Commercial Control Materials Research Articles

A high performance liquid chromatography fluorescence method for the analysis of both pyridoxal-5-phosphate and thiamine pyrophosphate in whole blood

Background and aimsThe active coenzymes of the water soluble vitamins B1 and B6 (thiamine pyrophosphate (TPP) and pyridoxal-5-phosphate (P5P) respectively) play an important role in numerous bodily functions. The simultaneous analysis of both these analytes is limited to either mass spectrometry based methods or commercial kit suppliers. In this study we developed a novel method for analysis of both TPP and P5P by fluorescence detection. MethodsBriefly, whole blood samples are precipitated by trichloroacetic acid, and P5P and TPP are both derivatised before separation on a C18-PFP column. The new assay’s performance was compared against a recent cycle from an external quality assurance program (RCPAQAP) and the current only existing commercial kit (n = 76). ResultsLinearity for both analytes was above 0.99 (r2) up to a concentration range of: 4000 nmol/L (P5P) and 2000 nmol/L (TPP). Precision of the method (intra-day and inter-day) compared against commercial quality control material was below 6% (coefficient of variation). Recovery of both compounds exceeded 90%. Accuracy of the protocol displayed satisfactory results in proficiency testing and had an acceptable level of agreement with the existing current kit method. ConclusionsOverall, this method provides an economical alternative in routine clinical diagnostic laboratories wishing to perform P5P and TPP analysis.

An automated workflow approach for the analysis of flavin adenine dinucleotide by HPLC with internal standard

Flavin adenine dinucleotide (FAD) is an active coenzyme of vitamin B2 involved in oxidation and reduction reactions. In this study we have developed a fully automated method for the analysis of FAD by fluorescence detection. FAD is extracted from whole blood samples by trichloroacetic acid, with diethyl ribityl isoalloxazine used as an internal standard. Linearity for FAD was above 0.99 (r2) up to a concentration range of 1000 nmol/L. Precision of the method (intra-day and inter-day) compared against commercial quality control material was below 8% (coefficient of variation) with recovery of FAD exceeding 90%. Accuracy of the protocol was compared against a previous cycle from an external quality assurance program (RCPAQAP) (n = 12) with satisfactory agreement. Overall, this method has increased laboratory workflow and reduced manual labour required in performing FAD analysis.

Preparation of In-House Quality Control Human Serum for Urea and its Use in Clinical Chemistry.

Quality control materials play a vital role in the laboratory internal and external quality assessment program. However, Ethiopia and other developing countries are challenged by the unavailability and high cost of commercial control material. Therefore, preparing in-house quality control human serum will be a cost-effective way to obtain QC material for use in poor settings in a country like Ethiopia. To prepare urea in-house control human serum and scientifically evaluate it with commercially available sera already in use in the clinical chemistry laboratory of the Ethiopian Public Health Institute. The urea in-house quality control human serum was prepared as per ISO Guide 80, a guideline document protocol from 57 participants' normal serum specimens at the Ethiopian Public Health Institute clinical chemistry laboratory. The quality control material was analyzed on a fully automated chemistry analyzer (Cobas 6000). The initial 20 values were used for calculation of means, standard deviation (SD) and coefficient of variation (CV). Results were compared with those of commercially available lyophilized human sera. The average concentrations of urea were found to be near the middle of the physiological range of healthy subjects and the in-house serum could be a good substitute for the commercial serum of normal range. The prepared in-house quality control human serum is stable for about three months without any alterations in the concentration of urea. Well prepared in-house quality control human serum is a good substitute for commercially available control serum of normal range, especially in a developing country like Ethiopia.

