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P Rustad

Publications and source records attributed to P Rustad.

14 recordsLinked to original sources
PubMed2004

Reference intervals for eight enzymes in blood of adult females and males measured in accordance with the International Federation of Clinical Chemistry reference system at 37 degrees C: part of the Nordic Reference Interval Project.

As part of the Nordic Reference Interval Project we present reference intervals for alanine transaminase (ALT), aspartate transaminase (AST), creatine kinase (CK), lactate dehydrogenase (LD), alkaline phosphatase (ALP), gamma-glutamyltransferase (GT), amylase (AMY) and pancreatic type of AMY in blood of adult males and females. A total of 3036 reference persons, all of whom considered themselves to be in good health, were recruited by 102 Nordic clinical biochemical laboratories. Exclusions were undertaken on the basis of predefined biochemical and clinical criteria. Enzyme activities in serum and plasma were measured in the different laboratories using various commercially available routine measurement systems at 37 degrees C. Only results obtained with the International Federation of Clinical Chemistry (IFCC) compatible measuring systems were selected for estimation of the enzyme reference intervals. The final number of results on each enzyme varied from 459 (LD) to 2300 (ALT). The 2.5 and 97.5 percentile reference limits were calculated by a non-parametric method in accordance with the IFCC recommendations, using the Refval 4.0 data program. Statistical partitioning testing was undertaken to decide whether the reference intervals ought to be partitioned according to gender and/or age. For most of the enzymes, but not for all, the upper reference limits were found to be higher than those that have been in general use until now.

Adult↗
PubMed2004

The Nordic Trueness Project 2002: use of reference measurement procedure values in a general clinical chemistry survey.

Up to 136 laboratories participated in a joint effort to assess the trueness of routine measurements for 14 serum components. An unmodified, fresh-frozen human serum ("IMEP-17 Material 1"), produced for an international inter-laboratory comparison, served as the "master material". The serum had assigned values of the highest available metrological quality, and is assumed to involve no or negligible commutability problems. The material was used in the assignment of traceable values to two other reference sera, "CAL" and "X", through parallel measurements on the three materials according to a common protocol. In this transfer process, uncertainty estimates were provided for all values. The material CAL had been supplied with reference measurement procedure values in 1997, and the two sets of assigned values agreed well. A lyophilized control serum "HK02" was also included in the routine analysis series. It, too, had assigned values based on reference measurement procedures. Significant matrix effects were found. The project has provided: Assigned traceable values for 14 components in a fresh-frozen serum, available to Nordic laboratories for the coming years as "NFKK reference serum X"; Confirmation of earlier assigned reference measurement procedure values for a number of components in CAL, the main calibrator in the Nordic Reference Interval project (NORIP). The transferred values will now serve as the primary reference.; Evidence of long-term stability ( > or = 5 years) of the fresh-frozen serum CAL when stored at -80 degrees C; Evidence of substantial matrix effects in the processed serum HK02. The findings should be used to discuss to what extent reference measurement procedure values are useful and cost-efficient for this type of material.

Blood Chemical Analysis↗
PubMed2004

Prerequisites for establishing common reference intervals.

Establishment of common reference intervals for homogeneous populations within regions is based on the same basic principles as the IFCC recommendations for individual laboratories, but a few additional prerequisites are needed. Thus, the need for common standardization and traceability during production of the reference values and with the application of the common reference intervals in the laboratories becomes crucial. Furthermore, the external control system must be geared to the purpose, using matrix-correct control materials with concentration values traceable to the same reference methods, and validation of results according to analytical quality specifications designed for the use of common reference intervals. Here, the standards may have a restrictive influence on the establishing of common reference intervals, with their demands for the use of the producers' traceability, instead of a relevant high-quality reference preparation shared by all the participants. Two main strategies for measurements are analysis immediately after the sampling, and storage of samples until analysis in one or a few analytical runs. The former strategy needs constant standardization and stability of the performance in many laboratories and in several analytical runs, resulting in between-run variation, whereas the latter precludes this between-run variation, but makes demands on the stability of the components under storage. When a considerable number of laboratories decide to establish common reference intervals, it is possible to obtain large sample sizes of reference values, which reduces the confidence intervals around the reference limits. It also makes it possible to collect samples from many subgroups, such as racial groups and groups related to different environmental conditions, as well as the traditional groupings according to age and gender, pregnancy and use of oestrogens. If all these subgroups are large, e.g. n>500, the confidence limits will be small and criteria for partitioning can be applied. Choosing reference individuals is not easy, as definitions of health, as well as rule-in and rule-out criteria vary from one investigation to the other. Therefore, the strategy and the criteria must be thoroughly described. Arguments for establishing common reference intervals are not needed. On the contrary, lack of such common reference intervals should be explained.

Chemistry, Clinical↗
PubMed2004

Descriptive analytical data and consequences for calculation of common reference intervals in the Nordic Reference Interval Project 2000.

