Daria Pašalić
Department of Medical Chemistry, Biochemistry and Clinical Chemistry
Zagreb University School of Medicine
Šalata ul 2.
10 000 Zagreb, Croatia
Phone +385 (1) 4590 205; +385 (1) 4566 940
E-mail: dariapasalic [at] gmail [dot] com

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Nazor A1, Juretić D2.ZR2-1: Fresh human blood as a control sample in EQA. Biochemia Medica 2009;19(Suppl 1):S89.
1Institute of Clinical Chemistry, Merkur University Hospital, Zagreb, Croatia
2Croatian Society of Medical Biochemists, Zagreb, Croatia
Corresponding author:aida [dot] nazor [at] gmail [dot] com
The aim is to ensure an objective, independent evaluation of haematological results and determine the degree of interlaboratory comparability on the national level which is the basis for harmonization of haematological results.
The fact that 37 various types of counters from different 11 manufacturers are used in more than 200 laboratories becomes the problem for defining the control sample. The area of laboratory haematology lacks the traceability according to the calibrator, which implies that an absolutely adequate control sample can not be produced for all of the analytical systems. To date, a commercial blood preparation has been used which was not applicable to all haematological counters, especially not in the process of differentiation of leucocytes (3-part and 5-part leukocytes differential) which was confirmed by the results in the external quality assessment in Croatia.
According to the recommendations made by EQALM (European Conference on Quality Assessment in Laboratory Medicine), the fresh human blood serves as the best control sample.
Following this recommendation and good experiences in conducting the assessment program in laboratory haematology in other countries a cooperation is established with Croatian Institute for Transfusion Medicine for preparation of control samples from fresh human blood.
The control samples, as a material made from humans, should be applicable to all of the haematological analytical systems and to all haematological exeminations done by the counters.
That would satisfy the aims of analytical quality for haematological counters, defined by the internationally accepted standards in which include all parameters of CBC and leukocytes differential.
Perkov S. ZR2-2: Comparison studies of pH, gas and ionised electrolytes in control and arterial mode. Biochemia Medica 2009;19(Suppl 1):S90.
Institute of Clinical Chemistry, Merkur University Hospital, Zagreb, Croatia
Corresponding author:sonja [dot] perkov [at] hdmb [dot] hr
In scope of the national program of external quality assessment pH, blood gases and ionized electrolytes are determined by 45 medical-biochemistry laboratories on different blood gas analyzers including RapidLab 248/348 2160/2165, Bayer diagnostics (N = 32), IL Gem Premier 3000, Instrumentation Laboratories (IL) (N = 6), Stats Profile pHOx Plus /Crital Care Xpress, Nova Biomedical (N = 2), AVL Opti 1/AVL 995, AVL Scientific Corporation (N = 2), Omni S, Roche diagnostics (N = 1), GASTAT 602i, Techno Medica Co., Ltd. (N = 1) and Ecosys II, Eschweiler GmbH & CoKG (N = 1).
Results of the cycle 3/2008 were processed for comparability evaluation of results of commercial control samples in control and arterial mode. Only 27 laboratories have submitted results in both modes. The results were processed regardless of the method and according to the methods for Bayer (N = 19) and IL analyzers (N = 4). Student‘s t-test was applied to estimate the result difference between control and arterial mode, with a significance level of P < 0.05.
Statistically significant differences were found in results for the partial pressure of carbon dioxide regardless of the method (P = 0.001) and according to the method for Bayer analyzers (P < 0.001), and in results for pH according to the method for Bayer analyzers (P = 0.022).
Considering different algorithms used in different types of blood gas analyzers to calculate pH, blood gases and ionized electrolytes in the commercial control solutions, whose composition differs significantly from human samples, we recommend that commercial control samples are analyzed according to the manufacturer’s instructions of blood gas analyzers.
Sikirica M1, Juretić D2.ZR2-3: Qualitative urine analysis – new approach. Biochemia Medica 2009;19(Suppl 1):S91.
