activity with postoperative morbidity. Patients' electronic anaesthetic records (EARs) including perioperative haemodynamic data were correlated with 30-day postoperative morbidity, CCI and LOS parameters. Statistical analysis to assess for correlation was by Kendall's Correlation Coefficient for tied ranks (Tau-B) or Spearman's Correlation Coefficient. Blood for N-terminal prohormone of brain natriuretic peptide (NT-proBNP) measurement was collected < 31 days before surgery. RESULTS: Data from n = 50 patients were analysed. When stratified according to age > 70 years and ASA > 3, the duration of MAP < 100 mmHg, < 75 mmHg or < 55 mmHg were associated with a higher CCI (tau = 0.57, p = 0.001) and duration < 75 mmHg was associated with prolonged LOS (tau = 0.39, p = 0.02). The intraoperative duration of PP > 62 mmHg was associated with LOS (tau = 0.317, p = 0.007). There was no correlation between preoperative NT-proBNP and either CCI or LOS. CONCLUSIONS: In older and higher risk patients, duration of intraoperative hypotension by a variety of definitions, or PP > 62 mmHg, are associated with increased postoperative CCI and LOS. These findings warrant confirmation in larger databases with evaluation of whether real-time intraoperative intervention could reduce postoperative morbidity.

The aldosterone to renin ratio in the diagnosis of primary aldosteronism: Promises and challenges.

The complexity of evaluating patients for secondary treatable causes of hypertension is underappreciated. Primary aldosteronism (PA) is the most prevalent cause of secondary hypertension (3%-32% of hypertensive patients). The recent endocrine society clinical practice guideline (ESCPG), "The Management of Primary Aldosteronism: Case Detection, Diagnosis, and Treatment", differs from the previous version in the explicit recognition of PA as a major public health issue. Despite this, PA is underdiagnosed. The guidelines call on physicians to substantially ramp up the screening of hypertensive patients at risk of PA. Further, it recommends the plasma aldosterone to renin ratio (ARR), as the test of choice for screening for PA. However, the ARR is a highly variable test with reported diagnostic sensitivities and specificities ranging from 66% to 100% and 61% to 100%, respectively. Variability of the ARR can be attributed to the high degree of within-subject variation, differences in sampling protocols, laboratory assays, reporting units, the effect of medications and the population characteristics used to establish the decision thresholds. These factors render the possibility of false positive and false negative results-which have the potential to adversely impact patients. The limitations and caveats to the use of the ARR necessitate an effective clinic-laboratory interface, with specialist physician and clinical scientist collaboration for ARR result interpretation. Improvement in the diagnostic sensitivity and specificity of the ARR is predicated on harmonisation of pretesting patient preparation criteria, knowledge of the analytical methods used to derive the ratio and the method-specific threshold for PA.

Fertility in classical galactosaemia, a study of N-glycan, hormonal and inflammatory gene interactions.

BACKGROUND: Classical Galactosaemia (CG) (OMIM #230400) is a rare inborn error of galactose metabolism caused by deficiency of the enzyme galactose-1-phosphate uridylyltransferase (GALT). Long-term complications persist in treated patients despite dietary galactose restriction with significant variations in outcomes suggesting epigenetic glycosylation influences. Primary Ovarian Insufficiency (POI) is a very significant complication affecting females with follicular depletion noted in early life. We studied specific glycan synthesis, leptin system and inflammatory gene expression in white blood cells as potential biomarkers of infertility in 54 adults with CG adults (27 females and 27 males) (age range 17-51 yr) on a galactose-restricted diet in a multi-site Irish and Dutch study. Gene expression profiles were tested for correlation with a serum Ultra-high Performance Liquid Chromatography (UPLC)-Immunoglobulin (IgG)-N-glycan galactose incorporation assay and endocrine measurements. RESULTS: Twenty five CG females (93%) had clinical and biochemical evidence of POI. As expected, the CG female patients, influenced by hormone replacement therapy, and the healthy controls of both genders showed a positive correlation between log leptin and BMI but this correlation was not apparent in CG males. The strongest correlations between serum leptin levels, hormones, G-ratio (galactose incorporation assay) and gene expression data were observed between leptin, its gene and G-Ratios data (rs = - 0.68) and (rs = - 0.94) respectively with lower circulating leptin in CG patients with reduced IgG galactosylation. In CG patients (males and females analysed as one group), the key glycan synthesis modifier genes MGAT3 and FUT8, which influence glycan chain bisecting and fucosylation and subsequent cell signalling and adhesion, were found to be significantly upregulated (p < 0.01 and p < 0.05) and also the glycan synthesis gene ALG9 (p < 0.01). Both leptin signalling genes LEP and LEPR were found to be upregulated (p < 0.01) as was the inflammatory genes ANXA1 and ICAM1 and the apoptosis gene SEPT4 (p < 0.01). CONCLUSIONS: These results validate our previous findings and provide novel experimental evidence for dysregulation of genes LEP, LEPR, ANXA1, ICAM1 and SEPT4 for CG patients and combined with our findings of abnormalities of IgG glycosylation, hormonal and leptin analyses elaborate on the systemic glycosylation and cell signalling abnormalities evident in CG which likely influence the pathophysiology of POI.

