Thromboplastin Related Differences in the Determination of International Normalised Ratio: A Cause for Concern?

1994 ◽  
Vol 72 (03) ◽  
pp. 426-429 ◽  
Author(s):  
S Kitchen ◽  
I D Walker ◽  
T A L Woods ◽  
F E Preston
Keyword(s):  
Patient Management ◽  
External Quality Assessment ◽  
Oral Anticoagulant Therapy ◽  
Warfarin Dosage ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
International Normalised Ratio ◽  
The Uk ◽  
The Relationship

SummaryWhen the International Normalised Ratio (INR) is used for control of oral anticoagulant therapy the same result should be obtained irrespective of the laboratory reagent used. However, in the UK National External Quality Assessment Scheme (NEQAS) for Blood Coagulation INRs determined using different reagents have been significantly different.For 18 NEQAS samples Manchester Reagent (MR) was associated with significantly lower INRs than those obtained using Diagen Activated (DA, p = 0.0004) or Instrumentation Laboratory PT-Fib HS (IL, p = 0.0001). Mean INRs for this group were 3.15, 3.61, and 3.65 for MR, DA, and IL respectively. For 61 fresh samples from warfarin-ised patients with INRs of greater than 3.0 the relationship between thromboplastins in respect of INR was similar to that observed for NEQAS data. Thus INRs obtained with MR were significantly lower than with DA or IL (p <0.0001). Mean INRs for this group were 4.01, 4.40, and 4.59 for MR, DA, and IL respectively.We conclude that the differences between INRs measured with the thromboplastins studied here are sufficiently great to influence patient management through warfarin dosage schedules, particularly in the upper therapeutic range of INR. There is clearly a need to address the issues responsible for the observed discrepancies.

scholarly journals Local Calibration of International Normalised Ratio Improves between Laboratory Agreement: Results from the UK National External Quality Assessment Scheme

1999 ◽  
Vol 81 (01) ◽  
pp. 60-65 ◽  
Author(s):  
I. Jennings ◽  
T. A. L. Woods ◽  
F.E Preston ◽  
S. Kitchen ◽  
Keyword(s):  
External Quality Assessment ◽  
Local System ◽  
Calibration Graph ◽  
Calibration Model ◽  
Local Calibration ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Measurement Systems ◽  
International Normalised Ratio ◽  
The Uk

SummaryIn the present study we have performed local calibration of International Normalised Ratio (INR) measurement systems in a large series of laboratories. We assigned INRs to five lyophilised plasma calibrants, one prepared from normal plasma and four using plasma from war-farinised patients, using different International Reference Preparations for Thromboplastin. These five calibrants, and two lyophilised test plasmas were analysed by 349 centres using 60 different thromboplastin instrument combinations.Plasma calibrants were assigned INRs using the WHO reference thromboplastin RBT-90 or the European reference thromboplastin CRM 149R. Each participating centre determined PTs of the calibrants with their local system. These PTs were then used to construct a local calibration graph relating PT to INR. The PTs of test plasmas were converted directly into INR using the local calibration model and into INR using the conventional method. The overall medians of conventionally derived INRs of two test plasmas analysed in 349 centres were 2.50 and 3.10, compared to 2.47 and 3.04 after local calibration where RBT-90 was employed to assign INRs to calibrants. Use of CRM 149R to assign INRs to calibrants led to a significant (p <0.0001) increase in INR to 2.7 and 3.36 respectively. When results were grouped according to the thromboplastin employed, agreement between results with different reagents was improved by local calibration. There was a significant reduction (p <0.01) in the spread of results in different centres as indicated by a reduction in coefficient of variation.

Assessment of the correctness of identification and determination of antimicrobial susceptibility of Streptococcus pneumoniae in microbiological laboratories in Poland

2020 ◽  
Vol 55 (4) ◽  
pp. 271-276
Author(s):  
Ewa Młodzińska ◽  
Waleria Hryniewicz
Keyword(s):  
Quality Control ◽  
Antimicrobial Susceptibility ◽  
Bacterial Resistance ◽  
External Quality Assessment ◽  
Resistance Mechanisms ◽  
Medical Problems ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Reliable Identification

The increase in bacterial resistance to antimicrobials is one of the most serious medical problems, therefore reliable identification in microbiological laboratories is important. The Polish National External Quality Assessment Scheme in Microbiological Diagnostics – POLMICRO programme is organized by the Centre of Quality Control in Microbiology (CQCM) enables the assessment of the competence of Polish microbiological laboratories in the field of identification, determination of susceptibility and detection of drug resistance mechanisms. This work presents the assessment of the results of identification and determination of S. pneumoniae antimicrobial susceptibility obtained by Polish laboratories during the 20 years of experience of the POLMICRO programme.