In the Nordic Reference Interval Project (NORIP), data from 102 Nordic clinical chemical laboratories were obtained. Each laboratory reported analytical data on up to 25 of the most commonly used clinical biochemical properties, including results from each of a minimum of 25 reference individuals. A reference material consisting of a liquid frozen pool of serum with values traceable to reference methods (used as the project "calibrator" for non-enzymes to correct reference values) was measured together with other serum pool controls in each laboratory in the same analytical series as the project samples. The data on the controls were used to evaluate the analytical quality of the routine methods. For reference interval calculations, only such reference values on enzymes were accepted that were obtained by applying the International Federation of Clinical Chemistry (IFCC) compatible methods (37 degrees C), while "calibrator"-corrected reference values were used in the cases of non-enzymes. For each property, gender- and age-specific reference intervals were estimated, based on simple non-parametric calculations and using objective criteria to perform partitioning into subgroups. It is concluded that the same reference intervals are applicable in all five Nordic countries. The following descriptive data for the considered properties are presented in the tables: number of measurement values from each country and measurement system, certified/indicative target values for controls, differences between methods and measurement systems together with coefficients of variation, effects of control correction on the measurement values, differences between subgroups as determined by age, gender, country and material, and comparison of the new reference intervals with those presented in standard textbooks. The 25 components involved in this project were (listed in alphabetical order): Alanine transaminase, albumin, alkaline phosphatase, amylase, amylase pancreatic type, aspartate transaminase, bilirubin, calcium, carbamide, cholesterol, creatine kinase, creatininium, gamma-glutamyltransferase, glucose, HDL-cholesterol, iron, iron-binding capacity, lactate dehydrogenase, magnesium, phosphate, potassium, protein, sodium, triglyceride and urate.

Blood Chemical Analysis↗
PubMed2004

Effect of analytical quality on establishing common reference intervals and their use.

In the Nordic Reference Interval Project (NORIP), reference intervals were established for 25 common clinical biochemical quantities. In the project, samples from more than 3000 reference individuals collected in the 102 participating laboratories from all five Nordic countries were analysed locally. In order to maintain a high level of analytical quality and to document this quality, a common calibrator/reference preparation (CAL) and a number of control samples were analysed together with the reference samples. All these materials were serum pools of unprocessed serum from many donors in order to obtain commutable materials. The CAL was used to harmonize the many different analytical procedures and calibrations by simple recalibration by the factor T/M where T is the target value based on reference methods and M is the mean of 10 replicate measurements of CAL in each laboratory. The analytical quality specifications (analytical goals) were based on specifications created directly for the purpose of sharing common reference intervals and only the bias criteria were used because bias is the dominating problem in transfer of reference intervals. These specifications were different for the evaluation of reference values to create common reference intervals and for the laboratories to use these common reference intervals (when established). An interesting outcome was that it was only for the biologically well-regulated quantities serum-sodium and serum-calcium that the selection of the best laboratories gave considerably narrower reference intervals.

Chemistry, Clinical↗
PubMed2004

The Nordic Reference Interval Project 2000: recommended reference intervals for 25 common biochemical properties.

Each of 102 Nordic routine clinical biochemistry laboratories collected blood samples from at least 25 healthy reference individuals evenly distributed for gender and age, and analysed 25 of the most commonly requested serum/plasma components from each reference individual. A reference material (control) consisting of a fresh frozen liquid pool of serum with values traceable to reference methods (used as the project "calibrator" for non-enzymes to correct reference values) was analysed together with other serum pool controls in the same series as the project samples. Analytical data, method data and data describing the reference individuals were submitted to a central database for evaluation and calculation of reference intervals intended for common use in the Nordic countries. In parallel to the main project, measurements of commonly requested haematology properties on EDTA samples were also carried out, mainly by laboratories in Finland and Sweden. Aliquots from reference samples were submitted to storage in a central bio-bank for future establishment of reference intervals for other properties. The 25 components were, in alphabetical order: alanine transaminase, albumin, alkaline phosphatase, amylase, amylase pancreatic, aspartate transaminase, bilirubins, calcium, carbamide, cholesterol, creatine kinase, creatininium, gamma-glutamyltransferase, glucose, HDL-cholesterol, iron, iron binding capacity, lactate dehydrogenase, magnesium, phosphate, potassium, protein, sodium, triglyceride and urate.

Biomarkers↗
PubMed2004

Reference individuals, blood collection, treatment of samples and descriptive data from the questionnaire in the Nordic Reference Interval Project 2000.