1Institute of Clinical Chemistry, Merkur University Hospital, Zagreb, Croatia
2Croatian Society of Medical Biochemists, Zagreb, Croatia
Corresponding author:mirjana [dot] sikirica [at] gmail [dot] com
Qualitative urinalysis is a test mostly performed in a classical way what is due to its complexity time consuming and requires well educated staff, especially in morphological analysis of urine sediment elements. A new approach to the urinalysis presents its automatization by implementation of chemical analyzers for urine parameters estimation by test strips as well as automated microscopy. It enables total test standardization in every part of analytical process with significantly less time required for the whole procedure.
Results obtained from the national external quality assessment scheme (conducted by the Committee for External Quality Assessment of Croatian Society of Medical Biochemists, CSMB) from chemical analysis with test strip show that participating laboratories use a large number of test strips from different manufacturers. Visual measuring from test strips is still frequently in use, especially in primary health care laboratories (69%) while in secondary health care laboratories it is less frequent (44%). Results are commonly expressed in arbitrary units (1/+; 2/++; 3/+++; 4/++++). The European group for urinalysis recommends that results should be expressed semiquanititative within the International system of units (SI). Therefore, laboratories need to introduce instrumental measuring of results in order to make a test result more objective by implementation of standard procedure. Obtained results from identification of urine particle show that still a large number of medical biochemistry laboratories do not use sediment staining in light microscopy as the recommended procedure, whereas identification of cellular elements is expressed only on the basic level of microscopy differentiation. Cellular elements quantification is expressed differently. Similar to the chemical analysis of test strip, urine sediment microscopy is today also automated what makes cellular elements quantification more objective and furthermore enables to express the results in SI system.
Expanding the national external quality assurance scheme onto the postanalytical phase of issuing the test results as the final document of analytical process aims towards standardization of that part in order to achieve interlaboratory comparability which enables acceptance of test results regardless of where it has been performed.
Đurić K1, Juretić D2.ZR2-4:External Quality Assessment of hormone and tumor marker determination – our experience. Biochemia Medica 2009;19(Suppl 1):S92-S93.
1Medical Biochemistry Laboratory, Sunce Policlinic, Zagreb, Croatia
2Croatian Society of Medical Biochemists, Zagreb, Croatia
Corresponding author:koraljka [dot] duric [at] sunce [dot] hr
External Quality Assessment (EQA) in Medical Biochemistry Laboratories (MBL) in Croatia was organized two times per year for hormones (TSH, T3, T4, FT3, FT4) and tumor markers (CA15-3, CA-125, CA19-9, AFP, CEA, PSA) during 2008, and the same is planned for 2009 (only one cycle finished till now). Control samples used for EQA in surveys for hormones and tumor markers were commercial control materials with defined target values according to different analytical methods/instruments. Analytical goal setting for tumor marker was declared value of control sample ± 2SD and/or target value according to the combination of biological variation and clinical criteria. Analytical goal setting for hormone was declared value of control sample ± 2SD and/or target value according to the biological variation (total allowed analytical error).
A total of 56 laboratories participated for hormones and 50 laboratories for tumor markers during first survey in 2009. Among these, 19 (34%) in hormone module and 15 (30%) in tumor marker module were from primary health care facilities, respectively. Total number of participating laboratories in both modules was greater in 2009 survey when compared to two surveys in 2008 (on average 45 MLB participated for hormones and 42 for tumor markers).
Unfortunately, parallel with increase in total number of participating laboratories was increase in number of analytical methods/instruments different according to manufacturer. In the survey for tumor markers, most laboratories participated with PSA determination, and in the survey for hormones with TSH determination. The number of different analytical methods/instruments used for analyte determination increased from 8 to 10 for PSA and from 11 to 15 for TSH, when comparing surveys in 2008 to first one in 2009. Most laboratories participating in EQA surveys in Croatia during 2008 and 2009 used Roche Elecsys ECLIA methods for TSH, T3, T4, FT3, FT4 determination (39% on average) and CA15-3, CA-125, CA19-9, AFP, CEA, PSA (49% on average).