Validation of an automated ultraperformance liquid chromatography IgG N-glycan analytical method applicable to classical galactosaemia.

Background Classical galactosaemia (OMIM #230400) is a rare disorder of carbohydrate metabolism caused by deficiency of the galactose-1-phosphate uridyltransferase enzyme. The pathophysiology of the long-term complications, mainly cognitive, neurological and female fertility problems, remains poorly understood. Current clinical methods of biochemical monitoring lack precision and individualization with an identified need for improved biomarkers for this condition. Methods We report the development and detailed validation of an automated ultraperformance liquid chromatography N-glycan analytical method of high peak resolution applied to galactose incorporation into human serum IgG. Samples are prepared on 96-well plates and the workflow features rapid glycoprotein denaturation, enzymatic glycan release, glycan purification on solid-supported hydrazide, fluorescent labelling and post-labelling clean-up with solid-phase extraction. Results This method is shown to be accurate and precise with repeatability (cumulative coefficients of variation) of 2.0 and 8.5%, respectively, for G0/G1 and G0/G2 ratios. Both serum and processed N-glycan samples were found to be stable at room temperature and in freeze-thaw experiments. Conclusions This high-throughput method of IgG galactose incorporation is robust, affordable and simple. This method is validated with the potential to apply as a biomarker for treatment outcomes for galactosaemia.

Generating method-specific Reference Ranges - A harmonious outcome?

OBJECTIVES: When laboratory Reference Ranges (RR) do not reflect analytical methodology, result interpretation can cause misclassification of patients and inappropriate management. This can be mitigated by determining and implementing method-specific RRs, which was the main objective of this study. DESIGN AND METHODS: Serum was obtained from healthy volunteers (Male + Female, n > 120) attending hospital health-check sessions during June and July 2011. Pseudo-anonymised aliquots were stored (at - 70 °C) prior t° analysis on Abbott ARCHITECT c16000 chemistry and i2000SR immunoassay analysers. Data were stratified by gender where appropriate. Outliers were excluded statistically (Tukey method) to generate non-parametric RRs (2.5th + 97.5th percentiles). RRs were compared to those quoted by Abbott and UK Pathology Harmony (PH) where possible. For 7 selected tests, RRs were verified using a data mining approach. RESULTS: For chemistry tests (n = 23), Upper or Lower Reference Limits (LRL or URL) were > 20% different from Abbott ranges in 25% of tests (11% from PH ranges) but in 38% for immunoassay tests (n = 13). RRs (mmol/L) for sodium (138-144), potassium (3.8-4.9) and chloride (102-110) were considerably narrower than PH ranges (133-146, 3.5-5.0 and 95-108, respectively). The gender difference for ferritin (M: 29-441, F: 8-193 ng/mL) was more pronounced than reported by Abbott (M: 22-275, F: 5-204 ng/mL). Verification studies showed good agreement for chemistry tests (mean [SD] difference = 0.4% [1.2%]) but less so for immunoassay tests (27% [29%]), particularly for TSH (LRL). CONCLUSION: Where resource permits, we advocate using method-specific RRs in preference to other sources, particularly where method bias and lack of standardisation limits RR transferability and harmonisation.

Evaluation of cystatin C in malignancy and comparability of estimates of GFR in oncology patients.

