Alberto Dolci

Biochemical markers for prediction of chemotherapy-induced cardiotoxicity: systematic review of the literature and recommendations for use.

Chemotherapy is a well-established therapeutic approach for several malignancies, but its clinical efficacy is often limited by its related cardiotoxicity, which leads to cardiomyopathy, possibly evolving into heart failure. To detect cardiac damage, the adopted diagnostic approach is the estimation of left ventricular ejection fraction by echocardiography. This approach shows low sensitivity toward early prediction of cardiomyopathy, when the possibilities of appropriate treatments could still improve the patients outcome. Cardiac troponins, however, show high diagnostic efficacy as early as 3 months before the clinical onset of cardiomyopathy. The increase in their concentrations is correlated with disease severity and may predict the new onset of major cardiac events during follow-up. Negative troponin concentrations may identify patients with a very low risk of cardiomyopathy (negative predictive value, 99%). Concerning cardiac natriuretic peptides, definitive evidence in regard to a diagnostic or prognostic role in predicting chemotherapy-induced cardiomyopathy is still lacking.

Recommendations for detection and management of unsuitable samples in clinical laboratories

Abstract A large body of evidence attests that quality programs developed around the analytical phase of the total testing process would only produce limited improvements, since the large majority of errors encountered in clinical laboratories still prevails within extra-analytical areas of testing, especially in manually intensive preanalytical processes. Most preanalytical errors result from system flaws and insufficient audit of the operators involved in specimen collection and handling responsibilities, leading to an unacceptable number of unsuitable specimens due to misidentification, in vitro hemolysis, clotting, inappropriate volume, wrong container or contamination from infusive routes. Detection and management of unsuitable samples are necessary to overcome this variability. The present document, issued by the Italian Inter-society SIBioC-SIMeL-CISMEL (Society of Clinical Biochemistry and Clinical Molecular Biology-Italian Society of Laboratory Medicine-Italian Committee for Standardization of Hematological and Laboratory Methods) Study Group on Extra-analytical Variability, reviews the major causes of unsuitable specimens in clinical laboratories, providing consensus recommendations for detection and management. Clin Chem Lab Med 2007;45:728–36.

Soluble Transferrin Receptor (sTfR) and sTfR/log Ferritin Index for the Diagnosis of Iron-Deficiency Anemia A Meta-Analysis

Determination of serum soluble transferrin receptor (sTfR) is proposed to distinguish between iron-deficiency anemia and anemia of chronic disease. Here we conducted a meta-analysis of the literature to evaluate the diagnostic efficacy of sTfR and sTfR/log ferritin index. The meta-analysis included 18 sTfR and 10 sTfR index studies. Three sTfR index studies were, however, eliminated as outliers. The odds ratio was significant for both sTfR (22.9, 95% confidence interval [CI], 9.6-55.0) and sTfR index (9.5, 95% CI, 5.0-18.1) in a heterogeneous set of studies. Meta-analysis for sensitivity, specificity, and likelihood ratios (LRs) was performed only in a subset of 10 sTfR studies. The overall sensitivity, specificity, and positive and negative LRs were 86%, 75%, 3.85, and 0.19, respectively, with an area under summary receiver operating characteristic curve of 0.912 (standard error, 0.039). Additional studies are needed to define the overall diagnostic accuracy of sTfR.

Harmonization of automated hemolysis index assessment and use: Is it possible?

