Method for quantifying free hemoglobin, distinct from the hemoglobin-haptoglobin complex, in human serum.

The measurement of free hemoglobin (free Hb) in blood is crucial for assessing the risk of organ damage in patients with hemolytic diseases. However, the colorimetric method, commonly used in clinical practice, does not distinguish between free Hb and the hemoglobin-haptoglobin complex (Hb-Hp) in the blood, instead reflecting the total Hb level. Although size-exclusion high-performance liquid chromatography (SEC-HPLC) can specifically measure free Hb, its clinical use is limited by long assay times. Here, we developed a novel assay method for the rapid quantification of free Hb in serum, distinguishing it from Hb-Hp, using a latex agglutination immunoturbidimetric assay (LATIA). This method could be used to measure free Hb in sera in the range of 1-100 µg/mL in approximately 15 min using an automatic biochemistry analyzer. Using Hb-spiked serum samples from healthy adults, there was a high correlation with Hb levels determined using the newly developed method and SEC-HPLC, indicating a high specificity for free Hb. This novel assay can be used to monitor levels of free Hb in patients with various hemolytic diseases and to design therapeutic strategies based on measured values. However, further studies are required to assess its clinical performance.

Nephelometry vs. Immunoturbidimetry assay: Analytical performance on IgG subclasses.

Interest in measuring immunoglobulin G Subclasses (IgG Subclasses) is increasing as more information is gathered and understanding regarding conditions associated with deficiencies of each IgG Subclass grows. Different methodologies are available for the measurement of IgG Subclasses, but their specificities vary. As a result, laboratories choose the methodology that better suits their routine, but which may not necessarily align with the needs of their population. In addition, the lack of standardization for the quantification of IgG Subclasses causes diagnostic gaps when comparing results provided by different methodologies. Thus, the purpose of our research is to compare the analytical performance of The Binding Site's (TBS) Optilite® human Immunoglobulin G (IgG) and IgG Subclasses Immunoturbidimetry assay, with the Nephelometry method routinely used in our clinical laboratory, Siemens BNII®. Our results show that the Immunoturbidimetry assay appears to be the most reliable to evaluate IgG Subclasses: the sum of IgG Subclasses and Total IgG correlate better than by Nephelometry. Although these methodologies share a similar principle, the comparison of results appears to be compromised. Therefore, prior to switching methodologies, further studies should be conducted to assess which methodology could be better applied to specific populations. It is also essential to standardise IgG Subclasses assays to reduce discrepancies that arise from comparing results.

Unexpected discovery of CRP analytical interference: A case report.

OBJECTIVES: Immunoturbidimetric assays are sensitive techniques in clinical biology that may be subjected to matrix effects, hook effects or aspecific reactions. Among these, large quantities of immunoglobulins can distort the intensity of the detected signal. This study illustrates the deleterious effect of analytical interference on clinical patient management, and assesses the practical relevance of a recently proposed algorithm for interference investigation. METHODS: Determination of C-Reactive Protein (CRP) concentration by liquid immunoprecipitation on latex particles coated with mouse anti-CRP monoclonal antibodies, rabbit anti-CRP polyclonal antibodies, by solid phase immunochemistry or by enzymatic assay. RESULTS: During the follow-up of a 75-year-old patient suffering from multiple chronic diseases in the Internal Medicine Department of Toulouse University Hospital, a severe infection was suspected facing a CRP plasma value over 700 mg/L while he was in remission of an indolent marginal zone lymphoma. Because of the absence of clinical signs of infection, an interference in the liquid immunoprecipitation CRP assay was suspected. The hypothesis of an interference due to anti-mouse autoantibodies was ruled out because of normal results for other immunoassays using different types of antibodies. Moreover, no interference was observed using solid phase immunochemistry assay. Protein electrophoresis and immunofixation documented a relapse of lymphoma along with the presence of abnormal monoclonal immunoglobulins interfering with CRP measurement. CONCLUSION: The interpretation of common clinical biochemistry parameters such as CRP can be difficult owing to analytical interferences. Reviewing all the pharmaco-clinico-biological data and collaboration with clinicians is of critical importance for optimal patient management.

