scholarly journals Multicenter harmonization of common enzyme results by fresh patient-pool sera

1998 ◽  
Vol 44 (3) ◽  
pp. 614-621 ◽  
Author(s):  
Paul F H Franck ◽  
Gerard Steen ◽  
Arnold J P F Lombarts ◽  
John H M Souverijn ◽  
Robert K A van Wermeskerken
Keyword(s):  
Creatine Kinase ◽  
Certified Reference Materials ◽  
Parametric Method ◽  
Reference Population ◽  
Reference Laboratory ◽  
Reference Ranges ◽  
Clinical Laboratories ◽  
Individual Laboratory ◽  
The Individual ◽  
Regional Reference

Abstract A region consisting of 19 clinical laboratories harmonized their calibration of seven common enzymes by using fresh patient-pool sera. One of the laboratories was chosen to act as Regional Reference Laboratory (RRL). This laboratory used internationally accepted (mostly IFCC) methods at 37 °C, with an intralaboratory CV ≤2.5%. First, the reference ranges of the RRL were verified by analysis of a reference population and calculation of the results by a parametric method. Next, all laboratories, including the RRL, received six patient-pool sera and analyzed them at the same time on the same date. Enzyme calibration factors at each laboratory were converted on the basis of the slope, and occasionally the intercept, of regression analysis with the RRL and the individual laboratory. Before harmonization, the interlaboratory CVs varied from 16.9% to 61.6%. After harmonization, CVs decreased to between 5.0% and 9.5%. These results proved to be reproducible over a period of more than a year. Using internationally accepted inaccuracy and imprecision criteria, the achieved interlaboratory CVs permit the use of one set of reference ranges by all participating laboratories. Certified Reference Materials were analyzed, resulting in interlaboratory CVs as low as those achieved with patient-pool sera. These materials can act as commutable reference preparations, except for creatine kinase.

Clinical and analytical evaluation of kits for measurement of creatine kinase isoenzyme MB.

1986 ◽  
Vol 32 (1) ◽  
pp. 186-191 ◽  
Author(s):  
T R Koch ◽  
U J Mehta ◽  
H C Nipper
Keyword(s):  
Creatine Kinase ◽  
Clinical Performance ◽  
Reference Population ◽  
Reference Ranges ◽  
Diagnostic Specificity ◽  
Electrophoretic Method ◽  
Reference Limit ◽  
Coronary Care ◽  
Upper Reference Limit ◽  
Creatine Kinase Isoenzyme Mb

Abstract We studied the analytical and clinical performance of six methods for creatine kinase (EC 2.7.3.2) isoenzyme MB (CK-MB): three immunoassays (Behring, Hybritech, and International Immunoassay Labs); one immunoinhibition assay (Roche); one immunoinhibition/column method (Du Pont); and one electrophoretic method (Beckman). Between-day precision for all kits was poor at the upper reference limit. All methods gave results linearly related to CK-MB concentration and all were free from CK-MM, CK-BB, and adenylate kinase interference. Only the Du Pont method was adversely affected by atypical isoenzymes. For diagnosis of acute myocardial infarction in a coronary care population (n = 40; prevalence = 45%), all methods were approximately 95% efficient, when appropriate reference criteria were used. Some manufacturers fail to provide data for an appropriate (acutely ill, non-infarct) reference population; decreased diagnostic specificity may result from use of reference ranges based on results for healthy subjects. Expression of CK-MB as a percent of total CK degrades efficiency unless total CK is markedly increased.

scholarly journals Achieving Congruence among Reference Laboratories for Absolute Abundance Measurement of Analytes for Rare Diseases: Psychosine for Diagnosis and Prognosis of Krabbe Disease

2020 ◽  
Vol 6 (2) ◽  
pp. 29 ◽  
Author(s):  
Zackary Herbst ◽  
Coleman T. Turgeon ◽  
Chad Biski ◽  
Hamid Khaledi ◽  
Nancy B. Shoemaker ◽  
...  
Keyword(s):  
Dried Blood Spots ◽  
Krabbe Disease ◽  
Specific Reference ◽  
Reference Laboratory ◽  
Reference Ranges ◽  
Absolute Concentration ◽  
Standard Curve ◽  
Diagnosis And Prognosis ◽  
Clinical Laboratories ◽  
The Absolute