OBJECTIVES: Creatinine is the biomarker of choice for use in estimates of kidney function in oncology patients. However as non-renal factors such as muscle mass can influence creatinine concentrations, we evaluated cystatin C as an alternative biomarker and its incorporation in GFR estimating formulae in an oncology setting. Measured GFR is infrequently undertaken in adult clinical practice with the consequent reliance on calculated GFR for patient assessment. DESIGN AND METHODS: Cystatin C and creatinine concentrations were evaluated from 134 oncology patients prior to commencing chemotherapeutic cycles. Estimates of creatinine clearance (Cockroft-Gault) and GFR (using Hoek, Jonsson, MDRD and CKD-EPI) were evaluated. Cystatin C-based GFR estimates (using CKD-EPI CysC and CKD-EPI SCr/CysC) were compared with the creatinine-based GFR estimates (CG, MDRD and CKD-EPI SCr) within the GFR ranges of 60-89, 45-59 and ≤44 mL/min/1.73 m2. RESULTS: Cystatin C concentrations were significantly higher in oncology patients both prior to commencing chemotherapy (F: P<0.01 and M: P<0.0001) and during cycles of treatment (F: P<0.0001 and M: P<0.01) when compared with a reference population. Cystatin C concentrations also increased significantly during chemotherapy (P<0.0001) in a subset of female patients evaluated. Poor agreement (average 42%) was demonstrated between CKD-EPI CysC and creatinine-based GFR estimates within the investigated GFR ranges, with improved agreement (average 55%) when using the combined CKD-EPI SCr/CysC formula. CONCLUSIONS: This study demonstrated a malignancy and treatment-mediated effect on cystatin C measures, which may confound its clinical utility in estimating GFR in oncology patients.

High-sensitive cardiac troponin-I facilitates timely detection of subclinical anthracycline-mediated cardiac injury.

Background Anthracycline drugs are effective anticancer agents, but their optimal use is limited in many patients by the associated cardiotoxicity, even at designated safe doses. As conventionally sensitive cardiac troponin-I assays fail to reliably quantify concentrations of cardiac troponin-I below 30 ng/L, we investigated the potential role of high-sensitive cardiac troponin-I in the detection of subclinical cardiomyocyte injury in patients treated with anthracycline agents. Methods Serial high-sensitive cardiac troponin-I concentrations were assessed in 84 patients, receiving anthracycline-containing ( n = 38) and non-anthracycline-containing ( n = 46) regimens. Results were assessed for change from pretreatment levels and evaluated according to unisex and gender-specific 99th percentiles (25 ng/L and M: 34 ng/L, F: 16 ng/L, respectively). Results A significant increase in high-sensitive cardiac troponin-I was observed in the anthracycline cohort following five cycles of treatment, with the greatest change correlating to an absolute δ increase of 30.7 ng/L in the early-dose group (early-dose group: P < 0.0001, late-dose group: P < 0.01 and continuous-dose group: P < 0.0001). Doxorubicin dose did not correlate directly with high-sensitive cardiac troponin-I concentrations (Spearman r < -0.22). No significant changes in high-sensitive cardiac troponin-I were reported among the non-anthracycline cohort with all measurements below the 99th percentiles. Conclusions Treatment with anthracycline-based chemotherapeutic regimen demonstrated significant elevations of high-sensitive cardiac troponin-I, indicative of subclinical cardiomyocyte damage. This study demonstrates a role for high-sensitive cardiac troponin-I in evaluating those patients where cardiotoxicity is a concern and a potential future role as a biomarker in optimizing cardioprotective treatments in patients receiving anthracycline therapy.

In control? IQC consensus and statutory regulation.

Purpose - Internal quality control (IQC) represents an essential risk management tool within the total testing pathway (TTP) that contributes to the overall objective of assuring the quality of results produced in medical laboratories. Controlling analytical phase quality alone requires significant expertise and input by scientifically trained staff. This effort has escalated exponentially following the publication of the International Organisation for Standardisation (ISO)15189:2012 requirements for quality and competence in medical laboratories. The reported inconsistency and diversity to IQC approaches in diagnostic laboratories is definitive evidence that international guidance in IQC programme design and implementation is long overdue. The paper aims to discuss these issues. Design/methodology/approach - Herein, the authors define, describe and critically examine the essential elements four stages of an IQC programme and suggest a template to inform both design and ease of implementation. For practical application, the authors have stratified the proposed methodology into four stages: staff education and training; IQC material; IQC targets; and IQC procedure, and provide recommendations that meet ISO15189:2012 requirements. Findings - These recommendations are informed by the published literature together with the collective experience working in clinical biochemistry and diagnostic endocrinology laboratories. The authors note that the laboratory staff's effort on IQC is a continuous process, driven by changes within each IQC stage, in response to risk analysis, maximising economic value or through professional leadership and central to IQC programme implementation and delivery. Practical implications - The authors offer a template that laboratories can use to inform the design and implementation of their IQC programme. Originality/value - The proposed IQC programme is user friendly, flexible and pragmatic with the potential to harmonise practice. The authors have provided a template to potentially harmonise IQC practice nationally. Given the central and critical role that IQC practice plays in ensuring the quality of patient results' importance, the authors contend that the time has come for international consensus and statutory regulation regarding the minimally acceptable criteria for its implementation, monitoring and review.

