At this moment, no urinary components have been associated with false-positive glucose oxidase reactions. Griffith DP, Musher DM, Itin C. Urease. In a short time period, using only a small amount of native uncentrifugated urine, a huge amount of erythrocytes, leukocytes and epithelial cells can be evaluated (4). However, contamination with strong oxidizing cleaning agents peroxide or hydrochloric acid can result in a false-positive reaction. Even the degree of local tissue hypoxia Bright-field microscopy, phase-contrast microscopy or polarized light microscopy are used with low- and high-power magnification. Because of the growing importance of (micro)albuminuria in the diagnosis of kidney disease, more attention has been paid to the particular preanalytical aspects of this analyte. The time lag between voiding and examination of urine is a limiting factor for the over-all diagnostic accuracy. Clin Chem 65(9): 1180-1181. Mayo Medical Laboratories). The accurate standardization of the pre-analytical phase is of pivotal importance for achieving reliable results of coagulation tests and should reduce the side effects of the influence factors. In contrast to manual methods, flow cytometric analysis of casts has an acceptable coefficient of variation of 17% (19). Although 12 mL is the recommended urine volume for adult patients, a range of 512 mL urine is acceptable to examine the formed elements in urine. Urease-positive bacteriuria and obstruction of long-term urinary catheters. Additional requirements may be needed in function of diagnostic procedures (e.g. Pre Automated urinalysis. A sterile collection is mandatory for bacteriological culture of urine samples. WebFactors affecting the usefulness of laboratory data may arise in any of the preanalytical, analytical or post-analytical phase of the testing cycle. Dr. El-Khoury provided valuable insights on managing these pre-analytical errors. An alternative approach to differentiate the bleeding site is based on specific protein analysis, e.g. diagnosis. the quality management process. Stout PR, Klette KL, Horn CK. Preanalytical requirements of urinalysis - PMC - National Center European Laboratory Guidelines for Legally Defensible Workplace Drug Testing, 2003. Post-Analytical Phase - an overview | ScienceDirect Topics The reduction of cast counts depends on the vacuum during aspiration (19). Penders J, Verstraete A. Acta Clin Belg 65(5): 311-318. Clinical Diagnosis and Management by Laboratory Methods. Physiological changes could also modulate other measurements There is a call for novel studies to optimize the analysis of urine sediment. European Confederation of Laboratory Medicine European urinalysis guidelines. Using automated methods for some brands of reagent strips, falsely elevated urinary glucose test strip results can also be caused by elevated urobilinogen concentrations (34). It is mandatory to focus on the preanalytical phase in order to improve the reliability of test results (5) and to lower the costs of health care (6). Urinalysis is the third major diagnostic screening test in the clinical laboratory, only preceded by serum/plasma chemistry profiles and complete blood count analysis (1,2). Common Pre-Analytical Errors in the Lab | Stenberg College and transmitted securely. It is imperative Secondly, sample collection method could The use of the centrifuge brake is contraindicated because of sample resuspension with decreased numbers of urinary formed elements. metabolomics studies and also promote better data sharing Physiological changes could Preanalytical requirements of urinalysis Particle lysis accelerates with increasing pH (too long time lag between collection and analysis, Proteus sp. The available assays measuring Tamm-Horsfall protein can provide information on the presence of casts, without verifying the nature of the casts. These transparent tubes preferably have a round bottom, which allow a better resuspension of the sediment following centrifugation (10). After centrifugation, the specimen analysis can be performed using glass slides or a counting chamber. Several specimen tampering methods have been used to avoid detection: substitution of urine by another fluid, adulteration by addition of a foreign material, dilution of the urine sample by adding water. The pre-analytic testing phase occurs first in the laboratory process. Morning urine specimens should be preferred as correct evaluation of erythrocyte morphology depends on osmolality and pH (46). Table 1A and and1B1B give an overview of the stability of different particles and test strip parameters (22). 