Presepsin: co je nutné vědět pro korektní interpretaci

Presepsin (soluble CD14 subtype) is a new biomarker of infection and sepsis. Correct interpretation is based on the knowledge of analytical reliability, biological variation, decision limits, and diagnostic effectivity.The aim of the study was to verify analytical precision of presepsin measurements, to assess biological variation in healthy subjects, to verify reference and decision limits, to assess diagnostic effectivity, and to compare data with commonly used septic biomarkers - procalcitonin (PCT), CRP and interleukin 6 (IL6).Analyti-cal precision (repeatability and intermediate precision) was estimated by repeated measurements of commercial control materials. Biological variation was evaluated in a group of 20 healthy volunteers in a 7-week experi-ment. Reference ranges were extracted from the literature and compared with data from healthy subjects.Precisions of presepsin measurements were 2.0-4.0 % (“within-run”) and 6.1-9.5 % (“between-run”). Intraindividual biological variation of presepsin was 22.3 %, interindividual variation 20.8 %. Index of individuality was 1.07, reference change value (RCV - critical difference) was 72 %. Upper reference limit was around 180 ng/l.Ana-lytical quality of presepsin measurement is suitable for clinical use. Biological variation parameters enable the use of reference limits, upper reference limit of presepsin is around 180 ng/l. None of the tested biomarkers has universal cut-off value, multiple biomarkers are needed and repeated measurements are advisable.

Atellica UAS 800 urine sediment analyzer compatibility with commercial quality control materials and urine preservative tubes

Atellica UAS 800 urine sediment analyzer compatibility with commercial quality control materials and urine preservative tubes

Verification of the Performance of a Fully Automated Coagulation Analyzer and Ongoing Assessment of External Quality Assurance Results in an Academic Laboratory in South Africa.

Verification of the performance of analytical platforms is indicated prior to adoption of new Technology for patient sample analysis. Acceptance criteria for the performance of coagulation analytical platforms are not always readily available and is complicated by the multiple assays and test principles in this section of the clinical laboratory. Coagulation samples are also prone to pre-analytical, post-sample collection variables potentially interfering with accuracy analysis. This verification study assessed the accuracy of the automated STAGO STA-R Max® coagulation analyzers by means of a comparison study of results obtained on the previously validated STAGO STA-R Evolution® analyzer for 22 coagulation parameters on 40 individual patient samples for each parameter. Within- and between- run reproducibility on commercial control material, carry-over from abnormal to normal samples and the interference of bilirubin, hemoglobin and lipids on the chromogenic analytical channel were also assessed. Ongoing evaluation of the analyzer performance was assessed by External Quality Assurance (EQA) scheme participation. The reproducibility (precision) on 2 levels (Normal and Pathological) commercial control material was acceptable with co-efficient of variance (CV) results below the manufacturer target % CVs. The correlation study demonstrated accuracy of results obtained on the analyzers for all parameters except for D-dimers and coagulation Factor VII. Subsequent EQA performance for these two parameters were however satisfactory. Interference from bilirubin, hemoglobin and lipids did occur in the chromogenic channel. No clinically significant carry over from abnormal to normal samples were observed. The performance of the STAGO STA-R Max® analyzer is acceptable across the full coagulation test repertoire with the exception of the von Willebrand activity assay. Participation in EQA scheme assessments will be an integral part of ongoing monitoring of the performance of this automated analyzer.

Comparison of two commercial quality control sera for adrenocorticotropin (ACTH) used in Elecsys® immunoassay system.

The purpose of our study was to investigate whether the storage time and temperature of internal quality control (IQC) material influence the result of ACTH in IQC measurements. Five levels of IQC materials from two manufacturers were tested through the precision of ACTH, the three freeze/thaw cycles, and the storage time and temperature to evaluate the stability of IQC material. All commercial control materials were simultaneously tested three times a day for five consecutive days. Total precision of three levels of Bio-Rad IQC sera was 13.93%, 16.45%, and 15.98%, respectively, but repeatability was <2%. The concentration of ACTH decreased by 30%-50% after 3 freeze/thaw cycles. At room temperature, the concentration of ACTH from 3 levels decreased by 16.60%, 17.98%, and 17.20%, respectively, after 0.5hours, and 70.54%, 74.36%, and 72.03%, respectively, after 4hours. However, after 2hours of storage at 4°C, the decline in the measured ACTH IQC was 8.04%, 11.84%, and 10.11%, respectively. Total precision of Roche IQC was 1.17% and 1.08%, respectively. After 3 freeze/thaw cycles, the concentration of ACTH decreased <5%. After 4hours, the change of ACTH still steadied within 5% both at the room temperature and at 4°C. Roche is a better choice for ACTH of IQC material in Elecsys® immunoassay system in our study. If Bio-Rad control materials be used in Elecsys® immunoassay system for ACTH IQC testing material, it should be stored at 4°C and testing should be completed within 1hours.