The application of defined quality specifications was possible only for 80% of laboratories in hormone survey and 90% in tumor marker survey, respectively. Calculations for other laboratories were not possible due to statistically inadequate number of results for some analytical methods/instruments (one or two results in every survey).
EQA results for hormones and tumor markers in 2008 and first half of 2009 showed unacceptable high overall variability (all analytical methods/instrument), expressed as coefficient of variation (KV), for TSH (13.9%), T3 (12.9%), FT4 (27.2%) and FT3 (27.4%). The average variability in three surveys for tumor markers was 8.1% for PSA, 11.2% for CA15-3, 11.3% for AFP, 11.5% for CEA, 13.6% for CA-125 and 26.9% for CA19-9.
Due to significant heterogeneity of immunochemical analytical methods and instruments participating in EQA surveys for hormones and tumor markers (and statistically inadequate number of results for most of them as a consequence), the results of these surveys were not taken into account for overall scoring of laboratory achievement of analytical quality goals.
Vučić Lovrenčić M1, Božičević S1, Juretić D2.ZR2-5:External Quality Assessment for hemoglobin A1c (2005-2009). Biochemia Medica 2009;19(Suppl 1):S93-S94.
1Vuk Vrhovac University Clinic for Diabetes, Endocrinology and Metabolic Diseases, Zagreb, Croatia
2Croatian Society of Medical Biochemists, Zagreb, Croatia
Corresponding author:vucic [at] idb [dot] hr
External quality assessment (EQA) for hemoglobin A1c determination was implemented in Croatia in 2005.
Regarding well-known controversies within an unfinished global hemoglobin A1c harmonization project, we aimed this EQA module within the Croatian Society of Medical Biochemists EQAS as a tool to obtain as high degree of result harmonization as possible, by using inter-laboratory comparisons of analytical quality.
Commercially available liophylizates with declared target values according to both IFCC and NGSP reference systems for a large number of methods/reagents were selected as control materials.
28 laboratories participated in the first EQA-cycle at the end of 2005. 3, 2, 2 and 1 cycle(s) were conducted in 2006, 2007, 2008 and 2009 (sofar), respectively.
Average number of participants/cycle showed a continuous increase (29, 34, 36 and 44 in 2006, 2007, 2008 and 2009, respectively).
Immunoturbidimetric methods are the most common (96%), whereas an almost negligible proportion of column-chromatograpy (4%) was reported.
A continuous improvement in quality has been observed by using criteria defined in the ERL (European Reference Laboratory for Glycohemoglobin) Programme. A proportion of the laboratories reporting results with bad/unacceptable deviations fom target values decreased from 25% at the beginning to 22%, 15%, 11% and 7% in the 2006, 2007, 2008 and first cycle in 2009, respectively.
These results confirm the validity of implementation of EQA for hemoglobin A1c and support further activities aimed to improve quality, as well as clinical availability and utilization of hemoglobin A1c as a key laboratory parameter for the glycemic control evaluation in diabetic patients.
Flegar-Meštrić Z1, Juretić D2.ZR2-6:Review on quality requirements in Croatian EQA schemes. Biochemia Medica 2009;19(Suppl 1):S94-S95.
1Institute of Clinical Chemistry, Merkur University Hospital, Zagreb, Croatia
2Croatian Society of Medical Biochemists, Zagreb, Croatia
Corresponding author:zlata [dot] mestric [at] zg [dot] t-com [dot] hr
Organizer of interlaboratory comparison program is responsible for design of the scheme, for help provided to laboratories in analysis of unacceptable results, for reporting about obtained results that must include: target value interpretation, result evaluation method, plot of obtained results and continuous monitoring of result from each individual participating laboratory. Nowadays, the EQA organizers encounter numerous challenges related to new national law regulations and analytical quality requirements regarding global harmonization of clinical chemistry, accreditation procedures and introducing the European directive for in vitro diagnosis „European Directive 98/79/EC“. This directive also includes requirements for expressing traceability of calibrator and control material by available reference measuring procedures and/or reference materials of higher order.