Measurement of the absolute concentration of the biomarker psychosine in dried blood spots (DBS) is useful for diagnosis and prognosis of Krabbe disease and to support newborn screening of this leukodystrophy. As for assays for more common diseases, it is important to achieve congruence when multiple clinical laboratories provide testing. Four clinical laboratories, one research laboratory, and a commercial vendor collaborated with the goal to achieve congruence in quantitative psychosine measurement in DBS. A set of DBS calibrators was prepared by a single vendor and used in each reference laboratory to make a standard curve of measured psychosine in DBS versus the stated calibrator psychosine level. Congruence between the participating five laboratories was achieved using the psychosine DBS calibrators. This allowed application of disease-specific reference ranges obtained by the reference laboratory with the most extensive data by the other reference laboratories. Congruence between multiple reference laboratories in the measurement of the absolute concentration of biomarkers in DBS (and by extension other samples) is possible by the use of a common set of DBS calibrators.

Proficiency testing for creatine kinase isoenzyme CK-2 (CK-MB) in Ontario

1990 ◽  
Vol 36 (12) ◽  
pp. 2102-2105 ◽  
Author(s):  
M J McQueen ◽  
R L Patten ◽  
A R Henderson ◽  
S Krishnan ◽  
D E Wood ◽  
...  
Keyword(s):  
Creatine Kinase ◽  
Proficiency Testing ◽  
Analytical Methods ◽  
Immunological Methods ◽  
Reference Ranges ◽  
Testing Material ◽  
Creatine Kinase Isoenzyme ◽  
Clinical Laboratories ◽  
Frequency Of Use ◽  
Survey Results

Abstract Three surveys of the measurement and interpretation of creatine kinase (CK; EC 2.7.3.2) isoenzyme 2 (CK-MB) were conducted in Ontario, Canada, in 1989. Of the clinical laboratories participating, 66% used immunological methods and 24% used electrophoretic methods. Although reference ranges and interpretative routines varied widely, 95% of the laboratories reported correct interpretations for 10 of the 15 vials tested. The only major problems occurred with samples with very low total CK activity. Within-survey duplicate results compared well, and 89% of the laboratories had consistent between-survey results, even for specimens with low total CK activity. Errors were proportional to the frequency of use of the different analytical methods. The lyophilized testing material gave higher results with methods for measuring the mass of CK-2, suggesting that the material contained inactive but immunologically intact CK-2. The surveys indicate that laboratories should review their protocols for measuring CK-2 when only a single sample from the patient is available.

Accuracy of Send-Out Test Ordering: A College of American Pathologists Q-Probes Study of Ordering Accuracy in 97 Clinical Laboratories

2008 ◽  
Vol 132 (2) ◽  
pp. 206-210
Author(s):  
Paul N. Valenstein ◽  
Molly K. Walsh ◽  
Ana K. Stankovic
Keyword(s):  
Laboratory Tests ◽  
Error Rates ◽  
Reference Laboratory ◽  
Patient Evaluation ◽  
Order Entry ◽  
Order Accuracy ◽  
Specific Test ◽  
Clinical Laboratories ◽  
Test Order ◽  
Test Ordering

Abstract Context.—Errors entering orders for send-out laboratory tests into computer systems waste health care resources and can delay patient evaluation and management. Objectives.—To determine (1) the accuracy of send-out test order entry under “real world” conditions and (2) whether any of several practices are associated with improved order accuracy. Design.—Representatives from 97 clinical laboratories provided information about the processes they use to send tests to reference facilities and their order entry and specimen routing error rates. Results.—In aggregate, 98% of send-out tests were correctly ordered and 99.4% of send-out tests were routed to the proper reference laboratory. There was wide variation among laboratories in the rate of send-out test order entry errors. In the bottom fourth of laboratories, more than 5% of send-out tests were ordered incorrectly, while in the top fourth of laboratories fewer than 0.3% of tests were ordered incorrectly. Order entry errors were less frequent when a miscellaneous test code was used than when a specific test code was used (3.9% vs 5.6%; P = .003). Conclusions.—Computer order entry errors for send-out tests occur approximately twice as frequently as order entry errors for other types of tests. Filing more specific test codes in a referring institution's information system is unlikely to reduce order entry errors and may make error rates worse.