Verification of the Heska Element Point‐of‐Care blood gas instrument for use with venous blood from alpacas and llamas, with determination of reference intervals

The Heska Element POC ("EPOC") is a blood gas instrument intended for use with canine, feline, and equine whole blood; no verification for use with camelid specimens has been reported. Using camelid specimens and commercial quality control materials (QCM), we investigatee EPOC analytical performance and establish EPOC camelid reference intervals (RIs). Camelid blood (n=124) was analyzed using the EPOC (pH, pCO2 , pO2 , HCO3 , base excess, SO2 , sodium, potassium, chloride, ionized calcium, TCO2 , anion gap, HCT, HGB, glucose, lactate, and creatinine); plasma was analyzed using a Roche Cobas c501 (sodium, potassium, chloride, TCO2 , anion gap, glucose, and creatinine). Method comparison data were assessed using Pearson's correlation, Passing-Bablok regression, and Bland-Altman plots. EPOC precision was evaluated using QCM and camelid blood. For all measurands except anion gap, the EPOC vs Cobas instrument correlation was r>.85. Except for pO2 and pCO2 , EPOC precision (QCM and blood) ranged from a repeatability CV <1%-6.3%. Mild constant bias for chloride, glucose, TCO2 , anion gap, and creatinine, and mild proportional bias for chloride, glucose, and anion gap were present. The total error (QCM data) for the EPOC instrument was below the ASVCP-recommended allowable total error. Alpacas had higher potassium and lactate, while llamas had higher creatinine, sodium, chloride, ionized calcium, pO2 , and SO2 . Statistical RIs based on alpaca (n=74-96) and llama data (n=12-17) are reported descriptively. The EPOC analyzer shows good performance with camelid blood. A lack of complete agreement with automated chemistry analyzers highlights the importance of interpreting patient data using instrument-specific RIs.

GENE DIVERSITY IN GREVILLEA POPULATIONS INTRODUCED IN BRAZIL AND ITS IMPLICATION ON MANAGEMENT OF GENETIC RESOURCES

ABSTRACT We describe isoenzymes variability in six populations of Grevillea robusta from a provenances and progenies test established in a randomized block design with five plants per replication in Southern Brazil. The population genetic structure was examined by using biochemical markers in 5-year old trees, specifically at MDH-3, PGM-2, DIA-2, PO-1, PO-2, SOD-1, and SKDH-1 loci. The northern provenances (Rathdowney and Woodenbong) showed a strong divergence in relation to the average of provenances when alleles per locus (Ap), allele richness (Rs), Nei's gene diversity (H), and inbreeding coefficient (f) were considered. Inbreeding in varying degrees was detected. The commercial control showed the highest inbreeding coefficient, (f = 0.4448), whereas the provenance average was f = 0.2306, possibly due to insufficient sampling of populations in their origin (Australia). Despite its restricted natural range, a positive correlation between genetic divergence and geographic distance among original populations was detected. Genetic distance and cluster analyses based on the Bayesian model revealed three distinct provenance groups: 1) Rathdowney-QLD and Woodenbong-QLD; 2) Paddy's Flat-NSW; and 3) Mann River-NSW, Boyd River-NSW and the commercial control (material used in Brazil). The grouping of the control to both Mann River-NSW and Boyd River-NSW provenances suggests that the northern provenances have the highest potential for genetic improvement of wood productivity in Brazil, due to their high genetic diversity and low inbreeding coefficient.