Laboratory services: regaining and maintaining control.

Purpose - After implementing an internal quality control (IQC) programme, the purpose of this paper is to maintain the requisite analytical performance for clinical laboratory staff, thereby safeguarding patient test results for their intended medical purpose. Design/methodology/approach - The authors address how quality can be maintained and if lost, how it can be regained. The methodology is based on the experience working in clinical laboratory diagnostics and is in accord with both international accreditation requirements and laboratory best practice guidelines. Findings - Monitoring test performance usually involves both prospective and retrospective IQC data analysis. The authors present a number of different approaches together with software tools currently available and emerging, that permit performance monitoring at the level of the individual analyser, across analysers and laboratories (networks). The authors make recommendations on the appropriate response to IQC rule warnings, failures and metrics that indicate analytical control loss, that either precludes further analysis, or signifies deteriorating performance and eventual unsuitability. The authors provide guidance on systematic troubleshooting, to identify undesirable performance and consider risk assessment preventive measures and continuous quality improvement initiatives; e.g., material acceptance procedures, as tools to help regain and maintain analytical control and minimise potential for patient harm. Practical implications - The authors provide a template for use by laboratory scientific personnel that ensures the optimal monitoring of analytical test performance and response when it changes undesirably. Originality/value - The proposed template has been designed to meet the International Organisation for Standardisation for medical laboratories ISO15189:2012 requirements and therefore includes the use of External Quality Assessment and patient results data, as an adjunct to IQC data.

Clinical utility of C-terminal telopeptide of type 1 collagen in multiple myeloma.

Myeloma bone disease (MBD) is a major cause of morbidity in multiple myeloma (MM). We investigated bone turnover markers (BTM) as relapse predictors and biomarkers for monitoring MBD. We measured C-terminal telopeptide of type I collagen (CTX-1), and Procollagen type 1 N Propeptide (P1NP) in 86 MM patients and 26 controls. CTX-1 was higher in newly diagnosed patients compared to control, remission and relapse (P < 0·05), and decreased following treatment. In the setting of relapse, a CTX-1 rise greater than the calculated least significant change (LSC) was observed in 26% of patients 3-6 months prior to relapse (P = 0·007), and in 60·8% up to 3 months before relapse (P = 0·015). Statistically significant changes in CTX-1 levels were also observed in patients who were with and without bisphosphonate therapy at the time of relapse. In patients with normal renal function, mean CTX-1 level was highest in the newly diagnosed group (0·771 ± 0·400 µg/l), and lowest in the remission group (0·099 ± 0·070 µg/l) (P < 0·0001). P1NP levels were not statistically different across the patient groups. We conclude that CTX-1, measured on an automated hospital laboratory platform, has a role in routine treatment monitoring and predicting relapse of MBD, even in patients on bisphosphonates.

Classical galactosaemia: novel insights in IgG N-glycosylation and N-glycan biosynthesis.

Classical galactosaemia (OMIM #230400), a rare disorder of carbohydrate metabolism, is caused by a deficient activity of galactose-1-phosphate uridyltransferase (EC 2.7.7.12). The pathophysiology of the long-term complications, mainly cognitive, neurological and female fertility problems remains poorly understood. The lack of validated biomarkers to determine prognosis, monitor disease progression and responses to new therapies, pose a huge challenge. We report the detailed analysis of an automated robotic hydrophilic interaction ultra-performance liquid chromatography N-glycan analytical method of high glycan peak resolution applied to serum IgG. This has revealed specific N-glycan processing defects observed in 40 adult galactosaemia patients (adults and adolescents), in comparison with 81 matched healthy controls. We have identified a significant increase in core fucosylated neutral glycans (P<0.0001) and a significant decrease in core fucosylated (P<0.001), non-fucosylated (P<0.0001) bisected glycans and, of specific note, decreased N-linked mannose-5 glycans (P<0.0001), in galactosaemia patients. We also report the abnormal expression of a number of related relevant N-glycan biosynthesis genes in peripheral blood mononuclear cells from 32 adult galactosaemia patients. We have noted significant dysregulation of two key N-glycan biosynthesis genes: ALG9 upregulated (P<0.001) and MGAT1 downregulated (P<0.01) in galactosaemia patients, which may contribute to its ongoing pathophysiology. Our data suggest that the use of IgG N-glycosylation analysis with matched N-glycan biosynthesis gene profiles may provide useful biomarkers for monitoring response to therapy and interventions. They also indicate potential gene modifying steps in this N-glycan biosynthesis pathway, of relevance to galactosaemia and related N-glycan biosynthesis disorders.

