Maria Stella Graziani

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Martina Zaninotto

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Ferruccio Ceriotti
Davide Giavarina
Bruna Lo Sasso
Giampaolo Merlini
Martina Montagnana
Andrea Mosca
Paola Pezzati
Rossella Tomaiuolo
Matteo Vidali

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Marcello Ciaccio Italy
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Giuseppe Lippi Italy
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BC: Articoli scritti da I. Infusino

Determinazione della concentrazione dell’inibitore C1 esterasi nel siero: un invito alla standardizzazione
Determination of C1-esterase inhibitor concentration in serum: a call for standardization
Biochimica Clinica ; 42(1) 79-81
Lettere all'Editore - Letters to the Editor
Valutazione del sistema Optilite™ per la misura delle catene leggere libere delle immunoglobuline nel siero
Evaluation of the Optilite™ system for the determination of immunoglobulin free light chains in serum (sFLC)
<p>The measurement of sFLC<span style="font-size:14px"><span style="color:rgb(35, 31, 32); font-family:symbol">k</span></span> and l and <span style="color:rgb(35, 31, 32); font-family:symbol; font-size:14px">k</span>/<span style="color:#231F20; font-family:symbol; font-size:12.0pt">l</span> ratio calculation is recommended for evaluation and management of plasma cell disorders. However, some analytical issues persist in their measurements, among which a too large long-term imprecision seems to be the main challenge. We evaluated the new Optilite system (The Binding Site) for sFLC determination by comparing its performance with specifications for bias, imprecision (as CV) and total error derived from biological variation of sFLC. We collected data during one year of routine use by employing three reagent lots. The system alignment was checked using the two-level (L and H) Optilite control material by comparing the obtained long-term experimental mean (n=233, both levels) with the manufacturer&rsquo;s assigned values. The protocol for CV evaluation employed the liquid-frozen BioRad Liquichek Control and a frozen serum pool tested for 125 and 79 runs, respectively. Inaccuracy was evaluated by results of four UK-NEQAS exercises [system-specific (Optilite) consensus value as reference]. Average cumulative bias [1.1% (L) and -2.0% (H) for sFLC<span style="color:rgb(35, 31, 32); font-family:symbol; font-size:14px">k</span>; 5.4% (L) and 0.1% (H) for sFLC<span style="color:rgb(35, 31, 32); font-family:symbol; font-size:16px">l</span>, respectively] fulfilled the desirable goals. CVs for sFLC<span style="color:rgb(35, 31, 32); font-family:symbol; font-size:14px">k</span> (7.1% for Liquichek and 6.6% for the pool, respectively), sFLC<span style="color:rgb(35, 31, 32); font-family:symbol; font-size:16px">l</span> (7.8% for both Liquichek and the pool) and <span style="color:rgb(35, 31, 32); font-family:symbol; font-size:14px">k</span>/<span style="color:rgb(35, 31, 32); font-family:symbol; font-size:12pt">l&nbsp;</span>ratio (8.9% for Liquichek and 10.2% for the pool, respectively) failed however to reach minimum quality goals. In EQAS evaluation, all sFLC <span style="color:rgb(35, 31, 32); font-family:symbol; font-size:14px">k</span> and <span style="color:rgb(35, 31, 32); font-family:symbol; font-size:16px">l</span> and 3 out of 4 <span style="color:rgb(35, 31, 32); font-family:symbol; font-size:14px">k</span>/<span style="color:rgb(35, 31, 32); font-family:symbol; font-size:12pt">l</span> ratio results were within the allowable total error. In our experience, the Optilite system shows a good method alignment suitable for sFLC interpretation using fixed cut-offs. However, the assay reproducibility is probably not suitable for optimal long-term monitoring of individual patients.</p>
Biochimica Clinica ; 42(1) 32-38
Contributi scientifici - Scientific papers
Valutazione dell’esattezza della misura della fosfatasi alcalina sierica in un gruppo di laboratori italiani
Evaluation of the trueness of serum alkaline phosphatase (ALP) measurement in a group of Italian laboratories