1Univ Lille, Inserm, CHU Lille, Institut Pasteur de Lille, France, 2Division of Nutrition, St. Johns Research Institute, St. Johns National Academy of Health Sciences, Bangalore, India, Received: April 30, 2020 | Published: May 11, 2020, Corresponding author: Guillaume Grzych, Univ Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011- EGID, F-59000 Lille, France. Van Acker JT, Verstraete AG, Van Hamme MA, Delanghe J. Falsely increased urinary caffeine attributable to contamination by urine test strips. showed that a 24-hour urine sample was not properly collected in more than half of the informed outpatients, which were often older (mostly > 65 years) and suffering from a chronic disease. A large amount of sampling procedures is available with specific advantages and disadvantages. The recommended specimen volume is mostly indicated on the container with a marking line. Introduction of a project under European Confederation of Laboratory Medicine. However, overnight bacterial growth in the bladder is likely, which can affect casts and cells. To improve the optimal urine quality management in routine clinical laboratories, the CLSI develops best practices in clinical and laboratory testing by using a core set of quality system essentials and promotes the use of these standards worldwide (13). WebAbstract. Components of the pre-analytic phase include sample Influence of preservatives on test strip reactions. Pekar JD, Grzych G, Durand G, Haas J, Lionet A, et al. The same finding in subjects with grossly bloody urine specimens is suggestive of intravascular hemolysis or rhabdomyolysis (40). Belgium. (2019) Transport par pneumatique et fausse hyperkalimie par leucocytose: une tude r Ann Biol Clin (Paris) 77(3) : 281-286. WebThe analytical phase involves the actual running of the test, while the post-analytical phase includes recording the results, interpreting the results, reporting the results to the ordering physician, and filing the report. Finally, level 4 stands for best methods (primary reference measurement procedures = reference and definitive methods). Despite the existing guidelines, the importance of a proper preanalytical procedure for collecting urine specimens is usually not known by the patients. Errors in Binding to surfaces may also result in protein denaturation. 7]. To decrease the incidence of preanalytical problems, several precautions should be taken into account. urinary IgG:albumin and alpha-2-macroglobulin: albumin ratios (47). Besides the analysis of medical samples, some additional requirements are prescribed for forensic specimens: (a) storage of the sample in the original container, (b) minimization of the number of freeze/thaw cycles to reduce specimen degradation, (c) use of control measures to ensure specimen integrity and (d) recordkeeping using internal and external chain-of-custody systems (57). Grzych G, Pekar JD, Maboudou P (2019) Better Glucose Stability in Serum than in Plasma Samples after 12-h Stay at Room Temperature. Vitamin C intake, proteinuria (> 5 g/L), glucosuria (> 20 g/L), 1% boric acid, trypsin inhibitor, oxalate or mercuric salts may decrease the sensitivity of the test (10,34,41). In parallel, a correlation between NGAL and the bacterial count has been reported. Fassett RG, Horgan BA, Mathew TH. Automated flow cytometry compared with an automated dipstick reader for urinalysis. Grzych G, Roland E, Beauvais D, Maboudou P, Lippi G (2019) Leukocytosis interference in clinical chemistry: shall we still interpret test results without hematological data? The European Workplace Drug Testing Society (58), the Substance Abuse and Mental Health Services (59), the Swiss Working Group for Drugs of Abuse Testing Guidelines (60), the Joint Technical Committee (61) and the United Kingdom (62) proposed some criteria for urine validity testing based on several parameters: urinary creatinine concentration, specific gravity, nitrite, pH and presence of exogenous or endogenous substances. which can be influenced by all the variables described above [23]. Firstly, Abstract Objective The objective of this study was to determine the magnitude of pre-analytical, analytical and post-analytical laboratory errors in hematology tests. Since the patients themselves often sample urine specimens, urinalysis is very susceptible to preanalytical issues. Nurses experiences of blood sample collection from children: a False-positive results can also be caused by operator errors, cleaning the skin with isopropyl alcohol, contamination of equipment, specimen confusion, mislabeling and misidentification of the subject, breaks in the chain of custody and errors during the measurement process (57). Pre analytic and postanalytic test management Mostly, microscopy is used for a rough estimate of the amount of figurated elements. Saude EJ, Sykes BD. Due to their impact on the quality of results of laboratory testing, preanalytical errors have been included within the greatest challenges to the laboratory professionals, during the last 20 years ( 1, 2 ). Identification and monitoring of robust quality Analytical Phase Urinalysis and other tests of renal function. Comparing within run CVs for particle analysis between manual methods, automated microscopy (Iris iQ200, Iris Diagnostics Inc, Chatsworth, Los Angeles, CA, USA) and flow cytometry (Sysmex UF-100, Sysmex Corporation, Kobe, Japan) showed that flow cytometry had the best within run CV for erythrocytes, whereas the best within run CV for white blood cells was obtained by automated microscopy (53). WebThe pre-analytical phase is a crucial part of the analysis and is equally important as the analytical component. phase In the clinical laboratory, total quality could be defined as the guarantee of a correctly performed activity throughout the total testing process, providing valuable medical diagnosis and efficient patient care.
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