[SFBC Working Group on sources of errors in laboratory medicine: objectives and key areas of work]. / Groupe de travail SFBC Sur les sources d'erreurs en biologie clinique: Objectifs et axes de travail.

Laboratory medicine plays a crucial role in patient care, contributing to approximately 70 % of clinical decisions. In collaboration with clinicians, laboratory medicine specialists perform analyses that are useful for diagnosis, screening and prevention. Laboratories are known for their efficiency, which is reached through a rigorous quality system. However, errors can occur, especially given the complexity of the total testing process. These errors may lead to severe consequences, such as incorrect diagnoses or delays in treatment. Errors can occur at every stage of the total testing process, those related to the pre-analytical phase being the most prevalent. To reduce medical errors related to laboratory processes, it is essential to provide training for medical and paramedical staff, optimize production automation, and leverage technological advancements. These considerations have led to the creation of a French Working Group on Sources of Errors in Laboratory Medicine, under the aegis of the French lean society of clinical chemistry and laboratory medicine (Société Française de Biologie Clinique - SFBC). The objectives of this working group are to produce an educational handbook on sources of errors in laboratory medicine, provide training for clinical chemists, and conducting applied research projects to better understand the mechanisms behind specific errors. Ultimately, the aim is to minimize errors and enhance the quality of laboratory tests.

Preanalytical, analytical and postanalytical considerations in circulating microRNAs measurement.

Microribonucleic acids (miRNAs) have emerged as a new category of biomarkers for many human diseases like cancer, cardiovascular and neurodegenerative disorders. MicroRNAs can be detected in various body fluids including blood, urine and cerebrospinal fluid. However, the literature contains conflicting results for circulating miRNAs, which is the main barrier to using miRNAs as non-invasive biomarkers. This variability in results is largely due to differences between studies in sample processing methodology, miRNA quantification and result normalization. The purpose of this review is to describe the various preanalytical, analytical and postanalytical factors that can impact miRNA detection accuracy and to propose recommendations for the standardization of circulating miRNAs measurement.

[Measurement of angiotensin-I-converting enzyme in the blood: help for method validation]. / Dosage de l'enzyme de conversion de l'angiotensine-I sanguine : aide à la validation de méthode.

Blood angiotensin-converting enzyme (ACE) assay is now realized by the determination of enzyme activity on synthetic substrate, mostly furylacryloyl-phenylalanyl-L-glycyl-L-glycine (FAPGG). The matrix can be serum or heparin-plasma, with or without a separator; the assay developed on serum or plasma is not adapted to other matrix such as cerebrospinal fluid where the ACE activity is much lower. This assay has been adapted on a number of automated biochemistry analyzers with the specifications of the supplier of reagents, sometimes with modification of volumes or times for analysis. Samples can be stored at +4̊C for at least for one week, freezing at -20̊C is possible but refreezing is not advised. The assay is linear from 10 to 200 UI/L. Fidelity is excellent after calibration of the assay. Accuracy can be calculated from IQA and EQA results, and the analytical uncertainty is between 2% and 5% in function of the serum ACE value. Usual values will be soon available from studies on age brackets and sex, because ACE activity seems to be more elevated in boys during adolescence. At signature, it is interesting to have medical information on the diagnosis of sarcoidosis or its treatment including ACE inhibitors as a proof of intake; we can give a commentary on elevation of serum ACE activity from other causes than sarcoidosis and the causes for low activities.

Glycated albumin.

Glycated hemoglobin (HbA1c) is the reference test for long-term glucose monitoring. However, HbA1c is not recommended in several situations such as hemoglobinopathies, pregnancy or chronic kidney disease. The quantification of serum glycated albumin (GA) can serve as an alternative in these situations. In fact, serum albumin may undergo structural changes by glycation which impacts on its function and plays a major role in the genesis of diabetes mellitus complications. GA can be measured accurately either on serum or plasma collected on tubes containing lithium heparin or EDTA as anticoagulant. The introduction of a new enzymatic assay has increased the diffusion of this test, in both research and clinical settings. This enzymatic assay is rapid, sensitive and adaptable on routine clinical chemistry analyzers. GA allows an evaluation of the glycemic balance over a period of approximately three weeks, and it is particularly interesting for diabetic patients with chronic kidney disease.

Circulating microRNAs as novel biomarkers of Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disorder. Biomarkers could help identify patients at risk and define stages of this disease. Furthermore, biomarkers can be used to evaluate the efficiency of therapeutic agents under testing and thus accelerate the therapeutic discovery process. Biological exploration of AD is currently based on the measurement of ß amyloid peptides, tau and phospho-Tau proteins in cerebrospinal fluid. However, these tests have many limitations. So, the search for new biomarkers is very active. The ability of microRNAs (miRNAs) to regulate neuronal processes by acting as molecular switches in combination with their region specificity make that researchers are interested in miRNAs for their potential uses as biomarkers and as a treatment for neurodegenerative diseases including AD. This literature review aims to take stock of the use of circulating miRNAs as a novel biomarkers for AD.

[The microRNAs as biomarkers: What prospects?] / Les microRNA comme biomarqueurs : quelles perspectives ?

MicroRNAs are nucleic acids of about twenty nucleotides that regulate about a third of the genome at the post-transcriptional level. Thanks to their different forms of transport, microRNAs are stable and can be detected in biological fluids such as blood, urine, cerebrospinal fluid, or saliva. In addition, the profile of circulating microRNAs is a specific part of the cells in which it is secreted and is modified according to the physiological or pathological conditions of these cells. MicroRNAs therefore appear as biomarkers of interest for many diseases. However, these applications face several challenges because there are currently considerable differences between the sample processing procedures, assay methods, and especially the result standardization strategies. This literature review aims to take stock of the current use of microRNAs as biomarkers mainly in biological fluids and address the perspectives that emerge from the fact that their vesicular circulating forms could be used to assess the state of the cells and the tissues that produce them.

Role of mass spectrometry in steroid assays.

In addition to protein hormones, steroids measurement constitutes the basis of modern endocrinology. Immunoassays have shown their limits in this field. In contrast, mass spectrometry shows an excellent sensitivity and specificity that make it the method of choice for steroids assays. The recent introduction of UHPLC-MS is a major advance which reinforces this position. In fact, mass spectrometry provides a lot of advantages such as determination of certain steroids in saliva, diagnosis of enzyme deficiencies, or measurement of molecules previously inaccessible like aldosterone. However, standardization is still needed to ensure good comparability of results between laboratories. In the future, mass spectrometry should not replace the immunoassays but rather complement it.