Establishment of reference intervals for aldosterone and renin in a Caucasian population using the newly developed Immunodiagnostic Systems specialty immunoassay automated system.

BACKGROUND: Measurement of aldosterone and/or renin is essential to aid the differential diagnosis of secondary hypertension, guide strategy for therapeutic management of hypertension and assess adequacy of mineralocorticoid replacement. AIM: The objective was to establish normative data for aldosterone and renin using the Immunodiagnostic Systems specialty immunoassay system platform in a Caucasian population. METHODS: Following informed consent, 365 subjects were recruited to this study. Subjects were ambulatory and attended clinic for blood pressure measurement and phlebotomy between the hours of 7:00 and 11:00. Blood pressure was measured according to the 2013 European Society of Hypertension/Cardiology guidelines. The inclusion criteria: age ≥18 years, BMI <30 kg/m(2), non-pregnant, blood pressure <140/90, normal electrolytes and kidney function and not taking prescribed/over the counter medications. Ninety-four subjects were excluded based on these criteria. A total of 271 volunteers (females n = 145), aged 18-65 years formed the reference cohort. Blood for aldosterone/renin was collected into ethylenediaminetetraacetic acid specimen tubes. Samples were kept at room temperature and transported within 30 min of blood draw to the laboratory for immediate processing (centrifugation, separation and freezing of plasma). Plasma was stored at -20℃ prior to analysis on the Immunodiagnostic Systems specialty immunoassay system instrument. RESULTS: The established reference intervals in an Irish Caucasian population for renin: females: 6.1-62.7 mIU/L, males: 9.0-103 mIU/L, for aldosterone: females: <138-1179 pmol/L, males: <138-670 pmol/L, respectively. CONCLUSION: This study demonstrates that reference intervals for aldosterone and renin should be gender specific. These automated immunoassays offer rapid stratification of patients with refractory hypertension and will better facilitate the optimization of therapeutic management.

Transitioning high sensitivity cardiac troponin I (hs-cTnI) into routine diagnostic use: More than just a sensitivity issue.

OBJECTIVES: High sensitivity cardiac troponin T and I (hs-cTnT and hs-cTnI) assays show analytical, diagnostic and prognostic improvement over contemporary sensitive cTn assays. However, given the importance of troponin in the diagnosis of myocardial infarction, implementing this test requires rigorous analytical and clinical verification across the total testing pathway. This was the aim of this study. DESIGN AND METHODS: Analytical verification included assessment of critical outlier frequency, for hs-cTnI and cTnI assays. Concordance for paired cTnI and hs-cTnI measurements (n=1096) was verified using 99th percentiles for both genders (cTnI: 30 ng/L, hs-cTnI: 25 ng/L) and for men and women separately (hs-cTnI: M: 34;F: 16 ng/L). Discordant data was correlated with clinical and laboratory information. Diagnosis of Acute Coronary Syndrome (ACS) or Non-ACS was adjudicated by two cardiologists independently. RESULTS: The hs-cTnI assay showed a lower (10-fold) critical outlier rate (0.091%) and more detectable results above the limit of detection (LOD) (23.4%) and 99th percentile (2.4%), compared to cTnI. Analytical concordance between the two assays was high (94.5%) but decreased (91.7%) when gender-specific hs-cTnI cut-offs were used. The hs-cTnI assay gave fewer false negatives (up to 1.0%) but disproportionately more false positives (up to 6.7%) overall, which improved (3.9%) for serial measurements. CONCLUSIONS: Laboratories should analytically and clinically verify hs-cTn assays before use, with attention to performance and the clinical and diagnostic algorithms that support appropriate testing and result interpretation. Work in the pre- and post-analytical phases is necessary to augment the analytical improvement in the new era of troponin testing.

IgG N-Glycosylation Galactose Incorporation Ratios for the Monitoring of Classical Galactosaemia.