A metal-organic framework signaling probe-mediated immunosensor for the economical and rapid determination of enrofloxacin in milk.

Ensuring the safety of animal-derived foods requires the reliable and swift identification of enrofloxacin residues to monitor the presence of antibiotics. In this regard, we synthesized, tuned, and investigated the optical properties of a bimetallic metal-organic framework (Ce/Zr-UiO 66). The investigation was facilitated by employing a polydopamine-coated pipette tip with high adsorption efficiency, serving as an immunoreactive carrier. Subsequently, an immunofunctionalized variant of Ce/Zr-UiO 66, referred to as Ce/Zr-UiO 66@ Bovine serum albumin-enrofloxacin, was developed as an optical probe for the rapid and sensitive identification of enrofloxacin across a variety of samples. The method can accurately detect enrofloxacin at concentrations as low as 0.12 ng/mL, with a determination time of under 15 min; furthermore, it demonstrates exceptional efficacy when applied to food, environmental, and clinical samples. The implementation of this methodology offers a valuable means for cost-effective, rapid, and on-site enrofloxacin determination.

Abbott D-dimer assay: analytical performance and diagnostic accuracy in management of venous thromboembolism.

This study aimed to assess analytical characteristics and diagnostic accuracy in management of venous thromboembolism (VTE) in the Emergency Department (ED) of the Abbott D-dimer assay applied on the Alinity c clinical chemistry analyzer (Abbott Laboratories, Chicago, IL) compared to the INNOVANCE D-dimer assay (Siemens Healthineers, Marburg, Germany). Precision was determined at three concentration levels following the CLSI EP15-A3 protocol. Method comparison and diagnostic accuracy were assessed using samples obtained from 85 patients who were referred for diagnostic imaging and D-dimer testing due to clinically suspected VTE. Within-run coefficients of variation (CVs) were 3.0%, 0.5% and 0.5% at D-dimer concentrations of 0.54, 1.42 and 2.68 mg/L FEU, while respective between-run CVs were 2.0%, 3.4% and 2.7%, hence fulfilling the desirable biological variation criteria for imprecision (<12.6%). Passing-Bablok regression analysis yielded a small proportional difference between the two compared assays (y = 1.09 (95% confidence interval (CI): 1.01-1.18) x + 0.09 (95%CI: -0.09 to 0.16)), while Bland-Altman analysis showed significant negative absolute (-0.6 mg/L FEU, 95%CI: -0.9 to -0.3) and relative mean bias (-14.1%, 95%CI: -20.3 to -7.9). Spearman's ρ was 0.979 (95%CI: 0.967-0.986). Inter-assay agreement relative to the cut-off was 92% (kappa coefficient = 0.547 (95%CI: 0.255-0.839)). Diagnostic sensitivity, specificity, positive and negative predictive values of the Abbott assay were 100%, 9.2%, 25.3% and 100%, respectively, compared to the following data for the INNOVANCE assay: 95.0%, 15.4%, 25.7% and 90.9%. Abbott D-dimer assay has shown excellent analytical precision, high comparability with the INNOVANCE D-dimer and high NPV at manufacturer's cut-off.

Determination of cystatin C reference interval for children in Croatia.

Introduction: Cystatin C is considered an early marker of kidney damage. The aim was to determine the reference interval in children since this information was not available from the test manufacturer. Materials and methods: Included were children aged 0 to 18 years undergoing routine check without history of any renal disease. Cystatin C was measured by the immunoturbidimetric method, and creatinine by the enzymatic method on a Cobas c501 analyzer (Roche Diagnostics, Manheim, Germany). Reference intervals were determined according to the CLSI C28-A3 guidelines using a robust method and a nonparametric percentile method, depending on the sample size. The Schwartz's formula was applied to estimate glomerular filtration (eGFR) from cystatin C. Results: The cystatin C reference interval for children aged 1-18 years (N = 204, median 8 years) was from 0.61 mg/L (90% CI: 0.53 to 0.64) to 1.08 mg/L (90% CI: 1.07 to 1.14). Differences according to sex were not found. For children aged 0-1 years (N = 29, median 5 months), the reference interval was from 0.60 mg/L (90% CI: 0.48 to 0.72) to 1.49 mg/L (90% CI: 1.36 to 1.61). The sample size was too small to test the difference according to sex. The eGFR was 76 (70-88) mL/min/1.73m2 for males and 83 (74-92) mL/min/1.73m2 for females. Conclusion: The cystatin C reference intervals for Croatian pediatric population according to age were determined. The cystatin C concentrations in children reach adulthood values after the first year. The cystatin C Schwartz's formula is applicable for eGFR calculation in children.