The rules for recruitment of reference individuals, inclusion and preparation of individuals, blood collection, treatment of samples (and control materials) and analysis at the 102 medical laboratories attending the Nordic Reference Interval Project (NORIP) are given as well as the rules for central exclusion of reference individuals. The individuals (18-91-year-olds) should be evenly distributed on age and gender groups. The 3002 reference individuals who contributed at least one reference value to the finally suggested reference intervals were characterized using the information in the questionnaire. Gender, age and country are the main entries in the tables. Other variables in the cross-tables or figure are height, weight, body mass index, ethnic origin, heredity for diabetes, chronic disease, oestrogens or oral contraceptives, other medication, hard physical activity, previous blood donations, smoking habits, use of alcohol, hours since last meal and time of blood collection (hour, day of week, month, year). The Danes had the highest alcohol consumption and the Icelanders had the highest body mass index. The information in this article may interest potential users of the Nordic Reference Interval Project bio-bank and database (NOBIDA) in which serum, Li-heparin plasma and EDTA buffy coat from the mentioned individuals are stored below -80 degrees C.

Adolescent↗
PubMed2004

Nordic Reference Interval Project Bio-bank and Database (NOBIDA): a source for future estimation and retrospective evaluation of reference intervals.

In the Nordic Reference Interval Project 2000 (NORIP) serum, Li-heparin plasma and EDTA buffy coat were collected at 102 laboratories in 5 Nordic countries from healthy individuals aged 18 years or more and evenly distributed for laboratory, gender and age. Multiple aliquots of these samples from each of about 3000 persons are now stored at the Nordic Reference Interval Project Bio-bank and Database (NOBIDA) at a temperature of below -80 degrees C. The commutable NFKK Reference Serum X with certified values traceable to reference methods and measured in NORIP in the same series as the samples is also available from NOBIDA. Data describing the person and the sample conditions are stored together with analytical results and data describing the measurement systems. The bio-bank along with material and data is administered by the NOBIDA committee on behalf of the NFKK (Scandinavian Society of Clinical Chemistry) to be used by Nordic laboratories for any purpose beneficial to the development of clinical biochemistry in general and particularly for creating reference intervals for other biochemical properties than those established by NORIP. Furthermore, research on the already stored information alone is encouraged. Thus colleagues are now welcome to use this extensive material for research and development in clinical biochemistry.

Adolescent↗
PubMed1998

Within-subject biological variation of reticulocytes and reticulocyte-derived parameters.

Automation of reticulocyte counting has decreased the analytical imprecision of this parameter. This has made it possible to use the number of reticulocytes and its derived parameters (reticulocyte maturity and reticulocyte cell indices) in new diagnostic and monitoring situations. For rational use of these parameters, it is important to have knowledge of their biological variability. The biological variability of reticulocytes and its derived parameters was studied in 13 healthy people during a period of 7 wk on 2 different instruments. The within-subject coefficient of variation for the reticulocyte count was about 11%, for the mean reticulocyte volume, mean reticulocyte haemoglobin content and mean reticulocyte haemoglobin concentration it was between 1 and 2%, whereas the coefficient of variations for the subpopulations of reticulocytes with different maturity varied depending on the method used for the measurements. The critical difference, that is the change in a result making it significantly different from the previous result, was about 35% for the reticulocyte count and 5-8% for the reticulocyte cell indices, making these indices excellent to follow changes in erythropoiesis. With a possible exception for the mean reticulocyte volume, the within-subject variation was small compared to the between-subject variation.

Adult↗
PubMed1993

A quality manual for the clinical laboratory including the elements of a quality system. Proposed guidelines.

Development of quality manuals is a means for the promotion of quality in clinical laboratories by describing the total quality system. It also provides opportunity of checking whether the quality system is implemented in reality and demonstrates to the hospital administration and the clinicians that the laboratory is committed to quality. The intention of these guidelines is to describe the elements of the quality system for a large clinical laboratory, and to present such a system in the form of a quality manual. The proposed guidelines comply, where relevant, with ISO/IEC guide 25 'General requirements for the technical competence of testing laboratories' and EN 45001 'General criteria for the operation of testing laboratories'. The document may be used as an aid for laboratories wishing to be accredited according to EN 45001, or intending to apply for formal certification of their quality systems, according to ISO 9001 'Quality systems--Model for quality assurance in design/development, production, installation, and servicing' utilizing ISO 9004 'Quality management and quality system elements--guidelines; Part 2 Guidelines for service'. However, information about the minimum requirements for official recognition should be obtained from the particular accreditation or certification body concerned.

Chemistry, Clinical↗
PubMed1990

Practical experience with a quality control procedure using retained patient specimens on Technicon H1 and COULTER S 880.

External quality assessment and internal quality control in hematology is complicated by the lack of good control materials. Commercial materials do not always behave as patient blood and they are expensive. Patient specimens are unstable, but may be used either within certain time limits or as in Bull's moving average for red cell indices. We have used retained patient specimens for internal quality control supplemented by a commercial control material. Three patient-specimens were run alternatively on a Technicon H1 and a Coulter 880 at regular intervals. The variations for each instrument and between instrument were computed. We used the 2 of 3 (2s) control rule. Our conclusion is that the Coulter 880 had an overall better performance than the Technicon H1 when using retained patient specimens. But both instruments practically met suggested analytical goals.

Goals↗