Standardizzazione in enzimologia clinica: una sfida per la teoria della riferibilità metrologica

Ilenia Infusino*, Ferruccio Ceriotti, Mauro Panteghini

*Centro Interdipartimentale per la Riferibilità Metrologica in Medicina di Laboratorio (CIRME), Università degli Studi, Milano

Biochimica Clinica: 2010;34(2):96-102 [Article in italian]

ABSTRACT. Standardization in clinical enzymology: a challenge for the theory of metrological traceability. The goal of standardization for measurements of catalytic concentrations of enzymes is to achieve comparable results in human samples, independent of the reagent kits, instruments, and laboratory where the assay is carried out. To pursue this objective, the IFCC has established reference measurement systems for the most important clinical enzymes. These systems are based on the following requirements: a) reference methods, well described in procedures that are extensively evaluated; b) suitable reference materials; and c) reference laboratories operating in a highly controlled manner. Using these reference systems appropriately, the diagnostic industry can assign traceable values to commercial calibrators. Clinical laboratories, which use routine procedures with validated calibrators to measure human specimens, can finally obtain values which are traceable to higher-order reference procedures. These reference systems constitute the structure of the traceability chain to which the routine methods can be linked via an appropriate calibration process, provided that they have a comparable specificity (i.e., they are measuring the same catalytic quantity).

Clinical utilization of natriuretic peptide determination in acute congestive heart failure

Bruna Lo Sasso, Chiara Bellia, Antonietta Caruso, Rosalinda Raineri, Carmelo Migliorisi, Patrizia Maiorana, Giulia Bivona, Marcello Ciaccio

Chair of Clinical Biochemistry, Department of Medical Biotechnologies and Forensic Medicine, Faculty of Medicine, University of Palermobr />
Biochimica Clinica: 2010;34(2):103-106 [Article in english]

ABSTRACT. Natriuretic hormones are a family of vasoactive peptides with many powerful physiological properties and have emerged as highly effective biomarkers in cardiovascular disease. In particular, the B-type natriuretic peptide (BNP) and the N-terminal fragment of proBNP (NT-proBNP) are natriuretic peptides secreted by the cardiac ventricles as a response to plasma volume expansion, pressure overload and resulting ventricular wall distension. Their determination has revolutionized the approach to diagnosis and management of acute heart failure over the past decade, having shown additive diagnostic value to clinical judgment in the evaluation of patients with acute dyspnea. Moreover, the prognostic value of BNP and NT-proBNP has been established in several studies, providing a useful addition to clinical assessment for risk stratification of patients with acute heart failure. This review summarizes the current evidence concerning the clinical utilization of natriuretic peptides in acute congestive heart failure.

B-type natriuretic peptides and thyroid disease

Valentina Randazzo, Giulia Bivona, Bruna Lo Sasso, Antonietta Caruso, Valeria Lapaglia, Loredana Schillaci, Patrizia Maiorana, Rosalinda Raineri, Lucia Liga, Carmelo Migliorisi, Chiara Bellia, Marcello Ciaccio

Chair of Clinical Biochemistry, Department of Medical Biotechnologies and Forensic Medicine, Faculty of Medicine, University of Palermo

Biochimica Clinica: 2010;34(2):107-109 [Article in english]

ABSTRACT. Natriuretic peptide hormones, a family of vasoactive peptides with many favorable physiological properties, have emerged as useful markers in cardiovascular disease. In particular, B-type natriuretic peptide (BNP) is a cardiac neurohormone secreted by the left cardiac ventricle as a response to ventricular volume expansion, pressure overload and resultant increased wall tension, directly correlated with both left ventricular filling and pulmonary wedge pressure. It is nowadays considered an important diagnostic tool, adding information to clinical judgment in the evaluation of patients with acute dyspnea and a potential guide to the treatment of chronic heart failure. Moreover, the prognostic value of BNP has been established in several studies, both in post-myocardial infarction patients with asymptomatic left ventricular dysfunction and in patients with overt heart failure. A wide spectrum of cardiac changes is observed in thyroid dysfunctions. In this paper we review the relationship between natriuretic peptide concentrations and different thyroid states.