Validation of the fCAL turbo immunoturbidimetric assay for measurement of calprotectin in porcine and bovine fecal samples.

The concentration of calprotectin in feces is a well-studied marker of gastrointestinal inflammation in humans. However, little is known about fecal calprotectin in farm animals. In this work, we have validated an immunoturbidimetric method for fecal calprotectin (Bühlmann fCAL® turbo assay, Schönenbuch, Switzerland) in porcine and bovine fecal samples. Linearity was evaluated by serial dilution (R2 > 0.97 was obtained for both species). Accuracy was assessed by a recovery study, with results between 80 and 120% for low, medium, and high samples in both species. Intra- and inter-assay variability was <20%. Limit of detection was 6.4 µg/g in pig and 5.3 µg/g in cow. Limit of quantification was 13.4 µg/g (pig) and 11.1 µg/g (cow). Additionally, clinical validation has been included to evaluate the ability of the assay to detect inflammatory status in the intestine under different management conditions. In experiments with porcine, it was found that piglets treated with ZnO had lower concentrations of fecal calprotectin. In a second experiment in bovine, calves with diarrhea had higher concentration of fecal calprotectin. The Bühlmann fCAL® turbo assay is suitable for measurement of calprotectin in porcine and bovine fecal samples. Moreover, fecal calprotectin could be a good biomarker of intestinal inflammation in both species.

Potential interference of in vitro carbamylation on C-reactive protein laboratory measurement.

Carbamylation is a nonenzymatic post-translational modification observed during the reaction between cyanate and amino acids and/or proteins that may occur during some pathologies such as chronic kidney disease. Evidence suggests that carbamylation may interfere with the quantification of some analytes measured using immunoturbidimetric assays. C-reactive protein (CRP) is an inflammatory response protein that is commonly quantified through immunoturbidimetry in clinical laboratories. Because the presence of modified proteins in serum can lead to impaired quantification, this study aimed to verify the impact of in vitro carbamylation on the measurement of CRP in a CRP standard solution and serum pool. The samples were incubated with 150 nM, 150 µM, or 150 mM potassium cyanate (KOCN) or 20, 100, or 500 mg/dL urea at 37 °C for 24 h. CRP concentrations were measured using an immunoturbidimetric assay. The results showed a 61%-72% decrease in the CRP detection rate after incubation with KOCN. Incubation with urea resulted in a 0.7%-8% lower CRP detection rate. The results of this study indicate that high concentrations of cyanate can lead to falsely decreased CRP levels, as measured by immunoturbidimetry.

Validation of new automated turbidimetric immunoassays for the measurement of haptoglobin and inter-α-trypsin inhibitor heavy chain H4 specific for the bovine species.