Nanostructured Polymeric Materials with Protein-Repellent and Anti-Caries Properties for Dental Applications.

Dental caries is prevalent worldwide. Tooth cavity restorations cost more than $46 billion annually in the United States alone. The current generation of esthetic polymeric restorations have unsatisfactory failure rates. Replacing the failed restorations accounts for 50–70% of all the restorations. This article reviewed developments in producing a new generation of bioactive and therapeutic restorations. This includes: Protein-repellent and anti-caries polymeric dental composites, especially the use of 2-methacryloyloxyethyl phosphorylcholine (MPC) and dimethylaminododecyl methacrylate (DMAHDM); protein-repellent adhesives to greatly reduce biofilm acids; bioactive cements to inhibit tooth lesions; combining protein-repellency with antibacterial nanoparticles of silver; tooth surface coatings containing calcium phosphate nanoparticles for remineralization; therapeutic restorations to suppress periodontal pathogens; and long-term durability of bioactive and therapeutic dental polymers. MPC was chosen due to its strong ability to repel proteins. DMAHDM was selected because it had the most potent antibacterial activity when compared to a series of antibacterial monomers. The new generation of materials possessed potent antibacterial functions against cariogenic and periodontal pathogens, and reduced biofilm colony-forming units by up to 4 logs, provided calcium phosphate ions for remineralization and strengthening of tooth structures, and raised biofilm pH from a cariogenic pH 4.5 to a safe pH 6.5. The new materials achieved a long-term durability that was significantly beyond current commercial control materials. This new generation of bioactive and nanostructured polymers is promising for wide applications to provide therapeutic healing effects and greater longevity for dental restorations.

Performance characteristics of the Beckman Coulter UniCel DxI 800 TSH (3rd IS) assay

IntroductionBeckman Coulter recently reformulated their commercial TSH assay with primary calibration to the World Health Organization 3rd TSH international standard. An extensive evaluation of the performance characteristics for this assay was completed. MethodsIntra-day and inter-day precision was evaluated using 3 concentrations of commercial quality control material. Linearity, reportable range, stability, sensitivity and susceptibility to common inferences were determined using pooled patient specimens. Inter-assay variability was assessed across 5 different platforms (n=47 patient specimens). ResultsIntra-day and inter-day CVs were <10% at all concentrations evaluated. The LOQ, LOD and LOB were 0.0047μIU/ml (10% CV), 0.0012μIU/ml and 0.0005μIU/ml, respectively. Variable bias was observed for the TSH3 assay when evaluated against the previous generation assay and other platforms, but overall TSH3 gave comparable results. ConclusionsThe TSH3 assay for UniCel DxI 800, is precise, highly sensitive and comparable to the previous generation assay. The assay is acceptable for clinical testing.

Commutability of control materials for external quality assessment of serum apolipoprotein A-I measurement.

The aim of the current study was to evaluate the commutability of commercial control materials and human serum pools and to investigate the suitability of the materials for the external quality assessment (EQA) of serum apolipoprotein A-I (apo A-I) measurement. The Clinical and Laboratory Standards Institute (CLSI) EP14-A3 protocol was used for the commutability study. Apo A-I concentrations in two levels of commercial control materials used in EQA program, two fresh-frozen human serum pools (FSPs) and two frozen human serum pools prepared from residual clinical specimens (RSPs) were measured along with 50 individual samples using nine commercial assays. Measurement results of the 50 individual samples obtained with different assays were pairwise analyzed by Deming regression, and 95% prediction intervals (PIs) were calculated. The commutability of the processed materials was evaluated by comparing the measurement results of the materials with the limits of the PIs. The FSP-1 was commutable for all the 36 assay pairs, and FSP-2 was commutable for 30 pairs; RSP-1 and RSP-2 showed commutability for 27/36 and 22/36 assay pairs, respectively, whereas the two EQA materials were commutable only for 4/36 and 5/36 assay pairs, respectively. Non-commutability of the tested EQA materials has been observed among current apo A-I assays. EQA programs need either to take into account the commutability-related biases in the interpretation of the EQA results or to use more commutable materials. Frozen human serum pools were commutable for most of the assays.