Clinical Requests for Molecular Tests: The 3-Step Evidence Check

2012 ◽  
Vol 136 (12) ◽  
pp. 1585-1592 ◽  
Author(s):  
Alexis B Carter
Keyword(s):  
Laboratory Tests ◽  
Digital Age ◽  
Molecular Methods ◽  
Molecular Medicine ◽  
Molecular Testing ◽  
Reference Laboratory ◽  
New Wave ◽  
Molecular Test ◽  
Molecular Tests ◽  
The Individual

Laboratory tests performed by molecular methods are increasing in volume and complexity at an unprecedented rate. Molecular tests have a broad set of applications, and most recently have been advocated as the mechanism by which providers can further tailor treatments to the individual patient. As the momentum behind molecular testing continues to increase, pathology practices may find themselves unprepared for the new wave of molecular medicine. This special article has been developed in an effort to provide pathologists who have limited molecular training with a simple and quick algorithm for determining whether a requested molecular test is appropriate for a patient. Additional recommendations for a more intensive and proactive review and management of molecular requests also are included. The principles discussed can easily be applied to requests for any test, including those not using molecular methods, which would be sent to an outside reference laboratory. This special article was developed from a Webinar for the College of American Pathologists targeting education for pathologists about the transformation of pathology practice in the new molecular and digital age.

Abstract 2516: Primary Aldosteronism And Inappropriateness Of Left Ventricular Mass

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Maria Lorenza Muiesan ◽  
Massimo Salvetti ◽  
Anna Paini ◽  
Claudia Agabiti Rosei ◽  
Cristina Monteduro ◽  
...  
Keyword(s):  
Left Ventricular Mass ◽  
Primary Aldosteronism ◽  
Adrenal Adenoma ◽  
Blood Pressure Measurement ◽  
Reference Population ◽  
Left Ventricular ◽  
The Body ◽  
Stroke Work ◽  
Ventricular Mass ◽  
The Individual

Background: The calculation of values of left ventricular mass (LVM) exceeding individual needs to compensate haemodynamic load (inappropriate LVM) can identify patients with high CV risk (de Simone J. Hypertens 2001, Muiesan Hypertens 2007). However, a substantial percentage of LVM variance remains unexplained, even when the influence of cardiac workload, of the body size and gender are taken into account. It is possibile that other factors, non hemodynamic (genetic) or neurohumoral (renin-angiotensin-aldosterone system) may explain the individual LVM. Aim of this study to evaluate the prevalence of inappropriate LVM (iLVM) in patients with primary aldosteronism (PA). Methods 94 PA (51 with adrenal hyperplasia and 43 with adrenal adenoma), (age 49 ± 11 years, 41 F) and in 94 essential hypertensives (EHT) matched for age and sex, underwent echocardiography. The appropriateness of LVM to cardiac workload was calculated by the ratio of observed LVM to the value predicted for an individual gender, height, and stroke work at rest, from a reference population (de Simone et al, 1998). All subjects underwent laboratory examinations, including PRA and plasma aldosterone, and clinic and 24 hours blood pressure measurement. Results No significant differences were observed for clinic and 24 hours BP, clinic and 24 hours heart rate, glucose and lipids between PA and EHT. The prevalence of traditionally defined LV hypertrophy (LVMI ≥ 47 g/m 2.7 in F and 50g/m 2.7 in M) was greater in PA patients than in EHT (48 vs 19 % chi 2 = 0.02). In patients without LVH, the prevalence of iLVM (> 128% of predicted) was also greater in patients with PA than in EHT controls, (14 % vs 2.5 %, chi 2 p = 0.012). Among PA those with iLVM had a higher BMI, increased uric acid, lower midwall fractional shortening, and prolonged isovolumic relaxation time (p < 0.05 at least). In all patients a small, albeit statistically significant, correlation was observed between the Aldosterone/PRA levels and the ratio of observed/predicted LVM (r = 0.18, p < 0.02). Conclusions: In patients with PA the prevalence of iLVM is increased, even in the absence of traditionally defined LVH. The increase in aldosterone levels could contribute to the increase of LV mass exceeding the amount needed to compensate hemodynamic load.