BACKGROUND: Good strategical programs are required for the early detection of disease even in the absence of evident clinical signs, which is crucial in satisfying animal welfare. Haptoglobin (Hp) and inter-α-trypsin inhibitor heavy chain H4 (ITIH4) are acute phase proteins and good biomarkers of early inflammation in cattle, with plasma levels that significantly increase after injury or infection. OBJECTIVES: We aimed to develop and validate two new immunoturbidimetric methods for Hp and ITIH4. METHODS: Species-specific antibodies were obtained and used to develop the immunoassays. For the Hp assay, antibodies were fixed to latex microparticles to enhance detection. The immunoassays were set up in an automated analyzer to carry out validation studies. Reference intervals were calculated using Reference Value Advisor. RESULTS: The Hp immunoturbidimetric method had a linear analytical range up to 0.40 mg/mL. The limit of detection (LoD) was 0.005 mg/mL, and the limit of quantification (LoQ) was 0.007 mg/mL. Total imprecision was less than 7%. Comparison with ELISA and single radial immunodiffusion (SRID) showed good correlation, whereas the comparison with the colorimetric method showed constant and proportional differences. The ITIH4 immunoassay showed linearity up to 5 mg/mL, and the LoD was 0.002 mg/mL. Total imprecision was less than 6%. Method comparison showed a good correlation with single radial immunodiffusion, both methods being equivalent. Bilirubin, triglycerides, and hemoglobin presented no interference in any of the assays. Reference intervals were 0.007-0.017 mg/mL for Hp and 0.2-0.7 mg/mL for ITIH4 in dairy cows 10 days before parturition. CONCLUSIONS: Immunoturbidimetric methods developed for Hp and ITIH4 can measure basal and increased levels of these proteins, showing adequate precision, accuracy, and robustness.

Cystatin C assay validation using the immunoturbidimetric method to evaluate the renal function of healthy dogs and dogs with acute renal injury.

Background and Aim: Acute kidney injury (AKI) is associated with a grave prognosis. A clinical assessment of kidney function can be performed based on the glomerular filtration rate (GFR). Cystatin C (CysC) can indicate the GFR or kidney function and its measurement is currently performed using immunological methods such as nephelometry, immunoturbidimetry, and enzyme-linked immunosorbent assays in human medicine. However, these techniques are not specific for use in veterinary medicine. This study aimed to validate an immunoturbidimetric assay for serum CysC (sCy) in dogs, determine the sCy reference intervals for healthy dogs, evaluate sCy stability in serum samples, and compare sCy with serum creatinine (sCr) in healthy dogs and dogs with AKI. Materials and Methods: Forty-three dogs were divided into a control group (n = 19) and an AKI group (n = 24). An immunoturbidimetric method including commercially available human CysC calibrated with canine CysC was used to evaluate canine serum samples. Results: An average recovery of 97% was observed for canine serum samples. The reference interval for CysC in healthy dogs was 0.57-1.29 mg/L. The sCy concentration in dogs with AKI was significantly higher (2.82 ± 1.46 mg/L) than in healthy dogs (0.93 ± 0.18 mg/L). Statistical analysis confirmed a strong correlation between sCy and sCr (r = 0.94; p < 0.05) in dogs with AKI. Conclusion: The immunoturbidimetric method of evaluating sCy yielded satisfactory results and can be used for canine samples when a species-specific calibrator is used. Furthermore, sCy is a reliable marker of renal dysfunction in dogs. It is best to store samples for sCy evaluation at temperatures between 4°C and 8°C.

Analytical performance of a new immunoturbidimetric D-dimer assay and comparison with available assays.

BACKGROUND: The routine D-dimer quantification to exclude venous thromboembolism has led to the development of many assays, the usefulness of which depends on their reliability and performance. OBJECTIVE: We evaluated the analytical performances of the immunoturbidimetric Yumizen G DDi 2 assay (HORIBA Medical, Montpellier, France) performed on the Yumizen G800 analyzer and compared it with other available D-dimer assays. METHODS: Within-run and between-run imprecision were evaluated using low- and high-level quality-control plasma samples. Interference due to hemolysis, icterus, lipemia, rheumatoid factor (RF), or heterophilic antibodies (human antimouse antibodies [HAMAs]) was evaluated by spiking plasma samples with hemolysate, bilirubin, Intralipid, RF, or HAMAs. The measurements obtained with the different D-dimer assays were compared using Passing-Bablok regression analysis and Bland-Altman plot method, using fresh citrated plasma samples collected from 66 consecutive routine patients with a wide range of D-dimer concentrations. RESULTS: Within- and between-run variation coefficients for the Yumizen G DDi 2 assay ranged from 1.7% to 5.8% and from 2.8% to 5.5%, respectively. Hemolysis and icterus did not have any effect up to 10 g/L hemoglobin and 300 mg/L bilirubin. Lipemia seemed to generate an underestimation of D-dimer concentration when the Intralipid concentration was >5 g/L. RF and HAMAs did not have any effect. The Passing-Bablok and Bland-Altman analyses showed small differences with other available D-dimer assays, which were more pronounced with increasing values. CONCLUSIONS: Its analytical performances and main technical features indicate that the new Yumizen G DDi 2 assay is suitable for the rapid quantification of D-dimer in clinical hemostasis laboratories.