Analytic and quality control validation and assessment of field performance of a point‐of‐care chemistry analyzer for use in the White rhinoceros

A chemistry point-of-care analyzer would be useful for evaluating injured wildlife, particularly White rhinoceros (Ceratotherium simum) that survive poaching attempts. The IDEXX VetTest could be suitable, but species-specific validation, development of a statistical quality control (QC) strategy, and evaluation under field conditions are necessary. The objectives were to (1) validate the VetTest for the White rhinoceros, (2) perform QC validation on the VetTest and generate a statistical QC strategy, and (3) apply this QC strategy to monitor performance under typical field conditions. Differences between White rhinoceros heparin plasma and serum, short-term imprecision, and reportable range using rhinoceros plasma and long-term imprecision using commercial quality control material (QCM) were assessed against prescribed total allowable error (TEa ) for up to 15 analytes. Quality control validation was performed using data from the long-term imprecision study and TEa . A QC strategy using QCM was developed and used to monitor performance under field conditions. Imprecision was acceptable for all analytes except for ALP, ALT, and AST at low activities. The reportable range for AST and LDH differed from the manufacturer's specifications. Eleven analytes were suitable for statistical QC using the 13s rule, 3 using the 2s rule; ALP was not suitable. In the field, observed error was < TEa for all 15 analytes and the sigma metric was > 3.0 for 12 analytes. The VetTest is suitable for use in the White rhinoceros. Statistical QC is possible for most analytes and useful for evaluation of field performance.

Analytical verification and quality assessment of the Tosoh HLC-723GX HbA1c analyzer

ObjectivesIon-exchange high-performance liquid chromatography (IE-HPLC) has long been used as a reproducible and versatile analytical tool for HbA1c measurement.In this study, we performed analytical verification and quality assessment of the recently introduced small IE-HPLC Tosoh HLC-723GX HbA1c analyzer, and a comparison of results to immunoassay (IA) and capillary electrophoresis (CE). Design and methodsThe total imprecision of Tosoh HLC-723GX was verified according to CLSI EP15-A2 protocol using commercial control materials (C-QC) and pooled human whole blood samples (HWB). The Sigma metric was used for the evaluation of quality targets. HbA1c results were compared to automated CE (MiniCap Flex Piercing, Sebia, France) and IA (Tina-quant HbA1c Gen 2, Cobas Integra 400+, Roche Diagnostics, USA) procedures. ResultsThe total imprecision of Tosoh HLC-723GX-HbA1c for IFCC(mmol/mol) and NGSP(%) units was: 1.91/1.25% (HbA1c=31mmol/mol/5.0%) and 0.51/0.63% (HbA1c=84mmol/mol/9.8%) for C-QC, and 0.39/0.2% (HbA1c=47mmol/mol/6.5%) and 0.77/0.46% (HbA1c=94mmol/mol/10.8%) in HWB samples, respectively. Bland-Altman analysis did not reveal any deviation of the results between Tosoh HLC-723GX and CE: mean difference 0.0% (95%CI: −0.02927 to 0.02653%), while the mean HbA1c difference against IA was −0.07% (95%CI: −0.1039 to −0.02765). At the selected HbA1c clinical decision level (48mmol/mol/6,5%), six sigma analysis gave σ value of 3.91, within a desirable classification of performance. ConclusionThe analytical performance of the Tosoh HLC-723GX complies with the rigorous quality criteria for clinical use of HbA1c, with the results comparable to the CE procedure. Tosoh HLC-723GX provides a plausible analytical choice for reliable HbA1c measurement in low-volume laboratories.