Center for disease control diagnostic immunology proficiency testing program results for 1976

1977 ◽  
Vol 6 (3) ◽  
pp. 224-232
Author(s):  
R N Taylor ◽  
K M Fulford ◽  
A Przybyszewski ◽  
V Pope
Keyword(s):  
Disease Control ◽  
Proficiency Testing ◽  
Hepatitis B Surface Antigen ◽  
Testing Program ◽  
Proficiency Levels ◽  
Clinical Laboratories ◽  
Individual Laboratory ◽  
Specific Proteins ◽  
Overall Performance ◽  
Testing Protocols

Over 900 laboratories participated in the Diagnostic Immunology portion of the 1976 Proficiency Testing Program, which was provided by the Center of Disease Control under the authority of the Clinical Laboratories Improvement Act of 1967. One hundred specimens prepared by the Center for Disease Control for analysis were distributed on a quarterly schedule or in special surveys. Feedback from participating laboratories included over 37,500 qualitative and 33,000 quantitative responses, which were analyzed to determine individual laboratory proficiency levels. In addition, information supplied by participants in each survey helped to delineate trends in testing protocols. The specimens chosen for analysis called for a broad range of tests commonly performed in diagnostic immunology laboratories, including those for rubella antibodies, hepatitis B surface antigen, bacterial antibodies, rheumatoid factor, immunoglobulins and other serum-specific proteins, and carcinoembryonic antigen. A summary of the data analysis is provided so that the laboratories can improve their overall performance levels.

scholarly journals The Influence of Serum Sample Storage Conditions on Selected Laboratory Parameters Related to Oxidative Stress: A Preliminary Study

Diagnostics ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 51
Author(s):  
Lilla Pawlik-Sobecka ◽  
Katarzyna Sołkiewicz ◽  
Izabela Kokot ◽  
Aleksandra Kiraga ◽  
Sylwia Płaczkowska ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Serum Sample ◽  
Storage Conditions ◽  
Wilcoxon Test ◽  
Reference Ranges ◽  
Sample Storage ◽  
Serum Samples ◽  
The Stability ◽  
The Individual ◽  
The Impact

The present work aims at accessing the stability of biological material stored for diagnostic and scientific purposes. The influence of the temperature, storage time, and cyclic thawing on concentration stability of selected oxidative stress parameters in human serum was investigated. The study group consisted of 20 serum samples collected from healthy volunteers aged 18–52. The parameters whose reference ranges were not determined and to which validated determination methods did not correspond were examined by manual methods (FRAP and AOPP). Automatic methods were used to determine routine laboratory tests (albumin, total protein, bilirubin, uric acid) using the Konelab 20i® analyzer. The samples were stored at various temperatures (room temperature, 4 °C, −20 °C, −80 °C) for max 6 months and were subjected to cyclic thawing at 1 month intervals. In order to check whether any differences between the concentrations of the studied parameters existed when the samples were stored in various conditions, the paired Student t-test or Wilcoxon test and comparison to desirable bias were applied. Based on the obtained results, it was found that the temperature and time of serum sample storage significantly affected the stability of the analyzed parameters and determined different shelf lives of serum samples for oxidative stress examination. Therefore, continuing the investigation concerning the impact of storage conditions on various serum parameters seems justified due to the discrepancy between the individual results obtained by different researchers and the inconsistencies between the results of scientific research and the applicable recommendations.

scholarly journals RSV burden among hospitalized patients: 6-years surveillance of Liguria regional reference lab

2019 ◽  
Vol 29 (Supplement_4) ◽  
Author(s):  
F Grammatico ◽  
F Butera ◽  
I G Iavarone ◽  
I Schenone ◽  
C Arcuri ◽  
...  
Keyword(s):  
Surveillance System ◽  
Adult Population ◽  
Respiratory Viruses ◽  
Hospitalized Patients ◽  
University Hospital ◽  
Reference Laboratory ◽  
Rsv Infection ◽  
Syncytial Virus ◽  
Virological Surveillance ◽  
Regional Reference