The major source of errors producing unreliable laboratory test results is the pre-analytical phase with hemolysis accounting for approximately half of them and being the leading cause of unsuitable blood specimens. Hemolysis may produce interference in many laboratory tests by a variety of biological and analytical mechanisms. Consequently, laboratories need to systematically detect and reliably quantify hemolysis in every collected sample by means of objective and consistent technical tools that assess sample integrity. This is currently done by automated estimation of hemolysis index (HI), available on almost all clinical chemistry platforms, making the hemolysis detection reliable and reportable patient test results more accurate. Despite these advantages, a degree of variability still affects the HI estimate and more efforts should be placed on harmonization of this index. The harmonization of HI results from different analytical systems should be the immediate goal, but the scope of harmonization should go beyond analytical steps to include other aspects, such as HI decision thresholds, criteria for result interpretation and application in clinical practice as well as report formats. With regard to this, relevant issues to overcome remain the objective definition of a maximum allowable bias for hemolysis interference based on the clinical application of the measurements and the management of unsuitable samples. Particularly, for the latter a recommended harmonized approach is required when not reporting numerical results of unsuitable samples with significantly increased HI and replacing the test result with a specific comment highlighting hemolysis of the sample.

Revaluation of biological variation of glycated hemoglobin (HbA1c) using an accurately designed protocol and an assay traceable to the IFCC reference system

BACKGROUND Glycated hemoglobin (HbA(1c)) has a key role for diagnosing diabetes and monitoring glycemic state. As recently reviewed, available data on HbA(1c) biological variation show marked heterogeneity. Here we experimentally revaluated these data using a well designed protocol. METHODS We took five EDTA whole blood specimens from 18 apparently healthy subjects on the same day, every two weeks for two months. Samples were stored at -80°C until analysis and assayed in duplicate in a single run by Roche Tina-quant® Gen.2 immunoassay. Data were analyzed by the ANOVA. To assess the assay traceability to the IFCC reference method, we preliminarily carried out a correlation experiment. RESULTS The bias (mean±SD) of the Roche immunoassay was 0.3%±0.7%, confirming the traceability of the employed assay. No difference was found in HbA(1c) values between men and women. Within- and between-subject CV were 2.5% and 7.1%, respectively. Derived desirable analytical goals for imprecision, bias, and total error resulted 1.3%, 1.9%, and 3.9%, respectively. HbA(1c) had marked individuality, limiting the use of population-based reference limits for test interpretation. The estimated critical difference was ~10%. CONCLUSIONS For the first time we defined biological variation and derived indices for the clinical application of HbA(1c) measurements using an accurately designed protocol and an assay standardized according to the IFCC.

Biological variability of glycated hemoglobin.

BACKGROUND The measurement of glycated hemoglobin (HbA(1c)) has a pivotal role in monitoring glycemic state in diabetic patients. Furthermore, the American Diabetes Association has recently recommended the use of HbA(1c) for diabetes diagnosis, but a clear definition of the clinically allowable measurement error is still lacking. Information on biological variability of the analyte can be used to achieve this goal. METHODS We systematically reviewed the published studies on the biological variation of HbA(1c) to check consistency of available data in order to accurately define analytical goals. RESULTS The nine recruited studies were limited by choice of analytic methodology, population selection, protocol application and statistical analyses. CONCLUSIONS There is an urgent need to determine biological variability of HbA(1c) using a specific and traceable assay, appropriate protocol and appropriate statistical evaluation of data.

Biological variation of neuroendocrine tumor markers chromogranin A and neuron-specific enolase

OBJECTIVES Chromogranin A (CgA) and neuron-specific enolase (NSE) are biomarkers for neuroendocrine tumors. Although the knowledge of their biological variation (BV) is critical, only one study for CgA and no data for NSE are available. We report a definitive assessment of BV components of these biomarkers in the same cohort of subjects by an accurately experimental protocol. DESIGN AND METHODS We collected five blood specimens from each of 22 healthy volunteers (10 men and 12 women, 23-54 years) on the same day every two weeks for two months. Serum specimens were stored at -80 °C until analysis and analyzed in a single run in duplicate. Data were analyzed by ANOVA. RESULTS Serum CgA concentrations were significantly higher for women than for men (P=0.01), whereas no difference was found for NSE. Intra-individual variance was not different between genders for both biomarkers. Within- and between-subject CVs were 16.3% and 33.5% for CgA and 13.6% and 11.5% for NSE, respectively. CgA showed marked individuality, suggesting that the use of population-based reference limits is inadequate for its interpretation. Conversely, the low individuality of NSE allows the use of a single reference interval. Reference change values were 46% for CgA and 39% for NSE. Desirable analytical goals for imprecision, bias, and total error were <8.2%, ±9.3%, and ±22.8% for CgA, and <6.8%, ±4.5%, and ±15.7% for NSE, respectively. CONCLUSION In this study, we defined BV components of serum CgA and NSE and derived indices that may improve the clinical use of these biomarkers.