Commutability and interchangeability of commercial quality control materials with feline plasma for common biochemical analytes.

Species-specific plasma or serum pools are considered the ideal standard material for quality control materials (QCM) instead of commercially available human QCM. However, using plasma or serum pools is limited by volume restrictions, degradation over time, and a narrow range of analyte concentrations. Concentrations of QCM analytes should be consistent or commutable with those from species-specific plasma/serum samples, and the precision from plasma pools should be comparable or interchangeable with commercial human QCM. The aims of this study were to determine the commutability and interchangeability of 2 levels of commercial QCM (MAS chemTRAK-H [CT]) with feline plasma pools (PP) from normal and renal disease cats measured using a commercial laboratory analyzer and a veterinary in-house analyzer. Agreement between the 2 analyzers was assessed for 16 analytes by correlation and Passing-Bablok regression analyses of feline plasma samples. The difference between each CT data point and the regression line (residuals) was determined and standardized, and CT were considered 'commutable' with PP if the standardized residual was within a range of -3 to 3. Coefficients of variation (CVs) for CT and PP for 16 analytes on 2 analyzers were compared by bootstrap analysis to determine interchangeability. Most CT analytes were within the range of patient plasma sample analytes, thus commutable. Only 2 analytes had equivalent precision for both levels of CT and both levels of PP, and 5 additional analytes had similar precision for at least one level of CT compared to at least one level of PP. The QCM assessed is commutable to feline PP within the tested ranges for 2 particular analyzers. Commutability does not grant interchangeability.

Quality assurance of clinical biochemistry testing: a mualti-center study based reference interval for clinical chemistry tests in the Chinese population

Objective To verify and monitor the performance of accuracy, precision and comparability of 26 clinical biochemical analytes (29 methods) in the six centers involved in multi-centers reference intervals research, and to ensure the reliability of theirmeasurement results. Methods During the period of the systems evaluating, two levels of commercial quality control materials and fresh frozen human serum reference materials were applied to verify the performance of inter-laboratory precision and accuracy of analysis systems. During the period of samples testing, the commercial quality control materials were measured whenever samples were analysed, the fresh frozen serum reference materials were measured once a month. The coefficient of variations (CVs), bias and total errors were calculated to assess the precision, accuracy and comparability. Results Verification of precision and accuracy: (1) the ranges of CVs of 29 methods in the six laboratory laboratories were 0.4%-6.0%, the CVs of all 29 methods met the criterion .(2) The overall average bias of the analysis systems of 21 analytes (24 methods) ranged from -5.15% (ALT) to 4.46% (Ur). Among 24 methods the overall average bias of TP, Glu-GOD, Ur, Cl, Ca exceeded the acceptable range. The quality assessment during the period of samples testing: (1) The overall average bias ranged from -1.95%(Ca) to 2.92%(Ur), median 1.26%, they all met the requirements of relevant standards.(2)When commercial control materials were tested, the requirements of CVs were fulfilled for most methods in the six laboratories, and the CVs of TP, Alb, Cl, Ca exceeded the acceptable range.The overall average TE of all methods met the quality specification for the C-N controls material. For the C-P control material, only the overall average TE of TP (5.05%) exceeded thearceptable range while the other methods met the requirement in criterion. Conclusions The performance of precision and accuracy of the analysis systems used in the six laboratories passed the verification. During the period of sample testing, the performance of precision and accuracy of the most methods in the 6 laboratories met the requirements of quality specifications, and the overall performance was good. Because of the limitation of current technology the performance of some methods didn't fulfill the requirement of specifications, and need to be improved.(Chin J Lab Med, 2015, 38: 301-305) Key words: Reference values; Quality assurance, health care; Clinical chemistry tests; Laboratory proficiency testing

