1,721,005 research outputs found
Riferibilità metrologica e validità della determinazione della creatinina come indice di funzionalità renale
No full textField evaluation of Spaplus system for the determination of free light chains (FLC)in serum
No full textBackground: Measurements of serum immunoglobulin k and λ FLC and FLC ratio calculation are recommended for the evaluation of plasma cell disorders. Several practical issues for
the analytical measurement of FLC have, however, been identified. Searching for a solution able to fulfil the performance goals for the effective use of FLC in clinical setting, we evaluated the suitability of SPAplus analyzer using Freelite reagents (both from The Binding Site) for FLC determination.
Particularly, we compared the system performance with allowable goals for bias, imprecision (CV) and total error (TE) derived from biologic variation of FLC.
Methods: We evaluated the performance of SPAplus FLC using data collected during a six-month time period of routine use,employing two different reagent lots. The two-level (N and H)
liquid SPAplus control material was used for bias estimate by comparing the obtained long-term experimental means (n=34, both levels) with the corresponding assigned values. The
protocol for CV evaluation employed the liquid-frozen Bio-Rad Liquichek Unassayed Chemistry Control, measured in each performed run for a total of 29 runs. Inaccuracy was checked by results from three UK NEQAS exercises (system-specific (SPAplus) consensus value as reference). Goals (desirable/minimum quality levels) for bias, CV and TE were
±4.1%/6.1%, <4.0%/6.0% and ±10.7%/16.1% for κFLC and ±7.1%/10.6%, <3.5%/5.3% and ±12.9%/19.3% for λFLC,respectively. In addition, CV and TE for FLC ratio should be <2.3%/3.4% and ±7.7%/11.6%.
Results: Average cumulative bias was -6.0% (control N) and - 6.2% (control H) for κFLC, and 4.3% (N) and 6.1% (H) for
λFLC, respectively. Overall CV resulted in 10.8% for κFLC
(mean 11.9 mg/L), 7.3% for λFLC (mean 13.6mg/L) and 8.8%
for FLC ratio (mean 0.9). On EQAS evaluation all λFLC and
two out of 3 results for κFLC were within the minimum
allowable TE, while the FLC ratio achieved the minimum goal
only in one exercise.
Conclusions: Considering our previous experience with other
analytical systems, the SPAplus solution undoubtedly
represents a significant step forward. A further improvement in
measurement imprecision (priority) and method alignment is
probably needed to fulfil the stringent analytical goals derived
from biologic variation
Valutazione delle prestazioni del sistema analitico SPAPluS per la misura della catene leggere libere del siero
No full textMeasurements of serum immunoglobulin κ and λ free light chains (FLC) and FLC ratio calculation are recommended for the evaluation of plasma cell disorders. In this study we evaluated the performance of SPAPLUS analyzer using FreeliteTM reagents (both from The Binding Site) for FLC determination. Particularly, we compared the system performance with allowable goals for bias, imprecision and total error derived from biological variation of FLC. We evaluated the SPAPLUS FLC using data collected during a 10-month period of routine use, employing three different reagent lots. The two-level (N and H) SPAPLUS control material was used for bias estimate by comparing the obtained long-term experimental means (n=54, both levels) to the corresponding manufacturer's assigned values. The protocol for CV evaluation employed the liquid-frozen Bio-Rad Liquichek unassayed chemistry control, measured in each performed run (n=48). Inaccuracy was checked by results from five UK-NEQAS exercises [system-specific (SPAPLUS) consensus value as reference]. Average cumulative bias was -1.5% (control N) and -1.4% (control H) for κ FLC, and +6.6% (N) and +6.3% (H) for λ FLC, respectively. Overall CV at physiological concentrations resulted in 10.6% for κ FLC, 8.0% for λ FLC and 9.9% for FLC ratio. On EQAS evaluation, all λ FLC, four κ FLC and three FLC ratio results were within the minimum allowable total error. Considering our previous experience with other analytical systems, the SPAPLUS solution undoubtedly represents a significant step forward. However, a further improvement in measurement imprecision is probably needed to fulfill the stringent analytical goals derived from FLC biological variation
Confronto tra due sistemi per elettroforesi capillare e in gel d’agarosio per la ricerca e caratterizzazione di componenti monoclonali nel siero
No full textComparison of capillary and agarose gel electrophoresis for the identification and characterization of monoclonal immunoglobulins. The aim of this study was to compare the performance of two systems for agarose gel (AGE) and capillary (CZE) serum protein electrophoresis (SAS3/4/5 Alfa Wassermann and Paragon CZE 2000
Beckman Coulter) for the detection and characterization of monoclonal immunoglobulins (M proteins). Two
independent persons reviewed 960 consecutively ordered serum protein electrophoresis patterns, 79 (8.2%) of which
showed one or more M proteins at immunofixation. For M protein detection, we found similar sensitivities for AGE and CZE (89.9% vs. 94.9%, P = 0.368), with AGE showing high specificity than CZE (99.3% vs. 96.3%, P <0.0001). With regards to M protein characterization, performed on a series of 41 consecutive samples (25 of which positive
