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Selecting appropriate laboratory tests based on available evidence is central to improve clinical effectiveness and impacting on patient outcome. Although long studied, there is no mutual agreement upon pleural fluid (PF) management in the laboratory context. Given the experienced confusion about the real contribution of laboratory investigations to guide clinical interpretation, in this update, we tried to identify useful tests for the PF analysis, aiming to unravel critical points and to define a common line in requesting modalities and practical management. We performed a careful literature review and a deepened study on available guidelines to finalize an evidence-based test selection, intended for clinicians' use to streamline PF management. The following tests depicted the basic PF profile routinely needed: (1) abbreviated Light's criteria (PF/serum total protein ratio and PF/serum lactate dehydrogenase ratio) and (2) cell count with differential analysis of haematological cells. This profile fulfils the primary goal to determine the PF nature and discriminate between exudative and transudative effusions. In specific circumstances, clinicians may consider additional tests as follows: the albumin serum to PF gradient, which reduces exudate misclassification rate by Light's criteria in patients with cardiac failure assuming diuretics; PF triglycerides, in differentiating chylothorax from pseudochylothorax; PF glucose, for identification of parapneumonic effusions and other causes of effusion, such as rheumatoid arthritis and malignancy; PF pH, in suspected infectious pleuritis and to give indications for pleural drainage; and PF adenosine deaminase, for a rapid detection of tuberculous effusion. [ABSTRACT FROM AUTHOR]

This letter, published in the Annals of Clinical Biochemistry, discusses the measurement uncertainty of serum total carbon dioxide (tCO2) and the impact of closing analyser lids on reducing this uncertainty. The authors conducted experiments using different generations of chemistry analysers and found that closing lids did not consistently reduce measurement variance. They also compared their results to performance specifications for maximum allowable standard measurement uncertainty and found that only the Architect platform met the minimum quality goal. The authors recommend that manufacturers focus on improving the analytical quality of tCO2 measurements to reduce variability. [Extracted from the article]

This letter discusses the evaluation of a monoclonal antibody-based immunoturbidimetric assay, Elaprest Turbo, for measuring faecal pancreatic elastase-1 (PE1) on the Optilite analyser. The authors compared the performance of Elaprest Turbo with the ScheBo PE1 ELISA stool test, which is currently used in their laboratory. The results showed good diagnostic agreement between the two assays, indicating that Elaprest Turbo could be a valid alternative for rapid analysis of PE1. The authors also noted that Elaprest Turbo, based on monoclonal antibodies, may have advantages over the polyclonal antibody-based assay in terms of specificity and cross-reactivity with porcine elastase. Overall, Elaprest Turbo offers automation, improved workflow management, reduced turnaround time, and a wider linearity range for PE1 determination. [Extracted from the article]

The National Institute for Health and Clinical Excellence (NICE) guidelines have sparked hot debate regarding the role of carbohydrate antigen 125 (CA-125) for ovarian cancer (OC) detection. Recent literature and evidence calls into question the use of CA-125 in diagnostic algorithms, given the better performance of human epididymis protein 4 (HE4) vs. CA-125 to rule OC. This is an important consideration since combined measurements are not cost-effective. The quality of this evidence is, however, threatened by important gaps related to study design, enrolled populations and analytical issues. For instance, despite the clinical need to prioritize the evaluation of biomarker performance in early stage tumours, sound evidence on this cannot be provided. In addition, results should be cautiously interpreted due to wide differences in the type of employed assays and in adopted diagnostic thresholds for HE4. Comparability among results obtained by different commercially available HE4 assays, together with an objective establishment of analytical goals is essential for the optimal clinical application of this marker. [ABSTRACT FROM PUBLISHER]

New facts have recently enhanced interest in the topic of reference intervals. In particular, the International Organization for Standardization standard 15189, requesting that 'biological reference intervals shall be periodically reviewed', and the directive of the European Union on in vitro diagnostic medical devices asking manufacturers to provide detailed information on reference intervals, have renewed interest in the subject. This review presents an update on the topic, discussing the theoretical aspects and the most critical issues. The basic approach to the definition of reference intervals proposed in the original International Federation of Clinical Chemistry documents still remain valid. The use of data mining to obtain reference data from existing databases has severe limitations. New statistical approaches to discard outliers and to compute reference limits have been recommended. On the other hand, perspectives opened by the improvement in standardization through the implementation of the concept of traceability suggest new models to define 'common' reference intervals that can be transferred and adopted by different clinical laboratories in order to decrease the proliferation of different reference intervals not always justified by differences in population characteristics or in analytical methodology. [ABSTRACT FROM AUTHOR]