Reference interval for urinary neutrophil gelatinase-associated lipocalin in healthy adults in Jiangsu region in Eastern China: a multicenter study.

Aim: We explored the concentrations of urinary neutrophil gelatinase-associated lipocalin (NGAL) in healthy adults in the Jiangsu region in Eastern China and established a reference interval using latex-enhanced immunoturbidimetry to provide important guidelines for the interpretation and application of urinary NGAL in clinical practice. Methods: In total, 1970 eligible subjects from four regions were included in this study. The urinary NGAL levels were measured using an AU5800 automatic biochemical analyzer with its matched reagents. The urinary NGAL reference interval was established using the one-sided percentile method (95th percentile). Results: The urinary NGAL data were non-normally distributed. The urinary NGAL levels were not significantly different by sex or age. Therefore, the urinary NGAL reference interval in healthy adults in the Jiangsu region in Eastern China was <87.5 ng/ml (95th percentile of the upper limit). Conclusion: Urinary NGAL reference interval will play an important role in promoting the clinical value of urinary NGAL.

Assessment of C-Reactive Protein Level in Oral Submucous Fibrosis and Oral Squamous Cell Carcinoma Patient.

BACKGROUND: Potentially malignant disorders are highly prevalent in India. In this study, we assessed C-reactive protein (CRP) levels in patients with oral submucous fibrosis (OSMF) and oral squamous cell carcinoma (OSCC). METHODOLOGY: Sixty-four patients (OSMF and OSCC) were undertaken and were classified into 3 groups, OSMF patients (Group I, 34), OSCC (Group II, 30), and healthy controls (Group III, 26). Immunoturbidimetry method was used for the estimation of CRP levels. RESULTS: Maximum cases in Group I was seen in the age group 40-60 years (males-10, females-3), Group II in the age group 40-60 years (males-11, females-5) and Group III (males-5, females-6). The mean CRP level in Group I was 6.12 ± 4.5 mg/l, in Group II was 28.4 ± 21.5 mg/l, and in Group III was 3.15 ± 2.19 mg/l. The difference was significant (P < 0.05). CONCLUSION: Authors found that OSMF and oral cancer patients had increased CRP levels as compared to healthy subjects.

Impact of albumin carbamylation on immunoturbidimetric measurement of urinary albumin.

Urinary albumin is one of the main markers used in clinical practice to assess kidney damage. It is usually measured in laboratories through immunological assays, but these assays may not detect molecules with conformational changes, such as carbamylated albumin/proteins. Therefore, this study aimed to investigate the impact of albumin carbamylation on the measurement of albuminuria by an immunoturbidimetric assay. The addition of the carbamylating agent to PBS buffer and urine pool promoted a lower quantification of albumin measured by the immunoturbidimetric method, indicating that this process may be responsible for an underestimation of the results in clinical practice.

Technical Note: Comparative Study of Three Different Fecal Calprotectin Immunoassays: TriCAL Study.

OBJECTIVE: Calprotectin is a biomarker of gastrointestinal inflammation and disease activity. We aimed to evaluate the performance of a new fecal calprotectin (FC) test (CALiaGold®) in comparison with two other rapid FC immunoassays. METHODS: Fecal samples were analyzed with all three FC tests. Correlation between the FC tests was assessed. Agreement to discriminate FC-positive samples was also evaluated according to the manufacturers' cut-off values. RESULTS: A correlation coefficient of over 0.800 was found in all comparisons. Lower deviation of linearity was observed between immunoturbidimetric assays. Agreement on FC-positive sample detection was reduced in comparisons with the immunochromatographic assay. CONCLUSIONS: The CALiaGold® test showed good performance for FC assessment. Better correlation and agreement between immunoturbidimetric assays were confirmed.

