Biochemia Medica最新文献

Introduction: Leukolysis-related pseudohyperkalemia due to preanalytical procedures may lead to erroneous (or absence of) treatment based on an invalid lab test result. We aimed to obtain a leukocyte threshold above which leukolysis-related pseudohyperkalemia becomes clinical relevant. Secondly, temporal dynamics of treatment-induced leukocyte decrease were studied to allow tailored implementation of laboratory information system (LIS) decision rules based on the leukocyte threshold to avoid leukolysis-related pseudohyperkalemia.

Materials and methods: Potassium results of AU5811 routine chemistry (Beckman Coulter, Brea, California, USA) and iStat point of care (POC) (Abbott Diagnostics, Chicago, Illinois, USA) analysers were compared, the latter method being insensitive to leukolysis caused by pre-analytical procedures. Potassium results were combined with leukocyte counts obtained using a Cell-Dyn Sapphire haematology analyser (Abbott Diagnostics, Santa Clara, California, USA), resulting in 132 unique data triplets. Regression analysis was performed to establish a leukocyte threshold. The Reference Change Value (√2 x Z x √(CV_a ² + CV_i ²)) was used to calculate maximum allowable difference between routine analyser and POC potassium results (delta_max + 0.58 mmol/L). Temporal analysis on the treatment-induced leukocyte decrease was performed by plotting leukocyte counts in time for all patients above the threshold leukocyte count (N = 41).

Results: Established leukocyte threshold was 63 x10⁹/L. Temporal analysis showed leukocyte counts below the threshold within 8 days of treatment for all patients.

Conclusions: Based on performed analyses we were able to implement LIS decision rules to reduce pseudohyperkalemia due to preanalytical procedures. This implementation can contribute to a reduction in erroneous (or absence of) treatments in the clinic.

Introduction: Interpretation of laboratory test results is a complex post-analytical activity that requires not only understanding of the clinical significance of laboratory results but also the analytical phase of laboratory work. The aims of this study were to determine: 1) the general opinion of Croatian medical biochemistry laboratories (MBLs) about the importance of interpretative comments on laboratory test reports, and 2) to find out whether harmonization of interpretative comments is needed.

Materials and methods: This retrospective study was designed as a survey by the Working Group for Post-analytics as part of national External Quality Assessment (EQA) program. All 195 MBLs participating in the national EQA scheme, were invited to participate in the survey. Results are reported as percentages of the total number of survey participants.

Results: Out of 195 MBLs, 162 participated in the survey (83%). Among them 59% MBLs implemented test result comments in routine according to national recommendations. The majority of laboratories (92%) state that interpretative comments added value to the laboratory reports, and a substantial part (72%) does not have feedback from physicians on their significance. Although physicians and patients ask for expert opinion, participants stated that the lack of interest of physicians (64%) as well as the inability to access patient's medical record (62%) affects the quality of expert opinion.

Conclusion: Although most participants state that they use interpretative comments and provide expert opinions regarding test results, results of the present study indicate that harmonization for interpretative comments is needed.

Introduction: The interest in quality management tools/methodologies is gradually increasing to ensure quality and accurate results in line with international standards in clinical laboratories. Six Sigma stands apart from other methodologies with its total quality management system approach. However, the lack of standardization in tolerance limits restricts the advantages for the process. Our study aimed both to evaluate the applicability of analytical quality goals with Roche Cobas c 702 analyser and to determine achievable goals specific to the analyser used.

Materials and methods: The study examined under two main headings as Sigma_laboratory and Sigma_analyser. Sigma_laboratory was calculated using internal and external quality control data by using Roche Cobas c 702 analyser for 21 routine biochemistry parameters and, Sigma_analyser calculation was based on the manufacturer data presented in the package inserts of the reagents used in our laboratory during the study. Sigma values were calculated with the six sigma formula.

Results: Considering the total number of targets achieved, Sigma_analyser performed best by meeting all CLIA goals, while Sigma_laboratory showed the lowest performance relative to biological variation (BV) desirable goals.