<p>The reference measurement procedure for ALP published in 2011 by the IFCC allowed to define the metrological traceability chain for the standardization of ALP measurement. This paper reports the results of an EQA experiment conducted to evaluate the level of ALP standardization among different Italian laboratories enrolled for a scientific project with the final aim to derive ALP traceable reference intervals for pediatric population. Three frozen serum pools with a target value assigned by the IFCC reference procedure were distributed to 13 centers and analyzed in triplicates for 3 different days. Only 3 laboratories averagely fulfilled the desirable goal of bias (&le;&plusmn;5.5%) at all 3 concentrations (59.9 U/L, 186.9 U/L and 401.5 U/L), but only one provided data with a dispersion always within the uncertainty of the target result. The different ability to meet the goal clearly depended on the analytical system used. Focusing on the two most used analytical platforms, the Cobas systems (Roche Diagnostics) underestimated the ALP values, while the AU systems (Beckman Coulter) overestimated them. The regression parameters between the average values obtained by laboratories and the target values indicate that it would be possible to correct the results of all analytical systems and make them unbiased by a simple recalibration approach. The analysis of the commercial calibrator package inserts of the IVD companies involved in this study showed that, with the exception of Roche still aligned to the old Tietz method published in 1983, all companies offer at least two options, sometimes (e.g., Beckman AU) both not in line with the recommended standardization approach.</p>
Biochimica Clinica ; 41(1) 064-071
Contributi scientifici - Scientific papers
Valutazione delle prestazioni del sistema analitico SPAPLUS per la misura delle catene leggere libere del siero
Evaluation of the performance of SPAPLUS system for the measurement of free light chains in serum
<p>Measurements of serum immunoglobulin <span style="font-family:symbol">k</span> and <span style="font-family:symbol">l</span> free light chains (FLC) and FLC ratio calculation are recommended&nbsp;for the evaluation of plasma cell disorders. In this study we evaluated the performance of SPAPLUS analyzer using&nbsp;Freelite<span style="font-size:x-small"><sup>TM</sup></span> reagents (both from The Binding Site) for FLC determination. Particularly, we compared the system&nbsp;performance with allowable goals for bias, imprecision and total error derived from biological variation of FLC. We&nbsp;evaluated the SPAPLUS FLC using data collected during a 10-month period of routine use, employing three different&nbsp;reagent lots. The two-level (N and H) SPAPLUS control material was used for bias estimate by comparing the obtained&nbsp;long-term experimental means (n=54, both levels) to the corresponding manufacturer&rsquo;s assigned values. The protocol&nbsp;for CV evaluation employed the liquid-frozen Bio-Rad Liquichek unassayed chemistry control, measured in each&nbsp;performed run (n=48). Inaccuracy was checked by results from five UK-NEQAS exercises [system-specific (SPAPLUS)&nbsp;consensus value as reference]. Average cumulative bias was -1.5% (control N) and -1.4% (control H) for <span style="font-family:symbol">k</span> FLC, and&nbsp;+6.6% (N) and +6.3% (H) for <span style="font-family:symbol">l</span> FLC, respectively. Overall CV at physiological concentrations resulted in 10.6% for <span style="font-family:symbol">k</span> FLC, 8.0% for <span style="font-family:symbol">l</span> FLC and 9.9% for FLC ratio. On EQAS evaluation, all <span style="font-family:symbol">l</span> FLC, four <span style="font-family:symbol">k</span> FLC and three FLC ratio results&nbsp;were within the minimum allowable total error. Considering our previous experience with other analytical systems, the&nbsp;SPAPLUS solution undoubtedly represents a significant step forward. However, a further improvement in measurement&nbsp;imprecision is probably needed to fulfill the stringent analytical goals derived from FLC biological variation.</p>
Biochimica Clinica ; 37(5) 370-375
Contributi Scientifici - Scientific Papers
Variabilità biologica delle catene leggere libere delle immunoglobuline nel siero
Biologic variation of immunoglobulin free light chains in serum