Classical galactosaemia (OMIM #230400) is a rare disorder of carbohydrate metabolism caused by deficiency of the galactose-1-phosphate uridyltransferase enzyme (EC 2.7.7.12). The cause of the long-term complications, including neurological, cognitive and fertility problems in females, remains poorly understood. The relatively small number of patients with galactosaemia and the lack of validated biomarkers pose a substantial challenge for determining prognosis and monitoring disease progression and responses to new therapies. We report an improved method of automated robotic hydrophilic interaction ultra-performance liquid chromatography N-glycan analysis for the measurement of IgG N-glycan galactose incorporation ratios applied to the monitoring of adult patients with classical galactosaemia. We analysed 40 affected adult patients and 81 matched healthy controls. Significant differences were noted between the G0/G1 and G0/G2 incorporation ratios between galactosaemia patients and controls (p < 0.001 and <0.01, respectively). Our data indicate that the use of IgG N-glycosylation galactose incorporation analysis may be now applicable for monitoring patient dietary compliance, determining prognosis and the evaluation of potential new therapies.

Detection of high-sensitivity troponin in outpatients with stable pulmonary hypertension identifies a subgroup at higher risk of adverse outcomes.

BACKGROUND: The detection of elevations in cardiorenal biomarkers, such as troponins, B-type natriuretic peptides (BNPs), and neutrophil gelatinase-associated lipocalins, are associated with poor outcomes in patients hospitalized with acute heart failure. Less is known about the association of these markers with adverse events in chronic right ventricular dysfunction due to pulmonary hypertension, or whether their measurement may improve risk assessment in the outpatient setting. METHODS AND RESULTS: We performed a cohort study of 108 patients attending the National Pulmonary Hypertension Unit in Dublin, Ireland, from 2007 to 2009. Cox proportional hazards analysis and receiver operating characteristic curves were used to determine predictors of mortality and hospitalization. Death or hospitalization occurred in 50 patients (46.3%) during the median study period of 4.1 years. Independent predictors of mortality were: 1) decreasing 6-minute walk test (6MWT; hazard ratio [HR] 12.8; P < .001); 2) BNP (HR 6.68; P < .001); and 3) highly sensitive troponin (hsTnT; HR 5.48; P < .001). Adjusted hazard analyses remained significant when hsTnT was added to a model with BNP and 6MWT (HR 9.26, 95% CI 3.61-23.79), as did the predictive ability of the model for death and rehospitalization (area under the receiver operating characteristic curve 0.81, 95% CI 0.73-0.90). CONCLUSIONS: Detection of troponin using a highly sensitive assay identifies a pulmonary hypertension subgroup with a poorer prognosis. hsTnT may also be used in a risk prediction model to identify patients at higher risk who may require escalation of targeted pulmonary vasodilator therapies and closer clinical surveillance.

Peri-operative troponin monitoring using a prototype high-sensitivity cardiac troponin I (hs-cTnI) assay: comparisons with hs-cTnT and contemporary cTnI assays.

BACKGROUND: Non-cardiac surgery is associated with major vascular complications and higher incidences of elevated plasma troponin (cTn) concentration. Goal-directed therapy (GDT) is a stroke volume (SV)-guided approach to intravenous (IV) fluid therapy that improves tissue perfusion, oxygenation and reduces post-operative complications. In patients undergoing major gastro-intestinal surgery, we compared high sensitive and contemporary troponin assays and correlated results with patient outcome. METHODS: Patients (n = 135) were randomized to receive IV fluid, guided by either the central venous pressure (CVP group, n = 45) or SV (± dopexamine inotrope, n = 45 per group). Serum was obtained pre- and post-operatively (0, 8 and 24 h) for troponin analysis by a prototype hs-cTnI assay (Abbott Laboratories), hs-cTnT (Roche Diagnostics) and contemporary cTnI (Beckman Coulter) assays. RESULTS: All troponin measurements were increased (P ≤ 0.05) post-operatively but there was no difference (P > 0.05) amongst treatments. Post-operative increases were reported more frequently (P ≤ 0.05) and earlier with hs-cTnI. Temporal increases (P ≤ 0.05) were reported in patients with and without complications for hs-cTnI/T assays but only in the complications group for cTnI measurements. Elevations ≥99th centile occurred most often (P ≤ 0.05) for hs-cTnT measurements but with similar frequency for both outcome groups (all assays). Only the hs-cTnI assay showed an increased relative risk of mortality (P ≤ 0.05) for elevations ≥99th centile CONCLUSIONS: Our study may suggest a possible preference for the hs-cTnI assay in the peri-operative setting; however, our findings should be verified for larger cohort studies where emerging reference range data is incorporated for improving risk prediction with hs-cTn assays.