Conclusions: The balance between the applicability and analytical assurance of "goal-setting models" should be well established. Even if the package insert data provided by the manufacturer were used in our study, it was observed that almost a quarter of the evaluated analytes failed to achieve even "acceptable" level performance according to BV-based goals. Therefore, "state-of-the-art" goals for the Six Sigma methodology are considered to be more reasonable, achievable, and compatible with today's technologies.

Introduction: This study reevaluated von Willebrand disease (vWD) diagnosis in a Croatian paediatric cohort by combining bleeding scores (BS), phenotypic laboratory testing, and next-generation sequencing (NGS).

Materials and methods: A total of 25 children (11 males and 14 females, median age 10 years, from 2 to 17) previously diagnosed with vWD were included. BS were calculated using an online bleeding assessment tool. Phenotypic laboratory analyses included platelet count, platelet function analyser closure times, prothrombin time, activated partial thromboplastin time, von Willebrand factor antigen (vWF:Ag), vWF gain-of-function mutant glycoprotein Ib binding activity (vWF:GPIbM), vWF collagen binding activity (vWF:CBA), factor VIII activity (FVIII:C) and multimeric analysis. Next-generation sequencing covered regions of both vWF and FVIII genes and was performed on MiSeq (Illumina, San Diego, USA).

Results: Disease-associated variants identified in 15 patients comprised 11 distinct heterozygous vWF gene variants in 13 patients and one novel FVIII gene variant (p.Glu2085Lys) in two male siblings. Four vWF variants were novel (p.Gln499Pro, p.Asp1277Tyr, p.Asp1277His, p.Lys1491Glu). Three patients without distinctive variants had vWF:GPIbM between 30 and 50%. Patients with identified vWF gene variants had statistically significant lower values of vWF:GPIbM (P = 0.002), vWF:Ag (P = 0.007), vWF:CBA (P < 0.001) and FVIII:C (P = 0.002), compared to those without. Correlations between BS and phenotypic laboratory test results were not statistically significant for either of the tests.

Conclusion: The applied diagnostic approach confirmed the diagnosis of vWD in 13 patients and mild haemophilia A in two. Limited utility of BS in the paediatric population was evidenced.

Introduction: The aims of study were to assess: 1) performance specifications of Atellica 1500, 2) comparability of Atellica 1500 and Iris, 3) the accuracy of both analysers in their ability to detect bacteria.

Materials and methods: Carryover, linearity, precision, reproducibility, and limit of blank (LoB) verification were evaluated for erythrocyte and leukocyte counts. ICSH 2014 protocol was used for estimation of carryover, CLSI EP15-A3 for precision, and CLSI EP17 for LoB verification. Comparison for quantitative parameters was evaluated by Bland-Altman plot and Passing-Bablok regression. Qualitative parameters were evaluated by Weighted kappa analysis. Sixty-five urine samples were randomly selected and sent for urine culture which was used as reference method to determine the accuracy of bacteria detection by analysers.

Results: Analytical specifications of Atellica 1500 were successfully verified. Total of 393 samples were used for qualitative comparison, while 269 for sediment urinalysis. Bland-Altman analysis showed statistically significant proportional bias for erythrocytes and leukocytes. Passing-Bablok analysis for leukocytes pointed to significant constant and minor proportional difference, while it was not performed for erythrocytes due to significant data deviation from linearity. Kappa analysis resulted in the strongest agreements for pH, ketones, glucose concentrations and leukocytes, while the poorest agreement for bacteria. The sensitivity and specificity of bacteria detection were: 91 (59-100)% and 76 (66-87)% for Atellica 1500 and 46 (17-77)% and 96 (87-100)% for Iris.

Conclusion: There are large differences between Atellica 1500 and Iris analysers, due to which they are not comparable and can not be used interchangeably. While there was no difference in specificity of bacteria detection, Iris analyser had greater sensitivity.