Verification of automated latex-enhanced particle immunoturbidimetric D-Dimer assays on different analytical platforms and comparability of test results.

INTRODUCTION: The aim of the study was the analytical verification of automated latex-enhanced particle immunoturbidimetric (LPIA) D-Dimer assay INNOVANCE D-dimer on Sysmex CS-5100 and Atellica COAG 360 analysers, and HemosIL D-dimer HS500 on ACL TOP 550, as well as the comparison with the enzyme-linked immunofluorescent assay (ELFA) on the miniVidas analyser. MATERIALS AND METHODS: Verification included assessment of within-run and between-run precision, bias, measurement uncertainty (MU), verification of the cut-off, method comparison between all assessed assays, and the reference commercial ELFA VIDAS D-Dimer Exclusion II. RESULTS: Within-run coefficients of variations (CVs) ranged from 1.6% (Atellica COAG 360) to 7.9% (ACL TOP 550), while between-run CVs ranged from 1.7% (Sysmex CS-5100) to 6.9% (Atellica COAG 360). Spearman's rank correlation coefficients were > 0.99 between LPIAs and ≥ 0.93 when comparing ELFA with LPIA. Passing-Bablok regression analysis yielded constant and proportional difference for comparison of ACL TOP 550 with both Sysmex CS-5100 and Atellica COAG360, and for miniVidas with Atellica COAG360. Small proportional difference was found between miniVidas and both Sysmex CS-5100 and ACL TOP 550. Calculated MUs using D-dimer HS 500 calibrator were 12.6% (Sysmex CS-5100) and 15.6% (Atellica COAG 360), while with INNOVANCE D-dimer calibrator 12.0% (Sysmex CS-5100), 10.0% (Atellica COAG 360) and 28.1% (ACL TOP 550). Excellent agreement of results was obtained, with occasional discrepancies near the cut-off. The cut-off (0.5 mg/L FEU) was confirmed. CONCLUSIONS: The obtained results prove satisfactory analytical performance of LPIAs, their high comparability and almost equal discriminatory characteristics, suggesting them as a valid alternative to ELFA.

Detection of monoclonal free light chains by immunofixation electrophoresis and isoelectric focusing - comparison with the quantitative method of determination.

The study aimed to investigate free light chain (FLC) monoclonality in patients with an abnormal free kappa/lambda ratio (FLC ratio). Seventy serum samples with abnormal FLC ratio were examined using an immunoturbidimetry (Binding Site, SPA) and the two different enzyme-linked immunosorbent assays (1. Sebia diagnostic kit; 2. in house methods), the monoclonal or oligoclonal bands of (FLC) by immunofixation electrophoresis (IE) and isoelectric focusing followed by affinity immunoblotting (IEF/AIB). The reference interval was calculated by non-parametric percentile method. 5.7% of samples examined by IE were suspected of monoclonal character of FLCs, but subsequently monoclonality was refuted by more sensitive IEF/AIB method; 7%, resp. 2.9% of samples showed FLC kappa, resp. FLC lambda oligoclonal character of bands. A statistically significant dependence was found between FLC ratio (Sebia) and FLC ratio (SPA), rs = 0.510, p = .001. Kappa statistic evaluated a fair conformity between the FLC ratio (Sebia) and IEF/AIB (kappa = 0.468) and between FLC ratio (in house) and IEF/AIB (kappa = 0.300). The verified reference interval for FLC ratio (Binding Site) is between 0.35 and 2.18. The IEF/AIB is the most sensitive method to discriminate between monoclonal and oligoclonal bands of FLC. The Binding Site and Sebia diagnostic kits do not give consistent results. The Binding Site diagnostic kit provides more results above reference interval of FLC ratios. For routine decision on monoclonality of the FLC ratio (SPA) it is advisable to use a verified reference interval.