HORMONAL IMMUNOASSAYS

Objectives: several improvements have been made in the design of immunoassayssuch as method of antibody production, labeling, automation and detection technology. The aim ofthe present study was to compare the accuracy and precision of enzyme linked immunofloriscenceassay (ELFA) and electrochemiluminescence assay (ECL), with Elisa for determination of serum TSHlevels. Period: Feb 2014 to Nov 2014. Setting: College of postgraduate studies, University of Al-Neelain, Khartoum, Sudan. Material and Methods: Three commercial control materials low, normaland high levels of TSH, were used for imprecision studies of immunofloriscence assay (ELFA) andelectrochemiluminescence assay (ECL) methods and 120 patients samples including low (20%),normal (50%), and high (30%) TSH levels, were measured by the two methods, and used for methodscomparison. In addition to six assigned prepared pool serum used for linearity evaluation of the twomethods. Results: Inter- and intra-assay CV% for ECL and ELFA was significantly low compared withthe required by the manufacture. (Intraassay CV% for ECL was 2.9%, 2.74%, and 2.55% for low,normal, and high respectively of TSH levels of the control sera. Intraassay CV% for ELFA was 3.95%,3.75%, and 5.73% for low, normal, and high respectively of TSH levels of the control sera. InterassayCV% for ECL was 3.0%, 2.75%, and 2.81% for low, normal, and high respectively of TSH levels ofthe control sera. Intraassay CV% for ELFA was 4.26%, 4.0% , and 5.75% for low, normal , and highrespectively of TSH levels of the control sera. Although the mean TSH levels of the three levels of thecontrol sera measured by ECL &amp; ELFA methods, is significantly difference from assigned TSH meanvalues( low 0.488+/-0.078,normal 6.016+/- 0.952,high 33.651+/-5.39) , but the measured values iswithin the mean range of the assigned means values. ECL; low (0.611 +/- 0.018. p ≤ 0.001), normal(6.6785 +/- 0.183. p ≤ 0.00), high (35.0485 +/- 0.894. p ≤ 0.02). ELFA low (0.50545 +/- 0.020. p ≤0.00) , normal (6.5395 +/- 0.244. p ≤ 0.00), high (31.0350 +/- 1.779. p ≤0.001).The mean TSH levelsof the 120 patients samples measured by ECL &amp; ELFA , is significantly difference , for ECL (15.74+/-1.181 . p ≤ 0.00) when compared with the mean TSH value (14.56 +/- 1.65) of the patients samples.For ELFA method also there is significant difference (13.76 +/- 1.59 , p ≤ 0.00) when comparedwith mean of the assigned TSH values(14.56 +/- 1.65) of the patients samples, but within the targetvalues of the means .The study showed strong relationship between the two TSH levels measuredby ECL( mean 15.74 mIU/L, slope 0.67 , correlation coefficients 0.991, p ≤ 0.00) and by ELFA (mean 13.76 mIU/L, slope 0.54, correlation coefficients 0.995, p ≤ 0.00) with the assigned values(14.56 ) of 120 patients sample .The results illustrates no significant difference of TSH mean level insix prepared pool samples measured by ECL(22.63 mIU/l +/- 1.12 , p ≤ 0.1) and ELFA(19.87mIU/l+/- 1.15 , p ≤ 0.11) when compared with the TSH assigned values(22.54 mIU/l +/-0.96), and withstrong correlation between the two TSH levels measured by ECL(22.63 mIU/l, slope 0.79, correlationcoefficients 0.999, p ≤ 0.00) and ELFA ( mean 19.87mIU, slope 0.68, correlation coefficients 0.985,p ≤ 0.00), with the assigned TSH values (22.54 mIU/l +/-0.96).of the six prepared pool samples.Conclusion: Considerable significant precision and accuracy was manifested by both ECL and ELFAmethods in estimation of TSH levels, but ECL is more precise than ELFA especially in the lower TSHconcentration.