<p>The measurement of serum <span style="font-family:symbol">k</span> and <span style="font-family:symbol">l</span> free light&nbsp;chains (FLC) and <span style="font-family:symbol">k</span>/<span style="font-family:symbol">l</span> FLC ratio calculation are recommended for screening, prognostic evaluation and monitoring of&nbsp;multiple myeloma and related plasma cell disorders. Given the lack of reliable data available in literature, in this study&nbsp;we assessed biologic variability components of FLCs and FLC ratio by an accurately designed protocol. We collected&nbsp;five blood specimens from each of 21 healthy volunteers (9 men and 12 women; age range, 23-54 years) on the same&nbsp;day, every two weeks for two months. Serum specimens were stored at -80 &deg;C until analysis and analyzed in a single&nbsp;run in duplicate using a SPAPLuS immunoturbidimetric platform and Freelite reagents (The Binding Site). Data were&nbsp;analyzed by ANOVA. Serum <span style="font-family:symbol">l</span> FLC concentrations were significantly (P &lt;0.01) higher in men. The inter-individual&nbsp;variance of <span style="font-family:symbol">l</span> FLC was higher than that of <span style="font-family:symbol">k</span> FLC. Within- and between-subject CVs were 8.1% and 14.1% for <span style="font-family:symbol">k</span> FLC,&nbsp;7.0% and 27.5% for <span style="font-family:symbol">l</span> FLC, and 4.5% and 15.3% for FLC ratio. All parameters had marked individuality showing that&nbsp;the use of population-based reference intervals could be inadequate for test interpretation. The reference change&nbsp;value was between 20% and 30% depending from the assay imprecision. Desirable analytical goals for imprecision&nbsp;(CV), bias and total error were &lt;4.0%, &plusmn;4.1% and &plusmn;10.7% for <span style="font-family:symbol">k</span> FLC, &lt;3.5%, &plusmn;7.1% and &plusmn;12.9% for <span style="font-family:symbol">l</span> FLC, and&nbsp;&lt;2.3%, &plusmn;4.0% and &plusmn;7.7% for FLC ratio.</p>
Biochimica Clinica ; 37(5) 376-382
Contributi Scientifici - Scientific Papers
Determinazione dell’epcidina: ma cosa stiamo “misurando”?
Quantification of hepcidin: what are we measuring?
Biochimica Clinica ; 37(2) 135-137
Lettere all'Editore - Letters to the Editor
Accuratezza nella misura e impiego clinico dell’esame di laboratorio: l’esempio dell’albumina sierica
Measurement accuracy and clinical use of laboratory tests: the case of serum albumin
<p>Albumin is the major plasma protein and its determination is used for the prognostic assessment of several diseases. Clinical guidelines call for monitoring of serum albumin with specific target cut-offs that are independent of the assay used. This requires accurate and equivalent results among different commercially available methods (i.e., result standardization) through a consistent definition and application of a reference measurement system. This should be associated with the definition of measurement uncertainty goals based on medical relevance of serum albumin to make results reliable for patient management. In this paper, we show that, in the current situation, if one applies the analytical goals for serum albumin measurement derived from its biologic variation, the uncertainty budget derived from each step of the albumin traceability chain is probably too high to fulfil the established quality levels for albumin measurement and to guarantee the accuracy needed for clinical usefulness of the test. The situation is further worsened if non-specific colorimetric methods are used for albumin measurement as they represent an additional random source of uncertainty.</p>
Biochimica Clinica ; 37(1) 48-52
Opinioni - Opinions
Valutazione dell’impatto del processo di standardizzazione sulla qualità della misura della creatininemia nei laboratori italiani
Evaluation of the impact of standardization process on the quality of serum creatinine determination in Italian laboratories
<p style="text-align: justify;">Evaluation of the impact of standardization process on the quality of serum creatinine determination in Italian laboratories. Creatinine determination in serum is a key indicator of kidney glomerular function. A reference measurement system for standardization of creatinine measurements is now available and virtually all IVD manufacturers have aligned their creatinine assays to this system. The aim of this work was to verify if and how these standardization efforts have improved the state of the art of creatinine determination in Italy through the analysis of Prolarit EQAS results using control materials with target values assigned by a traceable method (enzymatic assay calibrated against the NIST SRM 967). Results obtained during 2006, 2010, and 2011 schemes by participating laboratories showed a general good alignment at creatinine concentrations <span style="font-family: symbol;">&#61566;</span>2.00 mg/dL, with 2011 