Validation of suPAR turbidimetric assay on Cobas® (c502 and c702) and comparison to suPAR ELISA.

suPAR is a plasma marker of chronic inflammation, and an elevated suPAR is consistently associated with worse outcome in a variety of clinical conditions. Quantification of suPAR is useful for determining patient risk in triage, but there is no fast automatized method for quick determination of suPAR. We developed and validated a rapid latex particle-enhanced turbidimetric immunoassay for quantification of plasma suPAR on the c502 and the c702 Roche Cobas® 8000 measurment systems. The turbidimetric assay was validated against the suPARnostic® ELISA (ViroGates, Denmark). This validation demonstrates suPAR can be analysed by turbidimetry giving very similar results (<15% difference) compared to the ELISA method and the observed correlations (n = 103) were strong, r > 0.95. Roche Cobas® 8000 instruments demonstrated repeatability and repoducibility, CV % at 3.4-4.1 and 5.7-11.4, respectively. The estimated limit of detection was 1.30 µg/L and 1.31 µg/L for the Cobas® c502 and c702, respectively. Dilution tests showed linearity of suPAR from 1.8 to 26.5 µg/L. The acceptable concentrations of Bilirubin, Intralipid and Hemoglobin, were 350 µmol/L, 3.3 g/L and 1.4 g/L, respectively. suPAR can be quantified reproducibly within 10 min using a turbidimetry assay. This assay is faster than ELISA with similar results, making it suitable for clinical routine analysis.

Performance evaluation of the hook effect of five immunoturbidimetric kits for the detection of specific proteins / 国际检验医学杂志

Objective To evaluate the performance of hook effect of five immunoturbidimetric kits for the detection of specific proteins on biochemical analyzers.Methods Five immunoturbidimetric kits with higher market share that came from Beijing BSBE (A), Sichuan maccura (B), Shenzhen Mindray (C), Ningbo Medical System (D) and Beijing Leadman (E) were used to determine six specific proteins.A series of concentration gradient samples were prepared and tested to compare the performance of hook effect from different manufactures′kits when the analytical measurement ranges were known.Results In the five kits, the upper limits of the safe range of antigen excess about ASO, hs-CRP andβ2-MG were relatively higher in B and C.No hook effect occurred at the approximate concentration of 10 000IU/mL, 1 000mg/L and 226mg/L respectively.The highest upper limits for CysC were C and E kits, and both were greater than 112mg/L.The upper limits of the safety range for other manufacturers were more than 700mg/L about RBP except for D.The maximum upper limit of mALB was D.Hook effect did not appear at the concentration of 43 560mg/L approximately.Conclusion Different manufactures′immunoturbidimetric kits have different hook effect performance.The laboratories should verify the hook effect performance before using the kits, and select the most suitable kit to prevent hook effect.

Analytical Performance of INNOVANCE Free Protein S Antigen on Sysmex CS-5100

BACKGROUND: Protein S deficiency is a common cause of thrombophilia. Free protein S has been suggested as one of the best screening tests for this deficiency. We evaluated an immunoturbidimetric free protein S reagent, INNOVANCE Free Protein S Antigen (Free PS Ag; Siemens Healthcare Diagnostics, Germany), using a CS-5100 coagulation analyzer (Sysmex, Japan). METHODS: The performance of INNOVANCE Free PS Ag was evaluated according to the CLSI guidelines. Precision, linearity, and verification of reference intervals were examined. The INNOVANCE Free PS Ag was also compared by the STA-Liatest Free Protein S immunoturbidimetric assay (Diagnostica Stago, France). RESULTS: The repeatability and within-laboratory imprecision of INNOVANCE Free PS Ag were 0.8% CV and 2.0% CV at the normal level, and 1.3% CV and 2.3% CV at the abnormally low level, respectively. This assay showed linearity from 4.0% to 151.9% (correlation coefficient r=1, P < 0.0001). Reference intervals for males and females were verified as acceptable. INNOVANCE Free PS Ag was comparable with STA-Liatest Free Protein S with a very high correlation (r=0.935, P < 0.0001). The results for the INNOVANCE antigen were higher. CONCLUSIONS: The INNOVANCE Free PS Ag on a Sysmex CS-5100 coagulation analyzer has excellent analytical performance and is comparable with the STA-Liatest Free Protein S assay.