POLMICRO 2014 – Polish National External Quality Assessment Scheme in Microbiological Diagnostics

2015 ◽  
Vol 51 (2) ◽  
pp. 123-130
Author(s):  
Ewa Młodzińska ◽  
Elżbieta Stefaniuk ◽  
Karolina Bosacka ◽  
Beata Chmylak ◽  
Monika Fortuna ◽  
...  
Keyword(s):  
Quality Control ◽  
External Quality Assessment ◽  
Resistance Mechanisms ◽  
Bacterial Isolates ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Microbiological Diagnostics ◽  
Different Types ◽  
Enteric Infections

In 2014 Centre for Quality Control in Microbiology (CQCM)organized two different types of proficiency programmes: one was designed for laboratories providing a broad spectrum of microbiological diagnostics and the second was prepared for laboratories dealing with enteric infections only. The aim of the POLMICRO 2014 programme was to evaluate proficiency of laboratories in the identification of microorganisms, determination of susceptibility to antibiotics and detection of resistance mechanisms. Bacterial isolates distributed within the Programme differed in their susceptibility to antibiotics and a presence of various resistance mechanisms. The paper presents the results of the XXI edition – POLMICRO 2014.

The Polish National External Quality Assessment Scheme in Microbiological Diagnostics – POLMICRO 2017

2018 ◽  
Vol 54 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Ewa Młodzińska ◽  
Karolina Bosacka ◽  
Anna Mikołajczyk ◽  
Joanna Rybicka ◽  
Elżbieta Stefaniuk ◽  
...  
Keyword(s):  
Quality Control ◽  
Quality Assessment ◽  
External Quality Assessment ◽  
Resistance Mechanisms ◽  
Bacterial Isolates ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
Microbiological Diagnostics ◽  
Antibiotics Detection

The Polish National External Quality Assessment Scheme in Microbiological Diagnostics – POLMICRO programme is organized by the Centre of Quality Control in Microbiology (CQCM). The aim of the POLMICRO 2017 Programme was to evaluate proficiency of laboratories in the identification of microorganisms, determination of susceptibility to antibiotics, detection of resistance mechanisms and interpretation of Gram slides. Bacterial isolates distributed within the Programme differed in their susceptibility to antibiotics and presence of various resistance mechanisms. The paper presents the results of the XXIV edition – POLMICRO 2017.

scholarly journals Assays for Follicle Stimulating Hormone and Luteinising Hormone: Guidelines for the Provision of a Clinical Biochemistry Service

1987 ◽  
Vol 24 (3) ◽  
pp. 246-262 ◽  
Author(s):  
G H Beastall ◽  
K M Ferguson ◽  
D ST J O'reilly ◽  
J Seth ◽  
B Sheridan
Keyword(s):  
Quality Assessment ◽  
Luteinising Hormone ◽  
External Quality Assessment ◽  
Follicle Stimulating Hormone ◽  
In Vitro Fertilisation ◽  
Similar Proportion ◽  
External Quality ◽  
External Quality Assessment Scheme ◽  
The Uk ◽  
Stimulating Hormone

The measurement of serum follicle stimulating hormone (FSH) and luteinising hormone (LH), together with the appropriate sex steroid, is of great value in the investigation of delayed and precocious puberty, hypogonadism, subfertility, polycystic ovarian disease and hypothalamic-pituitary disorders. Dynamic function testing of the hypothalamic-pituitary-gonadal axis should be restricted to a few defined situations. Sequential LH measurements, either in serum or in urine, may be used to time ovulation during artificial insemination or in vitro fertilisation programmes. No special precautions are necessary when sampling for FSH and LH measurement; serum is preferred to plasma and should be stored frozen before assay. Aliquots of timed urine specimens of known volume should be stored frozen without preservative. Gonadotropin results should be available within 2–3 weeks; laboratories unable to meet this schedule are advised to send their samples to a Regional Centre for assay. Reagents for the radioimmunoassay of FSH and LH are readily available, and standard techniques have been developed for their use. Laboratories using ‘in-house’ methods should pay particular attention to the matrix used for preparing standard solutions, the purification of radioligands and the optimisation of the separation system. Low cost matched reagents of proven performance are available in kit form from the Chelsea Hospital for Women; several commercial kits are also available, although few are widely used in the UK. The overall performance of laboratories in the UK External Quality Assessment Scheme (EQAS) for FSH and LH has remained steady for several years. Of the 130 participants, only about 15% in each scheme have ‘good’ performance (cumulative bias less than 10%, plus cumulative variability of bias less than 10%), whilst a similar proportion have ‘unacceptable’ performance (cumulative bias greater than 20% and/or cumulative variability of bias greater than 25%). The remaining 70% of laboratories have ‘adequate’ performance but are at risk of producing results that are clinically misleading. Within any one method group, the performance of FSH and LH assays are closely related. Optimal assay performance depends upon sensible laboratory management to ensure skilled operators, a regular programme of reagent/kit renewal, comprehensive internal and external quality assessment, and attention to detail in all aspects of gonadotrophin assay. The working range of each individual assay should be defined and no absolute result reported from outside this range. Mean intra-assay and interassay coefficients of variation on selected human serum quality control pools should be better than 8% and 15%, respectively, for both gonadotrophins. All laboratories performing FSH and LH assays should belong to the UK EQAS for gonadotrophins. Immunometric assays, using monoclonal antibodies, will supersede radioimmunoassays for FSH and LH during the next few years. Some of these assays will have non-isotopic labels.

Sign in / Sign up

Export Citation Format

Share Document