results &#8211; except for one method group &#8211; well inside the desirable bias (<span style="font-family: symbol;">&#61617;</span>4%). At higher concentrations, whereas the overall bias was small in 2010, for some groups using alkaline picrate (AP) methods it became significantly negative in 2011. The performance markedly worsens at creatinine physiologic concentrations, where a significant positive bias (up to <span style="font-family: symbol;">&#61566;</span>20%) is still present for most of the AP-based analytical systems. Unexpectedly, with few exceptions, no evident improvement in individual assay bias was noted from pre- (2006) to post-standardization (2011) periods. The enzymatic method groups were the only always presenting an acceptable bias for all concentration levels, in addition to showing the lowest between-laboratory variability. The number of laboratories using enzymatic methods, however, still remains only 7% of the total. In conclusion, our EQAS performance data indicate that most of the current "standardized" creatinine methods based on AP reaction do not perform well, mainly at the lower creatinine concentrations. This inaccuracy of creatinine measurements can adversely impact the estimation of glomerular filtration rate by equations and the evaluation of kidney function in pediatrics.</p>
Biochimica Clinica ; 36(6) 414-424
Contributi Scientifici - Scientific Papers
Teoria e pratica degli intervalli di riferimento riferibili
Theory and practice of traceable reference intervals
<p>An issue associated with standardization efforts is the need to develop useful reference intervals. Lack of proper reference intervals may indeed hamper the implementation of standardization in Laboratory Medicine as standardization can modify analyte results and, without adequate reference intervals, this can impair the result interpretation. Once defined, reference intervals obtained with analytical procedures that produce results traceable to the corresponding reference system can be transferred among laboratories, providing that they use commercial assays that produce results traceable to the same reference system and populations have the same characteristics. Multicenter studies are needed for a robust definition of traceable reference intervals, using experimental protocols that include well defined prerequisites. Particularly, employed methods must produce results that are traceable to the reference system for that specific analyte. Thus, the trueness of laboratories producing reference values should be verified and, if necessary, experimental results corrected in accordance with correlation results wit h the selected reference. If requirements in the adoption of traceable reference intervals are fulfilled, the possibility of providing reference intervals that are applicable to any laboratory, able to produce results traceable to the reference system, is realistic. The definition of traceable reference intervals should hopefully cause the disappearance of different reference intervals employed for the same analyte, providing more effective information to clinicians.</p>
Biochimica Clinica ; 36(3) 171-176
Rassegna - Reviews
Il "Joint Committee for Traceability in Laboratory Medicine" (JCTLM): una cooperazione internazionale per promuovere la standardizzazione dei risultati in Medicina di Laboratorio
The Joint Committee for Traceability in Laboratory Medicine (JCTLM): a global cooperation to promote the standardisation of test results in Laboratory Medicine
Biochimica Clinica ; 35(5) 377
Valutazione della sensibilità diagnostica per l'infarto miocardico senza sopraslivellamento del tratto ST (NSTEMI) di due metodi ad alta sensibilità per la troponina cardiaca
Evaluation of the sensitivity of two highly sensitive troponin assays for early detection of non ST-elevation myocardial infarction (NSTEMI).
Biochimica Clinica ; 35(3) 186
Stima dell'incertezza della misura della concentrazione di attività catalitica dell'alanina amminotransferasi (ALT) nel siero mediante il metodo di riferimento IFCC
Calculation of uncertainty of measurement of the catalytic activity concentration of alanine amminotransferase (ALT) in serum by the IFCC reference procedure.
Biochimica Clinica ; 35(1) 20
Standardizzazione in enzimologia clinica: una sfida per la teoria della riferibilità metrologica
Standardization in clinical enzymology: a challenge for the theory of metrological traceability
Biochimica Clinica ; 34(2) 96