During a dual-center study on obese and normal weight children and adolescents, focusing on glucose metabolism, we observed a marked difference in glucose results (N = 16,840) between the two sites, Salzburg, Austria and Uppsala, Sweden (P < 0.001). After excluding differences in patient characteristics between the two populations as cause of this finding, we investigated other preanalytic influences. Finally, only the tubes used for blood collection at the two sites were left to evaluate. While the Vacuette FC-Mix tube (Greiner Bio-One, Kremsmünster, Austria) was used in Uppsala, in Salzburg blood collections were performed with a lithium heparin tube (LH-Monovette, Sarstedt, Germany). To prove our hypothesis, we collected two blood samples in either of these tubes from 51 children (Salzburg N = 27, Uppsala N = 24) and compared the measured glucose results. Indeed, we found the suspected bias and calculated a correction formula, which significantly diminished the differences of glucose results between the two sites (P = 0.023). Our finding is in line with those of other studies and although this issue should be widely known, we feel that it is widely neglected, especially when comparing glucose concentrations across Europe, using large databases without any information on preanalytic sample handling.

Creatinine and estimated glomerular filtration rate (eGFR) are first-line laboratory parameters in the diagnosis of various renal diseases. In recent decades, cystatin C (cysC) has furthered the laboratory repertoire regarding renal status assessment and has been implemented in many clinical guidelines. Accordingly, with the establishment of cysC as a renal routine biomarker, further opportunities for assessing eGFR have been attained. Nevertheless, various limitations are still associated with cysC and creatinine analysis. Preanalytical errors could cause false results in both biomarkers. In our case, we were confronted with implausibly elevated creatinine levels due to preanalytical errors.

Introduction: Moving average (MA) is one possible way to use patient results for analytical quality control in medical laboratories. The aims of this study were to: (1) implement previously optimized MA procedures for 10 clinical chemistry analytes into the laboratory information system (LIS); (2) monitor their performance as a real-time quality control tool, and (3) define an algorithm for MA alarm management in a small-volume laboratory to suit the specific laboratory.

Materials and methods: Moving average alarms were monitored and analysed over a period of 6 months on all patient results (total of 73,059) obtained for 10 clinical chemistry parameters. The optimal MA procedures were selected previously using an already described technique called the bias detection simulation method, considering the ability of bias detection the size of total allowable error as the key parameter for optimization.

Results: During 6 months, 17 MA alarms were registered, which is 0.023% of the total number of generated MA values. In 65% of cases, their cause was of pre-analytical origin, in 12% of analytical origin, and in 23% the cause was not found. The highest alarm rate was determined on sodium (0.10%), and the lowest on calcium and chloride.

Conclusions: This paper showed that even in a small-volume laboratory, previously optimized MA procedures could be successfully implemented in the LIS and used for continuous quality control. Review of patient results, re-analysis of samples from the stable period, analysis of internal quality control samples and assessment of the analyser malfunctions and maintenance log have been proposed for the algorithm for managing MA alarms.

Introduction: In previous research projects and clinical settings, alcohol analysis in oral fluid (saliva) has been used as an alternative to breath or blood alcohol testing. In this study we examined whether it is possible to obtain clinically relevant data regarding alcohol consumption in individuals who recently consumed alcohol by analysing oral fluid samples when the recommended rinsing of the mouth is impossible before sample collection.

Materials and methods: We conducted a study of 89 nightclub patrons in Norway. Before collecting oral fluid samples and performing breath alcohol testing, participants were required to drink a glass of water to remove residual alcohol from the mouth. Oral fluid samples were collected with the Quantisal oral fluid collection device and analysed using an enzymatic method for alcohol. The alcohol concentration in the neat (undiluted) oral fluid was then calculated. Breath alcohol testing was performed using Lion Alcolmeter 500 instruments.

Results: No false-negative or false-positive results for alcohol were detected in the oral fluid when compared with those in the breath. The Intraclass Correlation Coefficient of 0.40 indicated a poor correlation between alcohol concentrations in the two sample types.

Conclusions: The procedure for collecting oral fluid was suitable for the qualitative determination of alcohol intake but not for quantitative assessment. We recommend that oral fluid samples should not be used for estimating blood or breath alcohol concentrations in people who have recently consumed alcohol or non-alcoholic beverages, as recommended in the instructions for use.