We evaluate a new assay reagent for lipase determination, based on the use of 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6'-methylresorufin) ester (DGGR) as substrate. DGGR is cleaved by lipase, resulting in an unstable dicarbonic acid ester which is spontaneously hydrolysed to yield glutaric acid and methylresorufin, a bluish-purple chromophore with peak absorption at 580nm. The rate of methylresorufin formation is directly proportional to the lipase activity in the sample. Bile salts, colipase and calcium chloride are included to provide optimal reactivity and specificity. Analysis of total imprecision gave a coefficient of variation of between 5·7% and 9·6%. Anticoagulants, common interfering substances and carboxylesterase had no effect on the assay, but interference by increased concentrations of serum triglycerides was noted. Good correlations were obtained with turbidimetry and a coupled enzymatic method. The estimated reference interval was 6-38U/L. The unique characteristics of the chromogenic substrate qualify the present method as an innovative approach to serum lipase analysis. [ABSTRACT FROM AUTHOR]

Background: Monitoring of test imprecision is one of the most important quality indicators in clinical laboratories. Imprecision goals should be derived from biological variation. The aim of this study was to evaluate the imprecision of eight tumour biomarker assays routinely measured on the Modular E170 system. Methods: Method coefficient of variations (CVs) were obtained by an appropriate Internal Quality Control programme based on the measurement every working day of a fresh-frozen human serum pool with biomarkers concentrations around the clinical cut-offs. We evaluated data collected along the whole year 2008 (n range: 21-461); monthly CVs and their cumulative means were calculated and compared with corresponding goals. Results: Biomarkers concentration means and average yearly CVs (desirable goals in parentheses) were as follows: α-fetoprotein, 9.6 μg/L, 3.9% (6.0%); CA125, 41.2 U/L, 2.8% (12.4%); CA15.3, 32.7 U/L, 3.1% (3.1%); CA19.9, 35.1 U/L, 2.8% (8.0%); CEA, 7.7 μg/L, 4.3% (6.4%); prostate-specific antigen (PSA), 4.1 μg/L, 4.3% (9.1%); CYFRA 21.1, 2.4 μg/L, 5.7% (11.3%); and ferritin, 64.5 μg/L, 4.0% (7.1%). Conclusions: Our study shows that in routine laboratory practice and over a clinically and analytically relevant time-span, the imprecision of the tumour biomarker measurements on the Roche Modular E170 fulfills desirable goals. For four assays (CA125, CA19.9, PSA and CYFRA 21.1) the optimum CV can even be achieved. [ABSTRACT FROM AUTHOR]

The article discusses research being done on plasma glucose (PG) measurement. It references the study "Italian Joint StBioC-SIPMeL Study Group on Diabetes Mellitus. Glucose Sampling: Importance of Citrate" by M. Carta et al. in the May 5, 2016 issue. The variables considered including the percentage of outpatients with fasting PG, the use of citrate tubes and the effect of a novel approach to specimen collection on the results.

Background: We evaluated the sandwich enzyme-linked immunosorbent assay (ELISA) MARKIT®-M for the determination of heart fatty-acid-binding protein (H-FABP). Results and Conclusions: The between-run coefficient of variation of this assay was <3·9 and it showed good correlation with a previously established ELISA method. The upper reference limit in 30 healthy individuals was 6·1 μg/L. Admission serum H-FABP was evaluated against myoglobin in 41 patients with suspected myocardial infarction (onset of symptoms &les; 5 h). H-FABP showed the same diagnostic efficiency as myoglobin [area (standard error) under the receiver operating characteristic curve: 0·798 (0·079) for H-FABP, 0·771 (0·085) for myoglobin, P = 0·55]. However, using the upper reference limit as decision cut-off, the sensitivity for H-FABP [91%; 95% confidence interval (CI): 76-98%] was significantly (P = 0·019) higher than that of myoglobin (65%; 95% CI: 47-80%). [ABSTRACT FROM AUTHOR]