Performance characteristics of the Beckman Coulter total βhCG (5th IS) assay

BackgroundBeckman Coulter recently released the first commercially available hCG reagent calibrated against the 5th International Standard (IS) for hCG (total βhCG (5th IS)). We performed a comprehensive analytical validation of this reagent. MethodsPrecision experiments were completed using 3 concentrations of commercial quality control material. Linearity, sample stability, and analytical sensitivity were evaluated using pools of human serum. Reportable range was assessed by comparing manual dilutions to those performed by the instrument. Male and female reference intervals were established using residual serum specimens submitted for routine testing. Inter-lot variability of hCG assay reagent was assessed by analyzing serum specimens with detectable hCG using 2 different reagent lots. Inter-assay variability was established using 203 serum specimens analyzed for hCG on 6 different reagent platforms. ResultsInter-day precision showed a CV of <6.0% for all concentrations of QC material. LOB, LOD, and LOQ were determined to be 0.3, 0.4, and 0.6U/l, respectively. The Access (5th IS) reagent has an average positive bias of approximately 20% when compared to most platforms and the previous generation Beckman hCG assay. Results were consistent between lots. Female reference intervals varied by age: <1.0U/l (<41y), <6.0U/l (41–50y), and <8.0U/l (>50y). Male reference intervals were <2.0U/l. ConclusionsThe analytical performance of the total βhCG (5th IS) was established. Care should be taken to re-baseline patients needing serial monitoring and/or notify physicians when transitioning to the total βhCG (5th IS) reagent.

Commutability of possible external quality assessment materials for cardiac troponin measurement.

BackgroundThe measurement of cardiac troponin is crucial in the diagnosis of myocardial infarction. The performance of troponin measurement is most conveniently monitored by external quality assessment (EQA) programs. The commutability of EQA samples is often unknown and the effectiveness of EQA programs is limited.MethodsCommutability of possible EQA materials was evaluated. Commercial control materials used in an EQA program, human serum pools prepared from patient samples, purified analyte preparations, swine sera from model animals and a set of patient samples were measured for cTnI with 4 assays including Abbott Architect, Beckman Access, Ortho Vitros and Siemens Centaur. The measurement results were logarithm-transformed, and the transformed data for patient samples were pairwise analyzed with Deming regression and 95% prediction intervals were calculated for each pair of assays. The commutability of the materials was evaluated by comparing the logarithmic results of the materials with the limits of the intervals. Matrix-related biases were estimated for noncommutable materials. The impact of matrix-related bias on EQA was analyzed and a possible correction for the bias was proposed.ResultsHuman serum pools were commutable for all assays; purified analyte preparations were commutable for 2 of the 6 assay pairs; commercial control materials and swine sera were all noncommutable; swine sera showed no reactivity to Vitros assay. The matrix-related biases for noncommutable materials ranged from −83% to 944%. Matrix-related biases of the EQA materials caused major abnormal between-assay variations in the EQA program and correction of the biases normalized the variations.ConclusionCommutability of materials has major impact on the effectiveness of EQA programs for cTnI measurement. Human serum pools prepared from patient samples are commutable and other materials are mostly noncommutable. EQA programs should include at least one human serum pool to allow proper interpretation of EQA results.

The instability of commercial control materials in quality control of mean corpuscular volume

BackgroundMean corpuscular volume (MCV) of stabilized whole blood used for quality control (QC) of hematology analyzers exhibits a tendency to increase during storage. The aim of this study is to evaluate the extent of biases over time with 3 most widely used control materials and to map out a strategy to overcome the data shift of MCV on daily QC practice. MethodsQC results of TESTPoint tested by ADVIA 2120i, e-CHEK tested by XE 2100, and 6C Cell Control tested by DxH 800 were analyzed. ResultsMCV of all control materials showed a tendency to increase over time. By the fifth week, most of the materials showed biases larger than one standard deviation, with some exceeding a bias of four standard deviations. ConclusionsLaboratories should apply appropriate QC strategies in MCV tests by considering their individual quality and efficiency requirements.