Search

Background The comparability of thyroid-stimulating hormone (TSH) results cannot be easily obtained using SI-traceable reference measurement procedures (RPMs) or reference materials, whilst harmonization is more feasible. The aim of this study was to identify and validate a new approach for the harmonization of TSH results. Methods Percentile normalization was applied to 125,419 TSH results, obtained from seven laboratories using three immunoassays (Access 3rd IS Thyrotropin, Beckman Coulter Diagnostics; Architect System, Abbott Diagnostics and Elecsys, Roche Diagnostics). Recalibration equations (RCAL) were derived by robust regressions using bootstrapped distribution. Two datasets, the first of 119 EQAs, the second of 610, 638 and 639 results from Access, Architect and Elecsys TSH results, respectively, were used to validate RCAL. A dataset of 142,821 TSH values was used to derive reference intervals (RIs) after applying RCAL. Results Access, Abbott and Elecsys TSH distributions were significantly different (p < 0.001). RCAL intercepts and slopes were -0.003 and 0.984 for Access, 0.032 and 1.041 for Architect, -0.031 and 1.003 for Elecsys, respectively. Validation using EQAs showed that before and after RCAL, the coefficients of variation (CVs) or among-assay results decreased from 10.72% to 8.16%. The second validation dataset was used to test RCALs. The median of between-assay differences ranged from -0.0053 to 0.1955 mIU/L of TSH. Elecsys recalibrated to Access (and vice-versa) showed non-significant difference. TSH RI after RCAL resulted in 0.37-5.11 mIU/L overall, 0.49-4.96 mIU/L for females and 0.40-4.92 mIU/L for males. A significant difference across age classes was identified. Conclusions Percentile normalization and robust regression are valuable tools for deriving RCALs and harmonizing TSH values.

Background Point-of-care testing has been developed to provide rapid test results. Most published studies focus on analytical performance, neglecting its impact on patient outcomes. Objective To review the analytical performance and accuracy of point-of-care testing specifically planned for immunoassay and to evaluate the impact of faster results on patient management. Methods A search of electronic databases for studies reporting immunoassay results obtained in both point-of-care testing and central laboratory scenarios was performed. Data were extracted concerning the study details, and the methodological quality was assessed. The analytical characteristics and diagnostic accuracy of six points-of-care testing: troponin, procalcitonin, parathyroid hormone, brain natriuretic peptide, C-reactive protein and neutrophil gelatinase-associated lipocalin were evaluated. Results A total of 116 scientific papers were analysed. Studies measuring procalcitonin, parathyroid hormone and neutrophil gelatinase-associated lipocalin reported a limited impact on diagnostic decisions. Seven studies measuring C-reactive protein claimed a significant reduction of antibiotic prescription. Several authors evaluated brain natriuretic peptide or troponin reporting faster decision-making without any improvement in clinical outcome. Forty-four per cent of studies reported analytical data, showing satisfactory correlations between results obtained through point-of-care testing and central laboratory setting. Half of studies defined the diagnostic accuracy of point-of-care testing as acceptable for troponin (median sensitivity and specificity: 74% and 94%, respectively), brain natriuretic peptide (median sensitivity and specificity: 82% and 88%, respectively) and C-reactive protein (median sensitivity and specificity 85%). Conclusions Point-of-care testing immunoassay results seem to be reliable and accurate for troponin, brain natriuretic peptide and C-reactive protein. The satisfactory analytical performance, together with an excellent practicability, suggests that it could be a consistent tool in clinical practice, but data are lacking regarding the patient outcomes.

Background: The neutrophil gelatinase associated lipocalin (NGAL) has been identified as the most promising biomarker of acute kidney injury (AKI). This study was aimed to evaluate a NGAL immunoassay on Beckman Coulter AU 5822., Methods: NGAL Test™ (BioPorto Diagnostics A/S) is a particle-enhanced turbidimetric immunoassay. The within-and between-run imprecision were assessed on three urine samples. The linearity was assessed by serially diluting two urine samples with low and high NGAL concentration. The comparison study was performed with Abbott ARCHITECT NGAL, on 70 urine samples., Results: The within-run imprecision was comprised between 1.0% and 2.3%, whereas the between-run imprecision was between 1.2% and 2.0%. The linearity was excellent in the range between 18 ng/mL and 790 ng/mL (r=1.000; p<0.001). A highly significant agreement was observed between NGAL Test™ on Beckman Coulter AU5822 and Abbott ARCHITECT NGAL (r=0.925; p<0.001), although the method exhibited a bias of +65%. Excellent sensitivity and specificity against the ARCHITECT values were found at 200 ng/mL., Conclusions: This analytical evaluation attests that the NGAL Test™ has several technical and analytical advantages, including no manual pretreatment, low volume of sample (i.e., 3 μL), fast turnaround time (approx. 10 min), low imprecision, wide dynamic range, optimal linearity.