10% CV concentration for the fourth generation Roche cardiac troponin T assay derived from Internal Quality Control data

December 2005 8 1 11.7 0.035 January 2006 18 1 7.6 0.038 February 2006 15 1 9.1 0.037 March 2006 22 2 11.0 0.042 April 2006 20 2 10.9 0.043 May 2006 15 3 5.6 0.048 June 2006 18 3 11.5 0.043 July 2006 20 3 10.7 0.044 Alberto Dolci, Roberto Dominici, Paola Luraschi and Mauro Panteghini* 1 Laboratorio Analisi Chimico-Cliniche, Azienda Ospedaliera ‘‘Luigi Sacco’’, Milan, Italy 2 Cattedra di Biochimica Clinica e Biologia Molecolare Clinica, Dipartimento di Scienze Cliniche ‘‘Luigi Sacco’’, Università degli Studi di Milano, Milan, Italy

Soluble transferrin receptor in complicated anemia.

Determination of serum soluble transferrin receptor (sTfR) has been proposed to identify iron-deficiency anemia (IDA) in patients affected by concurrent inflammatory disease that may spuriously increase ferritin concentration. The aim of this study was to critically review the available literature to assess the diagnostic efficacy of sTfR in complicated anemia. The criteria for study selection were: enrolment of patients with complicated anemia; bone marrow examination used as diagnostic gold standard for IDA; evaluation of sTfR vs. ferritin and binary data presentation. Six published studies met the criteria. However, the small size and wide heterogeneity of the studies did not allow us to conduct a meta-analysis. sTfR was overall more sensitive, even though it was evident that the ferritin sensitivity was influenced by selected cut-offs. Well-designed studies are still needed to define the added value, if any, of sTfR to ferritin for IDA detection in complicated anemia.

Exercise raises serum heat-shock protein 70 (Hsp70) levels.

Heat-shock proteins (Hsps) are highly conserved during phylogenesis, and are ubiquitous in various organisms, including bacteria and humans. Under normal conditions, they act as molecular chaperones, mediating protein folding and transport, and the formation of protein structures essential for cell survival. The synthesis of Hsp is greatly accelerated in cells stressed by heat, infection and other environmental challenges (1). Increased expression of Hsp has been reported in a variety of disorders, such as hypertension, systemic lupus erythematosus, dementia, and cardiovascular and renal diseases (2, 3). In mammals, Hsp70 is associated with the protection of striated muscle from ischemia-reperfusion injury (4) and the attenuation of skeletal muscle atrophy during hindlimb unweighting (5). Hsps help to maintain cellular homeostasis and protein conformation, reactivate denatured or malformed proteins, and provide ‘housekeeping’, translocase and chaperone functions. Some of the conditions known to elicit the cellular stress reaction are similar to those experienced by cells in response to physical exercise. Hyperthermia, ischemia, oxidative, cytokine and muscular stress, glucose deprivation, and alterations in calcium and pH are potent inducers of Hsp expression in different types of cells and tissues (6). Not surprisingly then, the exposure of cells to various sublethal stresses results in an adaptive increase in Hsp70 as a survival mechanism. Exercise is one of the stressors that raises the content of Hsp70 in cardiac and skeletal muscle, but only high-intensity exercise significantly increases Hsp70 (7). Although their action is intracellular, Hsps are released in the extracellular environment and Hsp60 and 70 have both been found in the peripheral circulation in normal individuals (8), but the clinical signif-