Molecular characterization of Philadelphia-negative myeloproliferative neoplasms

Angela Brisci, Daniela Pietra, Barbara Foglieni, Sabrina Boggi, Elisa Rumi, Francesco Passamonti, Maurizio Ferrari, Laura Cremonesi*

*Genomic Unit for the Diagnosis of Human Pathologies, Center for Genomics, Bioinformatics and Biostatistics, San Raffaele Scientific Institute, Milano

Biochimica Clinica: 2010;34(2):107-114 [Article in english]

ABSTRACT. A somatic gain-of-function mutation in exon 14 of the Janus kinase 2 (JAK2) gene is found in Philadelphia-negative myeloproliferative neoplasms, which include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Hematopoietic cells can be either heterozygous or homozygous for JAK2 (V617F) mutation, producing variable proportions of mutant alleles and a relation was observed between mutation status and clinical phenotype. Moreover, while the vast majority of patients with PV carry the V617F mutation in JAK2 exon 14, mutations in exon 12 have been recently reported in V617F-negative patients with PV. For the evaluation of granulocyte JAK2 (V617F) mutation status, we developed both a quantitative real-time polymerase chain reaction (PCR)-based and a microelectronic chip assay as a model of microarray-based approach. A significant correlation was found between the percentages of JAK2 (V617F) mutant alleles estimated by the two methods. However, the real-time PCR approach proved to be more sensitive in the detection of the minority mutant allele than the microelectronic chip. To further characterize JAK2 exon 12 mutations, we performed analysis in 128 patients with JAK2 (V617F)-negative myeloproliferative neoplasms. Direct sequencing analysis of JAK2 exon 12 led to the identification of five different mutations in cases where the levels of the mutated alleles were higher than 10%.

Inchiesta nazionale sull’impiego di metodi commerciali basati sul principio analitico raccomandato dall’IFCC per la determinazione dell’attività catalitica degli enzimi nel siero

Giampaolo Cattozzo*, Maurizio Borsotti, Anna Carobene, Loredana Incorvaia, Sandra Secchiero, Carlo Franzini per il Gruppo di Studio SIBioC Enzimi
*Azienda Ospedaliero-Universitaria Ospedale di Circolo e Fondazione Macchi, Varese

Biochimica Clinica: 2010;34(2):115-119 [Article in italian]

ABSTRACT. National survey on the use of commercial assays employing method principles in agreement with IFCC reference methods for the measurement of catalytic activity of serum enzymes. Method-dependent variability of enzyme catalytic activities jeopardizes the use of uniform clinical decision limits and confuses the understanding of results observed in patient sera and in control materials as well. Results by different methods may be harmonized making the results they produce traceable to a selected higher metrological level: however, it may be easier to achieve result traceability by widespread use of one selected analytical principle comparable with a reference, i.e. the IFCC, reference procedure. The aim of this work was to check the spread in Italian laboratories of assays based on IFCC reference method principles for measurement of alanine transaminase (ALT), -amylase (AMY), aspartate transaminase (AST), creatine kinase (CK), -glutamiltransferase (GGT), and lactate dehydrogenase (LDH) activities. By distributing a questionnaire to organizers of five national EQAS, we collected information about the enzyme analytical methodologies selected in about 1400 laboratories. We found that 86%, 44%, 15% and 10% of laboratories adopted the relevant IFCC principle for CK, AMY, LDH and AST/ALT measurements, respectively. For GGT we observed that the IFCC principle was adopted by 56% of laboratories participating in the two EQAS distinguishing a specific group for the IFCC method. However, 83% of the laboratories participating in EQAS used L--glutamyl-3-carboxy-4-nitroanilide as substrate.