Background: Nucleic Acid Amplification Test (NAAT) can detect the SARS-CoV-2 at low viral load, but the risk of isolating unnecessarily people who are no longer infectious may preclude its use as screening test. Immunoassay can be an alternative screening tool to detect viral antigens, thanks to their high throughput, feasibility and practicability. In this study, we compare the results obtained by a chemiluminescent immunoassay against the molecular test. Methods: 105 positive NAAT nasopharyngeal swabs (NPS) with threshold cycle (Ct) between 39 and 13, and 15 negative samples were analyzed with two different methods based on chemiluminescent technology (CLIA) targeted to nucleocapsid SARS-Cov-2 antigen: Maglumi (SNIBE diagnostic Shenzen, China), and Liaison XL (DiaSorin s.p.a., Saluggia, Italy). Results: all 15 negative NPS (Ct >40) were confirmed as negative with both CLIA assays; 31 positive NPS out of 105 positive (Ct ≤40) were confirmed positive on Maglumi and Liaison (29.5%). The agreement between the two immunoassays was 100%. Conclusions: as expected, CLIA tests demonstrated to be less sensitive to the viral presence than NAAT. In particular, Maglumi and Liaison can detect a positivity when the virus is detected at a Ct <25. The range between 24 and 25 Ct was a grey area, where NAAT and CLIA were not in perfect agreement. It seems that antigen tests reach satisfactory sensitivities when infected people are more likely to be contagious; this characteristic makes them a useful tool for screening the population, especially during the pandemic [ABSTRACT FROM AUTHOR]

Background: The neutrophil gelatinase associated lipocalin (NGAL) has been identified as the most promising biomarker of acute kidney injury (AKI). This study was aimed to evaluate a NGAL immunoassay on Beckman Coulter AU 5822. Methods: NGAL Test™ (BioPorto Diagnostics A/S) is a particle-enhanced turbidimetric immunoassay. The within-and between-run imprecision were assessed on three urine samples. The linearity was assessed by serially diluting two urine samples with low and high NGAL concentration. The comparison study was performed with Abbott ARCHITECT NGAL, on 70 urine samples. Results: The within-run imprecision was comprised between 1.0% and 2.3%, whereas the between-run imprecision was between 1.2% and 2.0%. The linearity was excellent in the range between 18 ng/mL and 790 ng/mL (r=1.000; p<0.001). A highly significant agreement was observed between NGAL Test™ on Beckman Coulter AU5822 and Abbott ARCHITECT NGAL (r=0.925; p<0.001), although the method exhibited a bias of +65%. Excellent sensitivity and specificity against the ARCHITECT values were found at 200 ng/mL. Conclusions: This analytical evaluation attests that the NGAL Test™ has several technical and analytical advantages, including no manual pretreatment, low volume of sample (i.e., 3 μL), fast turnaround time (approx. 10 min), low imprecision, wide dynamic range, optimal linearity. [ABSTRACT FROM AUTHOR]

Abstract: Human chorionic gonadotropin (hCG) is a 237 aminoacid glycoprotein hormone composed of two dissimilar α and β subunits noncovalently linked by charge interactions, which are both required for the biological activity of the hormone. Due to structural heterogeneity, hCG exists in biological fluids as a mixture of different isoforms, i.e., intact active hormone (hCG), nicked hCG (hCGn), free β subunits (hCGβ), free α subunit (hCGα), β-core fragment (hCGβcf, predominantly detected in urine and containing amino acids 6–40 and 55–92 linked by disulphide bridges) and nicked free β-subunit (hCGβn). Although the measurement of hCG might be useful in a kaleidoscope of clinical conditions, such as diagnosis, monitoring and follow-up of pregnancy-related disorders, prenatal screening and gynecological cancers, the leading application is still the diagnosis of pregnancy, where it can be measured quantitatively either in serum or urine, in the latter case also using qualitative and rapid immunoassays. Since there is still debate as to whether serum or urine tests are to be preferred for establishing a diagnosis of pregnancy, we discuss here the main analytical and clinical aspects of hCG measurement for the diagnosis of pregnancy, highlighting the advantages and limitations of assessing hCG in urine and serum. [Copyright &y& Elsevier]

Abstract: Background: Automated interpretations systems for anti-nuclear antibody (ANA), anti-double stranded DNA antibody (dsDNAab), and anti-neutrophil cytoplasmic antibody (ANCA) assessment by indirect immunofluorescence (IIF) have been recently introduced. The aim of this study was to compare the diagnostic performance of the automated IIF reading system AKLIDES with both traditional visual interpretation of IIF by laboratory experts and confirmatory tests. Methods: Visual and automated autoantibody interpretations of IIF findings using AKLIDES pattern recognition algorithms were performed for ANA on HEp-2 cells (n=182), dsDNAab on Crithidia luciliae (n=44) and ANCA on human neutrophils (n=46). All serum samples tested by IIF for ANCA and dsDNAab were also assessed with the corresponding enzyme-linked immunosorbent assays (ELISAs). Out of the 182 sera tested for ANA by IIF, 116 were also assessed for antibodies to extractable nuclear antigens (ENA) by ELISA and dot immunoassay (DIA). Results: ANA testing showed an excellent agreement between visual and AKLIDES reading (98.9%). The overall agreement of dsDNAab testing on C. luciliae substrate slides was 91.0%, whereas ANCA showed a concordance of 89.1%. There was a remarkable agreement of AKLIDES findings for dsDNAab with confirmatory tests. Conclusion: Visual and automated interpretations of IIF findings for ANA, ANCA, and dsDNAab demonstrated a good agreement when assessing patients with suspected autoimmune diseases. Automated interpretation systems such AKLIDES may improve laboratory efficiency and support standardization of IIF in clinical laboratories. [Copyright &y& Elsevier]