for M proteins), agreement between methods was 97.6%. A good correlation (r2 = 0.947) was found when the two methods were compared for M protein quantitation (n = 180), even if a more pronounced bias was noted with M
protein concentrations >25 g/L. In agreement with previously published studies, we conclude that both AGE and CZE techniques can be used in clinical laboratories for M protein detection and characterization, even if the detection specificity of AGE as a screening test is higher
Stima dell’incertezza della misura della concentrazione di attività catalitica dell’alanina amminotransferasi (ALT) nel siero mediante il metodo di riferimento IFCC
No full textCalculation of uncertainty of measurement of the catalytic activity concentration of alanine amminotransferase (ALT) in serum by the IFCC reference procedure. The goal of standardization of measurements in Laboratory Medicine is to achieve comparable results in human samples, independent of the
laboratory and/or the method used. This can be achieved by the adoption of the “reference system” approach, based on the concept of metrological traceability and a hierarchy of measurement procedures. The reference system requires reference procedures, reference materials and reference laboratories, which are able to produce results within defined limits of uncertainty. The model used by the reference laboratories to estimate the measurement uncertainty is the “bottom-up” approach proposed by the Guide to the expression of uncertainty of measurement (GUM). The purpose
of this study was to estimate the uncertainty associated with the measurement of the catalytic activity concentration of
the enzyme ALT by the IFCC reference procedure using this approach. All the sources of uncertainty were identified
and their contribution to the final expanded uncertainty was calculated using literature data or ad hoc experiments. We obtained an expanded uncertainty of 2.36%, comparable to that already calculated and published by other accredited reference laboratories. The uncertainty budget was built showing that concentrations and lot of reagents and
measurement repeatability are the main components of the expanded uncertainty of the ALT measurements
Determinazione dell’epcidina : ma cosa stiamo misurando? = Determination of hepcidin : but what we are measuring?
No full textImprecisione di alcuni metodi di misura dell’albumina derivata dai dati di un Controllo di Qualità Interno
No full textComparison of capillary and agarose gel electrophoresis for the identification and characterization of monoclonal immunoglobulins
No full textThe objective of this study was to compare gel-and capillary-based serum protein electrophoresis methods to identify and characterize monoclonal immunoglobulins (M proteins). Five reviewers interpreted 149 consecutively ordered serum specimens following agarose gel electrophoresis (AGE), capillary electrophoresis (CE), immunofixation electrophoresis (IFE), and subtraction immunotyping (IT). As a screening test for detecting M proteins, AGE and CE displayed similar sensitivity (91% and 92%, respectively). CE was less specific (74%) than AGE (81%). An analysis of interinterpreter agreement revealed that interpretations were more consistent using gel-based methods than capillary-based methods, with 80% of the gel interpretations being in complete (5/5) agreement compared with 67% of the capillary interpretations. After implementing the capillary-based methods, the number of tests per reportable result increased (from 1.58 to 1.73). CE is an analytically suitable alternative to AGE, but laboratories implementing it will need to continue IFE testing to characterize all M proteins detected by CE
Measurement uncertainty : friend or foe?
No full textThe definition and enforcement of a reference measurement system, based on the implementation of metrological traceability of patients' results to higher order reference methods and materials, together with a clinically acceptable level of measurement uncertainty, are fundamental requirements to produce accurate and equivalent laboratory results. The uncertainty associated with each step of the traceability chain should be governed to obtain a final combined uncertainty on clinical samples fulfilling the requested performance specifications.
It is important that end-users (i.e., clinical laboratory) may know and verify how in vitro diagnostics (IVD) manufacturers have implemented the traceability of their calibrators and estimated the corresponding uncertainty. However, full information about traceability and combined uncertainty of calibrators is currently very difficult to obtain. Laboratory professionals should investigate the need to reduce the uncertainty of the higher order metrological references and/or to increase the precision of commercial measuring systems.
Accordingly, the measurement uncertainty should not be considered a parameter to be calculated by clinical laboratories just to fulfil the accreditation standards, but it must become a key quality indicator to describe both the performance of an IVD measuring system and the laboratory itself
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