According to the new accepted standard for organizers of interlaboratory comparisons ISO/IEC 17043 – Conformity Assessment-General requirements for PT, the organizer needs, whenever possible, to assure control materials with known target values (assigned values) and known traceability to the higher order reference materials. Only in case of non-standard methods, like in many coagulation tests such control materials are not available, so in that case we can take mean group results as target values according to applied analytical methods or systems (consensus values).
In national external quality assessment scheme for medical biochemical laboratories in Croatia target values of laboratory test results are defined as mean target values of the group ± 2SD according to different methods (consensus value). The goal of the Committee for External Quality Assessment of Croatian Society of Medical Biochemists (CSMB) is to harmonize as much as possible the way of result assessment with internationally accepted criteria, what means, to enable application of such control samples with known traceability to higher order reference materials and expressed target value with appropriate measuring uncertainty.
For acceptability evaluation of participating laboratories’ test results we shall continue to implement internationally accepted hierarchical approach to analytical quality goals which include metrological principles, biological variation, diagnostic needs and clinical usefulness.
The task of medical biochemical laboratories in described system is to provide test results that are reliable and comparable on the international level. Therefore, it is essential to conduct continuous educational activities and put the metrological consciousness on a higher level, what the program of interlaboratory comparisons can contribute to.
Juretić D.ZR2-7:Postanalytical phase as a modul in the national External Quality Assessment scheme for medical-biochemistry laboratories. Biochemia Medica 2009;19(Suppl 1):S95-S96.
Croatian Society of Medical Biochemists, Zagreb, Croatia
Corresponding author:dubravka [dot] juretic09 [at] gmail [dot] com
Sources of interlaboratory variability could be recognized by application of appropriate programs for the evaluation of external quality assessment (EQA) data which include results of medical biochemistry laboratories as well as details on analytical methods and analytical systems used. Therefore, it is important that EQA schemes exist on the national level and that their organization could be improved continuously according to the international recommendations. Furthermore, EQA programs could provide the basis for the introduction and continuously monitoring of modern technology and new recommendations in all phases of the laboratory work.
In Croatia, a great impact on the increase of interlaboratory comparison has been done by the project on harmonization of laboratory results organized in collaboration of the Croatian Chamber of Medical Biochemists, Institute of Clinical Chemistry Clinical Hospital Merkur as a reference center of the Ministry of Health for the determination of the reference intervals in the field of general medical biochemistry and the Croatian Society of Medical Biochemists as the organizer of the EQA schemes for medical biochemistry laboratories. The goal of the project was to improve analytical and clinical comparability of the results between the medical biochemistry laboratories on primary, secondary and tertiary levels. According to the evaluation of the EQA results in the period from 1998 to 2003, it was obvious that some of the previously recommended analytical methods have to be revised to enable clinical comparison of the laboratory results through application of common reference intervals.
Due to the implementation of the mentioned harmonization program in the field of laboratory methods and common reference intervals, prerequisites are achieved for the introduction of extra-analytical phases in the national EQA program.
Goal of the post-analytical phase as a module in the national EQA scheme is to analyze the laboratory reports as a final documents prepared by 212 medical biochemistry laboratories in Croatia according to the recommendations shortly presented in the document on harmonization of laboratory reports in the field of general, special and very sophisticated medical biochemistry analysis, issued by the Croatian Chamber of Medical Biochemists 2007.
Harmonization in the field of laboratory results reporting – post-analytical phase as a final document of the analytical process is based on IFCC and IUPAC recommendations (A Proposal for an IUPAC-IFCC Recommendation. Syntax and Semantic Rules for Quantities and Units in Clinical Laboratory Sciences 1993: stage 1, draft 4.) and on the requirements for the accreditation of medical laboratories (HRN EN ISO 15189:2006.).
Due to the fact that comparability of the laboratory analyses depends on the standardization of all phases of the laboratory work, EQA programs for medical biochemistry laboratories have to include also pre-analytical phase as a source of the significant number of laboratory errors. Then it will be possible to gain the complete insight in the state of the art of the medical biochemistry profession with the goal to permanently improve the quality of medical biochemistry laboratories on the national as well as international level.