Abstract Background Respiratory syncytial virus (RSV) represents one of the most common agent causing respiratory infections in infants and adults. It causes seasonal epidemics, with a peak prevalence in winter. RSV epidemiology and burden are still under-recognized, although it leads to complications and increased mortality in patients at risk, such as infants, pregnant women, the elderly and patients with chronic diseases. Materials/Methods Data analyzed in this study were collected during the virological surveillance system activities at the Policlinico San Martino university hospital in Genoa, Italy. The regional reference laboratory receive swabs from all Liguria region, and detects the main circulating respiratory viruses by using molecular methods. The proportion rate of RSV (subtypes A and B) positive samples was determined in the period January 2013 - December 2018, stratifying data by gender, age and hospital units. Results From January 2013 to December 2018, 14911 swabs were analyzed, 585 patients reported at least once RSV positive respiratory sample. The median age of RSV positive patients was 56 years (IQR 27-71), with a males: females ratio of 0.93: 1. The peak RSV infection period occurred mainly during first quarter, confirming the seasonal trend of the virus. Greatest proportion of RSV positive samples were received from hematology-oncology wards (45.2% of isolations) and medicine units (31.9%). From 2013 to 2018 an increase of swabs collection of 207% was observed. Neonatology and pediatrics resulted in the highest rate of positive swabs (above 30%), hemato-oncology departments collected 7932 swabs with 3,3 % resulted positive. Conclusions A virological surveillance system able to detect the principal respiratory viruses circulating in adult population is a key element to better understand the RSV epidemiology and evaluate therapeutical strategies, in view of the availability of effective vaccines able to prevent RSV infection in the next future. Key messages RSV represents a leading cause of respiratory disease in hospitalized patients, especially in hematology-oncology, medicine and intensive care unit wards. Virological surveillance is a key element to better understand RSV epidemiology in all ages, in view of the availability of new effective vaccines.

scholarly journals SAT-166 Advantage and Trustworthy of Cortisol and Dexamethasone Evaluation in Different Biological Matrices in Patients with Adrenal Masses

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Luana Lionetto ◽  
Roberta Maggio ◽  
Pina Lardo ◽  
Donatella De Bernardini ◽  
Fabiola Cipolla ◽  
...  
Keyword(s):  
Salivary Cortisol ◽  
Adrenal Incidentaloma ◽  
Serum Cortisol ◽  
Reference Ranges ◽  
Serum Samples ◽  
Late Night ◽  
Liquid Chromatography Tandem Mass ◽  
Adrenal Masses ◽  
Suppression Test ◽  
The Individual

Abstract Biochemical function of adrenal masses is currently based on 1mg post-overnight dexamethasone suppression test (pDST). Several approaches are recently developed, in order to reduce false positive/negative samples, only in retrospective series. They are based on the correlation of some different parameters, i.e. late-night salivary cortisol (LNSC) vs serum and salivary cortisol pDST; LNSC vs serum and salivary cortisol and serum dexamethasone pDST; LNSC and cortisone vs serum cortisol and salivary cortisol and cortisone pDST. Although these findings offer a better diagnostic performance, several conditions are still disappointed. No information is traceable about the harvest time of diurnal salivary and serum samples and no study include neither the levels of salivary nor urinary dexamethasone pDST. Aim of our study is to combine all these strategies in order to avoid the underestimated biases and obtain more precise information about the true “cortisol condition” of the patients. To reach this purpose we assess both cortisol and dexamethasone concentrations in several samples: saliva at 11PM before the drug administration, diurnal saliva and serum at 8AM and also the urine collection from 11PM to 8AM. Analytes levels are measured using a validated liquid chromatography-tandem mass spectrometry method. In this study we included 20 subjects without morphological adrenal alteration (MRI assessment), dyslipidemia, hypertension and impaired glucose tolerance (healthy controls) and 20 patients with adrenal incidentaloma showing different cortisol levels ranging from normal to ACTH-independent hypercortisolism. In both series, LNSC were similar to salivary cortisol pDST, even if they were greater in the patients with adrenal incidentalomas and subclinical cortisol secretion. Serum dexamethasone levels were in reference ranges, while salivary and urinary dexamethasone found in these matrices require additional sample numbers in order to establish appropriate cut-offs. Our preliminary results suggest that the combination of these findings could represent an improvement to assess the individual cortisol status.

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